830 Federal Register / Vol. 89, No. 4 / Friday, January 5, 2024 / Proposed Rules 

1This document discusses both drunk driving 

and alcohol-impaired driving. Drunk driving, as 

used in this document, is understood to be 

operating a vehicle at or above the threshold of 

alcohol concentration in the blood established by 

law. Alcohol-impaired driving describes the entire 

set of impairments of various driving-related skills 

and can occur at lower concentrations of alcohol. 

DEPARTMENT OF TRANSPORTATION 

National Highway Traffic Safety 

Administration 

49 CFR Part 571 

[Docket No. NHTSA–2022–0079] 

RIN 2127–AM50 

Advanced Impaired Driving Prevention 

Technology 

AGENCY: National Highway Traffic 

Safety Administration (NHTSA), 

Department of Transportation. 

ACTION: Advance notice of proposed 

rulemaking. 

SUMMARY: This document initiates 

rulemaking that would gather the 

information necessary to develop 

performance requirements and require 

that new passenger motor vehicles be 

equipped with advanced drunk and 

impaired driving prevention technology 

through a new Federal Motor Vehicle 

Safety Standard (FMVSS). In this 

document, NHTSA presents its various 

activities related to preventing drunk 

and impaired driving and discusses the 

current state of advanced impaired 

driving technology. NHTSA also asks 

many questions to gather the 

information necessary to develop a 

notice of proposed rulemaking on 

advanced drunk and impaired driving 

technology. 

DATES: Comments should be submitted 

no later than March 5, 2024. 

ADDRESSES: You may submit comments 

to the docket number identified in the 

heading of this document by any of the 

following methods: 

• Federal eRulemaking Portal: Go to 

https://www.regulations.gov. Follow the 

online instructions for submitting 

comments. 

• Mail: Docket Management Facility: 

U.S. Department of Transportation, 1200 

New Jersey Avenue SE, West Building 

Ground Floor, Room W12–140, 

Washington, DC 20590–0001. 

• Hand Delivery or Courier: 1200 

New Jersey Avenue SE, West Building 

Ground Floor, Room W12–140, between 

9 a.m. and 5 p.m. ET, Monday through 

Friday, except Federal holidays. 

• Fax: 202–493–2251. 

Instructions: All submissions must 

include the agency name and docket 

number. Note that all comments 

received will be posted without change 

to http://www.regulations.gov, including 

any personal information provided. 

Please see the Privacy Act discussion 

below. NHTSA will consider all 

comments received before the close of 

business on the comment closing date 

indicated above. To the extent possible, 

the agency will also consider comments 

filed after the closing date. 

Docket: For access to the docket to 

read background documents or 

comments received, go to https://

www.regulations.gov at any time or to 

1200 New Jersey Avenue SE, West 

Building Ground Floor, Room W12–140, 

Washington, DC 20590, between 9 a.m. 

and 5 p.m., Monday through Friday, 

except Federal Holidays. Telephone: 

202–366–9826. Confidential Business 

Information: If you wish to submit any 

information under a claim of 

confidentiality, submit these materials 

to NHTSA’s Office of the Chief Counsel 

in accordance with 49 CFR part 512. All 

requests for confidential treatment must 

be submitted directly to the Office of the 

Chief Counsel. NHTSA is currently 

treating electronic submission as an 

acceptable method for submitting 

confidential business information to the 

agency under part 512. If you claim that 

any of the information or documents 

provided in your response constitutes 

confidential business information 

within the meaning of 5 U.S.C. 

552(b)(4), or are protected from 

disclosure pursuant to 18 U.S.C. 1905, 

you may submit your request via email 

to Dan Rabinovitz in the Office of the 

Chief Counsel at Daniel.Rabinovitz@

dot.gov. Do not send a hardcopy of a 

request for confidential treatment to 

NHTSA’s headquarters. 

FOR FURTHER INFORMATION CONTACT: Ms. 

Chontyce Pointer, Office of Crash 

Avoidance Standards, Telephone: 202– 

366–2987, Ms. Sara R. Bennett, 

Telephone: 202–366–7304 or Mr. Eli 

Wachtel, Telephone: 202–366–3065, 

Office of Chief Counsel. Address: 

National Highway Traffic Safety 

Administration, 1200 New Jersey 

Avenue SE, Washington, DC 20590. 

SUPPLEMENTARY INFORMATION: 

Table of Contents 

I. Executive Summary 

II. Introduction 

A. Background Information About 

Impaired Driving States 

B. Many Different Behavioral Strategies 

Exist, Yet Impaired Driving Persists 

C. NHTSA’s Authority 

III. Advanced Drunk and Impaired Driving 

Prevention Safety Problem 

A. Drunk Driving 

B. Distracted Driving 

C. Drowsy Driving 

IV. Overview of Current Efforts To Address 

Drunk and Impaired Driving 

A. State and Federal Behavioral Prevention 

Activities 

1. Deterrence 

2. Prevention 

3. Communications Campaigns 

4. Alcohol and Drug Treatment, 

Monitoring, and Control 

B. Vehicle-Based Countermeasures 

1. Summary of Research on Vehicle-Based 

Countermeasures 

2. Passive Detection Methods and 

Available Technologies 

3. Proposed Vehicle Interventions Once 

Driver Impairment or BAC Is Detected 

V. Summary of Other Efforts Related to 

Impaired Driving 

VI. Privacy and Security 

VII. Consumer Acceptance 

VIII. General Questions for the Public 

IX. Rulemaking Analyses and Notices 

A. Executive Order 12866, Executive Order 

13563, Executive Order 14094, and DOT 

Regulatory Policies and Procedures 

B. Privacy Act 

C. Regulation Identifier Number (RIN) 

I. Executive Summary 

Alcohol-impaired driving 1 is a major 

cause of crashes and fatalities on 

America’s roadways. The National 

Highway Traffic Safety Administration 

(NHTSA) has been actively involved in 

addressing alcohol-impaired driving 

since the 1970s. Recent developments in 

vehicle technology present new 

opportunities to further reduce drunk 

and impaired driving crashes and 

fatalities or eliminate them altogether. 

Private and public researchers have also 

made significant progress on 

technologies that are capable of 

measuring and quantifying driver state 

and performance (e.g., hands on the 

steering wheel, visual gaze direction, 

lane position). However, harnessing 

these technologies for drunk and 

impaired driving detection and 

prevention remains a significant 

challenge. NHTSA’s information 

gathering and research efforts have 

found that several technologies show 

promise for detecting various states of 

impairment, which for the purposes of 

this document are alcohol, drowsiness, 

and distraction. However, technological 

challenges, such as distinguishing 

between different impairment states, 

avoiding false positives, and 

determining appropriate prevention 

countermeasures, remain. Due to 

technology immaturity and a lack of 

testing protocols, drugged driving is not 

being considered in this advance notice 

of proposed rulemaking. 

The Infrastructure Investment and 

Jobs Act (Bipartisan Infrastructure Law 

or BIL) directs NHTSA to issue a final 

rule establishing a Federal Motor 

Vehicle Safety Standard (FMVSS) that 

requires new passenger vehicles to have 


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Federal Register / Vol. 89, No. 4 / Friday, January 5, 2024 / Proposed Rules 831 

2 Infrastructure Investment and Jobs Act, Public 

Law 117–58, 135 Stat. 429 section 24220 (2021). 

3For the purposes of this document, NHTSA uses 

the term ‘‘passive’’ to mean that the system 

functions without direct action from vehicle 

occupants. Further information about the use of the 

term ‘‘passive’’ is available in the ‘‘NHTSA’s 

Authority’’ section. 

4Part 392 of the Federal Motor Carrier Safety 

Regulations prohibits any driver from operating a 

commercial motor vehicle (CMV) while the driver’s 

ability or alertness is so impaired, or so likely to 

become impaired, through fatigue, illness, or any 

other cause, as to make it unsafe for him/her to 

continue to operate the CMV. In addition, part 392 

prohibits drivers from operating a CMV while (1) 

under the influence of, or using, specified drugs 

and other substances, and (2) under the influence 

of, or using, alcohol within specified time and 

concentration limits. Further, part 392 prohibits 

drivers from texting or using a hand-held mobile 

telephone while driving a CMV. 

5 Drugged driving is excluded from the scope and 

is discussed more in the Introduction, A. 

‘‘Background information about impaired driving 

states’’ of this document. 

6NHTSA has stated that distracted driving 

includes talking on mobile phones, texting, eating, 

and other non-driving activities. 

7Comprehensive economic costs account for the 

total societal harm associated with fatalities and 

injuries, including economic impacts and 

valuations of lost quality-of-life. See Blincoe, L., 

Miller, T., Wang, J.-S., Swedler, D., Coughlin, T., 

Lawrence, B., Guo, F., Klauer, S., & Dingus, T. 

(2023, February). The economic and societal impact 

of motor vehicle crashes, 2019 (Revised) (Report 

No. DOT HS 813 403). National Highway Traffic 

Safety Administration. 

8Fatalities ‘‘involving reported distraction’’ refers 

to fatalities where a law enforcement officer 

reported a driver in a fatal crash as having been 

distracted at the time of the crash, which is 

associated with underreporting of all crashes, 

fatalities, and injuries involving and caused by 

distraction. 

9The previous DADSS technology requires a 

directed breath toward a sensor to measure breath 

alcohol concentration (BrAC). The DADSS research 

and development effort is continuing to focus on 

developing technology that does not require a 

directed breath to detect the presence of alcohol. 

‘‘advanced drunk and impaired driving 

prevention technology’’ by 2024.2 The 

BIL also provides that an FMVSS should 

be issued only if it meets the 

requirements of the National Traffic and 

Motor Vehicle Safety Act. (‘‘Safety 

Act’’). BIL defines the relevant 

technology as technology that can 

passively 3 and accurately monitor 

driver performance to detect 

impairment or passively and accurately 

measure driver blood alcohol 

concentration (BAC) (or both in 

combination) and prevent or limit 

vehicle operation if impairment is 

detected. Given the current state of 

driver impairment detection technology, 

NHTSA is issuing this advance notice of 

proposed rulemaking (ANPRM) to 

inform a possible future FMVSS that 

can meet the requirements of the 

Vehicle Safety Act. 

This ANPRM presents a summary of 

NHTSA’s knowledge of alcohol’s impact 

on driver performance and seeks 

comment on a variety of issues related 

to the state of development of driver 

impairment detection technologies. It 

also sets forth the research and 

technological advancements necessary 

to develop a FMVSS for driver 

impairment. This document also 

presents three regulatory options for 

how the agency might mitigate driver 

impairment: blood alcohol content 

detection, impairment-detection (driver 

monitoring), or a combination of the 

two. 

II. Introduction 

Driver impairment, as used in 

reference to motor vehicle safety, is a 

broad term that could encompass many 

different driver states that present 

operational safety risks.4 There is no 

clear and consistent engineering or 

industry definition of ‘‘impairment.’’ 

‘‘Impaired’’ can mean anything that 

diminishes a person’s ability to perform 

driving tasks and increases the 

likelihood of a crash. Considering this, 

driver impairment would include drunk 

and drugged driving,5 but it could also 

include drowsy driving, distracted 

driving,6 driving while experiencing an 

incapacitating medical emergency or 

condition, or any other factor that 

would diminish driver performance and 

increase potential crash risk. All these 

driver states present operational safety 

risks, and each presents differing 

problem sizes and degrees of risk, 

underlying causes, states of research, 

data demonstrating risks from that 

driver state, and potential vehicle 

technological countermeasures that 

could resolve or mitigate resulting 

operational safety risks. Additionally, 

not all states of driver impairment are 

immediately redressable, meaning that 

while a vehicle safety system might help 

a distracted or drowsy person pay 

attention again, it may not help a driver 

be less alcohol- or drug-impaired. This 

difference among the driver impairment 

states is particularly important when 

considering what type of standard or 

countermeasure would be the most 

appropriate. 

The negative economic and societal 

impacts related to impaired driving are 

enormous and devastating in the United 

States. Recent NHTSA research has 

identified the scope of causal factors 

associated with fatal and non-fatal 

injuries in crashes, revealing key 

differences among outcomes associated 

with reported contributory factors 

versus estimated causal factors.7

NHTSA estimates here that in 2021: 

approximately 12,600 traffic fatalities 

were ‘‘caused by alcohol impairment,’’ 

versus approximately 13,400 fatalities 

‘‘involving alcohol;’’ 12,400 fatalities 

were ‘‘due to distraction’’ 8, but and 

drowsy driving led to at least 684 

fatalities. Differences in values 

associated with reported contributory 

factors versus causal factors are driven 

by offsetting forces; underreporting is a 

predominant issue for estimates of 

fatalities and injuries caused by 

distraction and possibly drowsy driving, 

while at least some fatalities and nonfatal injuries associated with alcohol 

and distraction likely had other causal 

factors. The enormous safety potential 

of addressing the three states of 

impaired driving considered here 

impels NHTSA’s activities relating to 

driver impairment. 

With respect to alcohol impairment, 

NHTSA has been conducting behavioral 

research and implementing behavioral 

safety strategies and programs, public 

education, and enforcement campaigns 

to combat drunk driving. Despite these 

efforts, which have contributed to 

significant declines in fatalities over the 

past several decades, drunk driving 

remains a significant safety risk for the 

public. NHTSA is also engaged in 

technology-based research. This 

includes better understanding of the 

technological capabilities that measure 

drivers’ eye movements and vehicle 

inputs. In addition, through the Driver 

Alcohol Detection System for Safety 

(DADSS) program, NHTSA is actively 

involved in cutting-edge research to 

help develop technology to quickly, 

accurately, and passively 9 detect a 

driver’s BAC. Upon completion of this 

development work, this technology may 

prevent drivers from shifting their 

vehicles into gear if they attempt to 

operate the vehicle at a BAC above the 

legal limit. NHTSA believes that the 

passive DADSS technology, still in 

development, may be one way to meet 

the BIL mandate, and that prevention of 

drunk driving is the best way to reduce 

the number of crashes and resulting 

fatalities and injuries that occur due to 

alcohol-impaired driving. 

Concerted efforts by NHTSA, States, 

and other partners to implement proven 

strategies generated significant 

reductions in alcohol-impaired driving 

fatalities since the 1970s when NHTSA 

records began; but progress has stalled. 

Between 2011 and 2020, an average of 

almost 10,500 people died each year in 

alcohol-impaired driving crashes. The 

agency has seen record increases in 

overall traffic fatalities over the last few 

years of the COVID–19 pandemic, likely 

reflecting increases in alcohol- and 


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832 Federal Register / Vol. 89, No. 4 / Friday, January 5, 2024 / Proposed Rules 

10Office of Behavioral Safety Research (2021, 

October). Continuation of research on traffic safety 

during the COVID–19 public health emergency: 

January–June 2021. (Report No. DOT HS 813 210). 

National Traffic Safety Administration. 11Available at https://www.transportation.gov/ 

NRSS. 

12https://safety.fhwa.dot.gov/zerodeaths/docs/ 

FHWA_SafeSystem_Brochure_V9_508_200717.pdf. 

13United States Department of Transportation 

(2022, October). What is a safe system. Website: 

https://www.transportation.gov/NRSS/SafeSystem. 

14 It also observes that considerable progress in 

behavioral research has been made to advance the 

knowledge and understanding of the physiological 

effects of both alcohol- and drug-impaired driving. 

15 Id. at 16. 

16Taylor, C.L., Byrne, A., Coppinger, K., Fisher, 

D., Foreman, C., & Mahavier, K. (2022, June). 

Synthesis of studies that relate amount of 

enforcement to magnitude of safety outcomes 

(Report No. DOT HS 813 274–A). National Highway 

Traffic Safety Administration. 

17Meaning that metrics, such as BAC, currently 

exist to measure the type of impairment. 

drug-impaired driving.10 While the 

causes of the recent fatality increases 

require further study and NHTSA 

continues to support strategies to 

change driver behavior, more must be 

done to reach our goal of zero traffic 

fatalities. Accordingly, in January 2022, 

DOT issued its National Roadway Safety 

Strategy (NRSS) to address the crisis of 

deaths on the nation’s roadways.11 The 

NRSS adopts the Safe Systems 

Approach 12 as the guiding paradigm to 

address roadway safety and focuses on 

five key objectives: safer people, safer 

roads, safer vehicles, safer speeds, and 

improved post-crash care. The Safe 

System Approach works by building 

and reinforcing multiple layers of 

protection both to prevent crashes from 

happening in the first place and to 

minimize the harm to those involved 

when crashes do occur.13 Drunk and 

impaired driving is an NRSS priority.14

The NRSS’s Safe System Approach 

involves using all available tools, 

including education, outreach, 

enforcement, and engineering solutions, 

including motor vehicle technologies 

like alcohol, drowsiness, and visual 

distraction detection systems.15 Vehicle 

technologies that can help prevent and 

mitigate risky behaviors and driver 

impairment are a key element of the 

safer vehicles element of this approach. 

To complement behavioral campaigns, 

which have reduced, but not eliminated, 

driving while impaired,16 NHTSA is 

considering what technological 

countermeasures and performance 

requirements could be applied to motor 

vehicles that would achieve the NRSS 

safety objectives. Graph 1 provides an 

overview of the alcohol-impaired 

fatalities since the early 1980s. 

Addressing each impaired driving 

state has its own set of unique 

challenges. For some, such as alcohol, 

technological solutions are not yet 

readily available that would 

consistently prevent a significant 

proportion of crashes caused by that 

impaired driving state. For others, such 

as distraction and drowsiness, there is 

evidence that police-reported crash data 

likely underestimate their role in crash 

causation. Amidst this uncertainty, the 

agency has many questions that must be 

answered to develop a proposal that 

will meet all statutory requirements and 

Departmental priorities. 

Given the breadth of impairment 

states, severities, detection technologies, 

and interventions, it is valuable to take 

this opportunity to clarify the scope of 

this effort. In view of the larger number 

of fatalities associated with alcohol 

impairment and the well-defined legal 

thresholds and measurements available 

for alcohol impairment, as compared 

with other types of impairment, NHTSA 

is focusing this ANPRM on alcohol 

impairment.17 However, based on the 

language in BIL, NHTSA believes that 

Congress did not intend to limit 

NHTSA’s efforts under BIL to alcohol 

impairment. Therefore, while alcohol 

impairment is the focus, this ANPRM 

also covers two additional impairment 

states: drowsy driving and distracted 

driving. NHTSA chose these states for 

two reasons. First, the size of the safety 

problem—in particular that of distracted 

driving—is immense. Second, certain 

sensor technologies that have the 

potential to detect or assist in detecting 

alcohol impairment and are or can be 

incorporated into driver monitoring 

systems (DMS) may also have the 

potential to detect drowsy and 

distracted driving. Including these 

impairment states in this effort therefore 

presents an opportunity to deliver 

significant additional safety benefits to 

the American people. These 

technological considerations are 

discussed in greater detail in Section IV. 

B. ‘‘Vehicle Based Countermeasures’’. 

Additionally, it is important to 

understand the many challenges with 

trying to identify and prevent the 

different types of impaired driving with 

a single performance standard. The 

agency is interested in learning more 

from commenters about what 

technologies and associated metrics 

might identify multiple types of 


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Graph 1. Alcohol-Impaired Fatality Trend 

-Total Number of Alcohol-Impaired Fatalities -Percentage of Tota! F ata!ities that were Alcohol-impaired 

25.000 60% 
Federal Register / Vol. 89, No. 4 / Friday, January 5, 2024 / Proposed Rules 833 

18The realization of additional safety benefits 

may depend on the performance requirements 

chosen by NHTSA, or the technological solution 

deployed by manufacturers. 

19The term alcohol in this report refers to ethyl 

alcohol, or ethanol, which is the principal 

ingredient in alcoholic drinks and the substance 

measured to determine blood alcohol concentration. 

20Moskowitz, H., & Burns, M. (1990). Effects of 

alcohol on driving performance. Alcohol Health & 

Research World, 14(1), 12–15. 

21Paton, A. (2005). Alcohol in the body. BMJ, 

330(7482), 85–87. 

22National Highway Traffic Safety 

Administration. (2016). The ABCs of BAC: A guide 

to understanding blood alcohol concentration and 

alcohol impairment. Retrieved from https://

www.nhtsa.gov/document/theabcsofbac. 

23Zakhari, S. (2006). Overview: how is alcohol 

metabolized by the body? Alcohol research & 

health, 29(4), 245. 

24 23 U.S.C. 163. 

25https://www.nhtsa.gov/risky-driving/drunkdriving#the-issue-alcohol-effects. 

26https://www.nhtsa.gov/risky-driving/drunkdriving#:∼:text=Alcohol%20is%20a%20substance

%20that,the%20central%20nervous%20

system%20increase. 

impaired drivers.18 Also, as discussed in 

later sections, one of the options the 

agency is considering presents 

challenges with accurately 

differentiating alcohol impairment from 

other types of impairment, like 

drowsiness, assuming differentiation is 

desired and necessary to select 

appropriate alerts, warnings, or 

interventions. In later sections, we 

discuss different types of impairment 

that might be identified by a particular 

technology. 

It is also important to be clear here 

that driving while impaired with drugs 

other than alcohol (drugged driving) is 

not within the scope of this ANPRM 

even though drug impairment is also a 

significant problem. Many different 

drugs can affect drivers, and current 

knowledge about the effects of each on 

driving performance is limited. 

Furthermore, the technology and testing 

protocols for drugs other than alcohol, 

in the driving context, are not mature 

enough to indicate the degree of 

impairment and the risk of crash 

involvement that results from the use of 

individual drugs. Therefore, drugged 

driving is beyond the scope of this 

rulemaking effort but remains important 

to the Department and agency as it 

addresses fatal and serious crashes. The 

complexities inherent in the drugged 

driving safety problem are discussed in 

more detail in the following section. 

A. Background Information About 

Impaired Driving States 

Drunk Driving 

Alcohol 19 impairment can lead to 

altered and negative behaviors, as well 

as physical conditions that increase the 

risk of unintentional injuries, 

particularly when driving. Alcohol is 

known to impair various drivingrelevant abilities such as perception, 

visuomotor coordination, psychomotor 

performance, information processing 

and decision making, and attention 

management.20 When consumed, 

alcohol is absorbed from the stomach 

and distributed by the blood stream 

throughout the body.21 BAC is measured 

as the weight of alcohol in a certain 

volume of blood and expressed in grams 

per deciliter (g/dL).22 The rise and fall 

of alcohol in the bloodstream (and thus, 

the BAC) depends on the interplay 

between various factors that determine 

the metabolization of alcohol within the 

person’s body including frequency and 

amount of alcohol consumed, age, 

gender, body mass, consumption of 

other food, genetic factors, and time 

since alcohol consumption.23

In the United States, in general, a BAC 

of .08 g/dL and higher in drivers is 

defined as legally impaired 24 and a 

condition for arrest (in Utah, a BAC at 

or above .05 g/dL is the illegal limit). 

However, alcohol-impairment of various 

driving-related skills can occur at lower 

concentrations, and alcohol-impaired 

drivers can pose serious injury risks to 

themselves and others with any amount 

of alcohol in their bodies. As alcohol 

BAC levels rise in a person’s system, the 

negative effects on the central nervous 

system increase.25 Alcohol affects the 

body in a way that negatively impacts 

the skills needed for a person to drive 

safely because it impairs the function of 

the brain that relates to thinking, 

reasoning, and muscle coordination.26

Table 1 provides an overview of the 

typical and predictable effects on 

driving over a range of BAC levels. 

TABLE 1—EFFECTS OF ALCOHOL ON DRIVING 27 28

Blood alcohol concentration 

(g/dL) Typical effects Predictable effects on driving 

.02 ........................................ • Some loss of judgment ................................................

• Relaxation ....................................................................

• Slight body warmth ......................................................

• Altered mood ...............................................................

• Decline in visual functions (rapid tracking of a moving 

target). 

• Decline in ability to perform two tasks at the same 

time (divided attention). 

.05 ........................................ • Exaggerated behavior .................................................

• May have loss of small-muscle control (e.g., focusing 

your eyes).

• Impaired judgment .......................................................

• Euphoric feeling ...........................................................

• Lowered alertness .......................................................

• Release of inhibition ....................................................

• Reduced coordination. 

• Reduced ability to track moving objects. 

• Difficulty steering. 

• Reduced response to emergency driving situations. 

.08 ........................................ • Muscle coordination becomes poor (e.g., balance, 

speech, vision, reaction time, and hearing).

• Harder to detect danger ..............................................

• Impaired judgment, self-control, reasoning, and memory.

• Reduced concentration. 

• Short-term memory loss. 

• Reduced and erratic speed control. 

• Reduced information processing capability (e.g., signal detection, visual search). 

• Impaired perception. 

.10 ........................................ • Clear deterioration of reaction time and control .......... • Reduced ability to maintain lane position and brake 

appropriately. 

• Slurred speech, poor coordination, and slowed thinking.

.15 ........................................ • Far less muscle control than normal ...........................

• Vomiting may occur (unless this level is reached 

slowly or a person has developed a high tolerance 

for alcohol).

• Substantial impairment in vehicle control, attention to 

driving task, and in necessary visual and auditory information processing. 


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834 Federal Register / Vol. 89, No. 4 / Friday, January 5, 2024 / Proposed Rules 

27Table 1 should be used as a reference point for 

population-level analysis. The outlined effects may 

apply to certain individuals, but for the reasons 

discussed above, may vary from individual to 

individual. It should also be noted that while some 

effects are listed at multiple BACs (e.g., difficulty 

steering), the effects are more likely to occur and 

more severe at higher BACs. Information in this 

table shows the BAC level at which the effect 

usually is first observed. 

28Adapted from National Highway Traffic Safety 

Administration. (2016). The ABCs of BAC: A guide 

to understanding blood alcohol concentration and 

alcohol impairment. Retrieved from https://

www.nhtsa.gov/document/theabcsofbac. 

29Fillmore, M.T., & Vogel-Sprott, M.J.A.C. (1998). 

Behavioral impairment under alcohol: cognitive 

and pharmacokinetic factors. Alcoholism: Clinical 

and experimental research, 22(7), 1476–1482. 

30Nicholson, M.E., Wang, M., Airhihenbuwa, 

C.O., Mahoney, B.S., Christina, R., & Maney, D.W. 

(1992a). Variability in behavioral impairment 

involved in the rising and falling BAC curve. 

Journal of Studies on Alcohol, 53(4), 349–356. 

31Burian, S.E., Hensberry, R., & Liguori, A. 

(2003). Differential effects of alcohol and alcohol 

expectancy on risk-taking during simulated driving. 

Human Psychopharmacology: Clinical and 

Experimental, 18(3), 175–184. 

32 Vogel-Sprott, M. (1997). Is behavioral tolerance 

learned? Alcohol health and research world, 21(2), 

161. 

33 Id. 

34https://crashstats.nhtsa.dot.gov/Api/Public/ 

ViewPublication/813120. 

35Berning, A., Smith, R. Drexler, M., Wochinger, 

K. (2022). Drug Testing and Traffic Safety: What 

You Need to Know. United States. Department of 

Transportation. (Report No. DOT HS 813 264). 

Washington, DC. National Highway Traffic Safety 

Administration. 

36 ‘‘Drug positive’’ indicates that a driver has 

tested positive for a drug (or drugs). However, 

testing positive for a drug does not indicate 

impairment nor any degree of potential impairment. 

37Berning, et al., 2022. 

38Compton, R., Vegega, M. Smither, D. (2009). 

Drug Impaired Driving: Understanding the Problem 

and Ways to Reduce It. DOT HS 811 268. 

Washington, DC. NHTSA. 

39Harris, D.H., Dick, R.A., Casey, A.M., and 

Jarosz, C.J. (1980) The Visual Detection of Driving 

While Intoxicated: Field Test of Visual Cues and 

Detection Methods. DOT–HS–905–620. 

Washington, DC: NHTSA. 

40Stuster, J.W. (1997). The Detection of DWI at 

BACs Below 0.10. (Report No. DOT HS 808 654). 

Washington, DC: U.S. Department of 

Transportation, NHTSA. 

TABLE 1—EFFECTS OF ALCOHOL ON DRIVING 27 28—Continued 

Blood alcohol concentration 

(g/dL) Typical effects Predictable effects on driving 

• Significant loss of balance.

The driving skill decrements in Table 

1 provide a means of approximating the 

impairment correlated with BAC levels. 

However, BAC is a measure of the 

amount of alcohol in the bloodstream 

rather than a reliable indicator of the 

degree of impairment.29 30 At least two 

factors contribute to the lack of a precise 

one-to-one correlation between BAC and 

impairment. First, regular drinkers may 

learn strategies for more cautious 

driving to compensate for their 

perceived skill decrements.31 32 Second, 

there is also empirical evidence that 

some regular drinkers develop a higher 

tolerance to alcohol, which results in 

less apparent declines in cognitive and 

motor performance after consuming low 

to moderate doses.33 Therefore, BAC 

levels provide an imperfect 

measurement of probable impairment. 

Nearly two thirds of all alcoholimpaired fatalities involve high blood 

alcohol levels with a BAC level at or 

greater than 0.15 g/dL.34 Yet even a 

small amount of alcohol can affect an 

individual’s driving ability. In 2020, 

there were 2,041 people killed in 

alcohol-related crashes where a driver 

had a BAC level of .01 to .07 g/dL. 

State alcohol impairment laws and 

alcohol detection devices focus on 

measuring the alcohol concentration in 

BAC and breath alcohol concentration 

(BrAC). These are the two 

measurements that State laws and 

alcohol detection devices utilize to 

determine whether someone is 

considered driving over the legal limit 

(i.e., whether the person can be 

considered driving drunk, with ‘‘drunk’’ 

being defined as above the threshold of 

alcohol concentration established by 

law). BrAC is measured with a breath 

test device that measures the amount of 

alcohol in a driver’s breath. BAC is 

usually measured via a blood test. 

Technology is under development that 

would allow for measurement in new 

ways. For example, one technology uses 

touch- or tissue-based detection of light 

absorption at pre-selected wavelengths 

from a beam of light reflected from 

within the skin tissue after an optical 

module is touched. In other words, BAC 

is calculated either by a blood test or, 

in the future, after someone touches a 

sensor and that sensor calculates the 

BAC level in the person’s blood. 

NHTSA acknowledges that people may 

be affected by alcohol at levels below 

the legal limit used in most States (.08 

g/dL), which is why the agency noted 

above that there are still crashes where 

alcohol is involved, but the driver’s 

BAC was lower than the legal limit. 

NHTSA discusses each of these 

measurements and the vehicle 

technologies that can measure them 

later in this document. 

Drugged Driving 

Drugged driving, though important to 

prevent, is not included in the scope of 

this advance notice of proposed 

rulemaking. There are several 

complexities to understanding drugged 

or drug-involved driving.35 To begin, 

the term drugs can refer to over-thecounter medications, prescription 

medications, and illicit drugs. Also, the 

mere presence of a drug in a person’s 

system does not necessarily indicate 

impairment. Currently, most 

information collected on drugs within 

the driving context can provide 

information only on whether a driver is 

‘‘drug positive.’’ 36 The presence of 

some drugs can remain in the body a 

considerable time after use, so presence 

at any point does not necessarily mean 

the person was or remains impaired by 

the drug.37 For some drivers, certain 

prescribed medications, which may be 

included in a positive drug test result, 

may be necessary for safe driving. 

Further, there are a wide range of 

drugs other than alcohol that can be 

used by drivers. There is limited 

research on crash risk and how each 

specific drug affects driving related 

skills, and the technology and testing 

protocols are not mature in the driving 

context. Today’s knowledge about the 

effects of any drug other than alcohol on 

driving performance remains 

insufficient to draw connections 

between their use, driving performance, 

and crash risk.38

Recently, more research has been 

directed to the effects of cannabis, and 

specifically Tetrahydrocannabinol 

(THC), the active component of 

cannabis that can cause impairing 

effects on driving that might lend 

themselves to the development of THCimpaired driving detection techniques, 

like those that have been developed by 

NHTSA for use by law enforcement for 

alcohol-impaired driving.39 40 However, 

many of these effects may also be 

caused by alcohol, other drugs, and 

other impairment states like distraction, 

drowsiness, and incapacitation. Current 

knowledge about the effects of cannabis 

on driving is insufficient to allow 

specification of a simple measure of 


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41Compton, R. (2017). Marijuana-Impaired 

Driving—A Report to Congress. DOT HS 812 440. 

Washington, DC. NHTSA. 

42 78 FR 24,817 (proposed April 26, 2013). VisualManual NHTSA Driver Distraction Guidelines for 

In-Vehicle Electronic Devices. 

43 Klauer, S.G., Dingus, T.A., Neale, V.L., 

Sudweeks, J.D., & Ramsey, D.J. (2006). The impact 

of driver inattention on near-crash/crash risk: An 

analysis using the 100-car naturalistic driving study 

data (No. DOT HS 810 594). United States. 

Department of Transportation. National Highway 

Traffic Safety Administration. 

44 Young, R. (2012). Cognitive distraction while 

driving: A critical review of definitions and 

prevalence in crashes. SAE International journal of 

passenger cars-electronic and electrical systems, 

5(2012–01–0967), 326–342. 

45Regan, M.A., Lee, J.D., & Young, K. (2008). 

Driver distraction: Theory, effects, and mitigation. 

CRC press. 

46 Young, K. & Regan, M. (2007). Driver 

distraction: A review of the literature. In: I.J. Faulks, 

M. Regan, M. Stevenson, J. Brown, A. Porter & J.D. 

Irwin (Eds.). Distracted driving. Sydney, NSW: 

Australasian College of Road Safety. Pages 379– 

405.) 

47Papantoniou, P., Papadimitriou, E., & Yannis, 

G. (2017). Review of driving performance 

parameters critical for distracted driving research. 

Transportation research procedia, 25, 1796–1805. 

48Caird, J.K., Johnston, K.A., Willness, C.R., 

Asbridge, M., & Steel, P. (2014). A meta-analysis of 

the effects of texting on driving. Accident Analysis 

& Prevention, 71, 311–318. 

49SHRP2 large scale data collection effort. Data 

were collected from over 3,000 drivers. For more 

information see: https://www.fhwa.dot.gov/goshrp2/ 

Solutions/All/NDS/Concept_to_Countermeasure__

Research_to_Deployment_Using_the_SHRP2_

Safety_Data. 

50 Dingus, T.A., Guo, F., Lee, S., Antin, J.F., Perez, 

M., Buchanan-King, M., & Hankey, J. (2016). Driver 

crash risk factors and prevalence evaluation using 

naturalistic driving data. Proceedings of the 

National Academy of Sciences, 113(10), 2636–2641. 

51Owens, J.M., Dingus, T.A., Guo, F., Fang, Y., 

Perez, M., & McClafferty, J. (2018). Crash risk of cell 

phone use while driving: A case-crossover analysis 

of naturalistic driving data. AAA Foundation for 

Traffic Safety. https://aaafoundation.org/wpcontent/uploads/2018/01/CellPhoneCrashRisk_

FINAL.pdf. 

52NHTSA. (2012). Blueprint for ending distracted 

driving (Report No. DOT HS 811 629). 

www.nhtsa.gov/sites/nhtsa.dot.gov/files/ 

811629.pdf. 

53https://www.ghsa.org/state-laws/issues/ 

distracted%20driving. 

54Chaudhary, N.K., Casanova-Powell, T.D., 

Cosgrove, L., Reagan, I., & Williams, A. (2014, 

March). Evaluation of NHTSA distracted driving 

demonstration projects in Connecticut and New 

York (Report No. DOT HS 81 635). National 

Highway Traffic Safety Administration. 

driving impairment outside of 

controlled conditions.41

Given these challenges, the agency is 

not yet considering developing 

performance requirements and a FMVSS 

for drug impaired driving. 

Distracted Driving 

NHTSA defines ‘‘driver distraction’’ 

as inattention that occurs when drivers 

divert their attention away from the 

driving task to focus on another 

activity.42 In general, distractions derive 

from a variety of sources including 

electronic devices, such as navigation 

systems and mobile phones, as well as 

conventional distractions such as sights 

or events external to the vehicle, 

interactions with passengers, and eating 

or drinking. These distracting tasks can 

affect drivers in different ways, and can 

be categorized into the following types: 

—Visual distraction: Tasks that require 

or cause the driver to look away from 

the roadway to visually obtain 

information. 

—Manual distraction: Tasks that require 

or cause the driver to take a hand off 

the steering wheel and manipulate a 

device or object. 

—Cognitive distraction: Tasks that 

require or cause the driver to divert 

their mental attention away from the 

driving task. 

Research has shown that eyes-off-road 

time provides an objective measure of 

visual distraction, which has a 

demonstrated relationship with crash 

risk. Analyses of naturalistic data have 

shown that eyes-off-road times greater 

than 2.0 seconds have been shown to 

increase crash risk at a statistically 

significant level. Further, the risk of a 

crash or near-crash event increases 

rapidly as eyes-off-road time increases 

above 2.0 seconds.43 There has been 

little agreement in the field regarding 

how to identify and measure cognitive 

distraction, however.44

Distraction can negatively affect 

driving performance in various ways 

depending on the type(s) of 

distraction(s), the demands of the 

driving task and the secondary task(s), 

and other factors. These effects can 

include decrements to reaction time, 

hazard detection, lateral control (i.e., 

lane-keeping), and longitudinal control 

(e.g., speed or following gap), as well as 

changes to eye movements (e.g., glance 

patterns, eyes-off-road time), and driver 

workload.45 46 47 For example, a metaanalysis aggregating the results of 18 

simulator experiments and naturalistic 

driving studies reported that typing or 

reading text messages while driving 

significantly slowed reaction time, 

increased lane deviations, and increased 

eyes-off-road time.48

These degradations in driving 

performance due to distraction have 

been shown to translate into an 

increased risk of crash or near-crash 

involvement. An analysis of the second 

Strategic Highway Research Program 

(SHRP2) Naturalistic Driving Study 49

found that, when compared to alert and 

attentive driving, the odds of a crash 

were doubled when a driver was 

distracted, with secondary tasks that 

divert the driver’s eyes away from the 

forward roadway having the largest 

multiplicative increase in crash risk 

(e.g., dialing a handheld mobile phone 

increased crash risk by 12.2x, reading/ 

writing increased crash risk by 9.9x, and 

reaching for a non-mobile device 

increased crash risk by 9.1x).50 A 

similar study found that the use of 

handheld mobile phones in general, and 

specifically performing tasks with visual 

and manual elements (such as texting), 

were significantly associated with 

increased crash involvement.51

Outside of naturalistic driving 

studies, the role of distraction in crashes 

can be difficult to determine because 

pre-crash distractions often leave no 

evidence for law enforcement officers or 

crash investigators to observe, and 

drivers are often reluctant to admit to 

having been distracted prior to a crash. 

A NHTSA analysis of causal factors for 

fatal and non-fatal injuries estimates 

that 29 percent of fatal and non-fatal 

injuries are due to distraction. This 

estimate is over three times larger than 

the police-reported share of fatal crashes 

involving distraction (8.2% of all traffic 

fatalities in 2021, as reported in the 

Fatality Analysis Reporting System 

(FARS)). The difference between these 

values reflects the large role that 

underreporting of distraction plays in 

identifying distraction as a traffic safety 

risk. Distraction-affected crashes are a 

relatively new measure that focuses on 

distractions that are most likely to 

influence crash involvement, such as 

dialing a mobile phone or texting, and 

distraction by an outside person/ 

event.52 It is also worth noting that 

many studies on distracted driving and 

its consequences were conducted prior 

to the proliferation of smartphones, 

navigation apps and devices, and builtin technologies. Consequently, it is 

possible that distraction-related crashes 

will escalate as the prevalence, 

diversity, and use of new technologies 

continue to increase. 

Currently, text messaging is banned 

for drivers in 48 States, handheld 

mobile phone use is prohibited in 31 

States (e.g., hands-free laws), and 36 

States prohibit all mobile phone use by 

novice drivers.53 When paired with high 

visibility enforcement campaigns, 

mobile phone and text messaging laws 

were shown to reduce drivers’ use of 

handheld mobile phones in several pilot 

programs.54

Drowsy Driving 

Drowsiness is ‘‘the intermediate state 

between wakefulness and sleep as 

defined electro-physiologically by the 

pattern of brain waves (e.g., 

electroencephalogram—EEG), eye 


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55 Johns, M.W. (2000). A sleep physiologist’s view 

of the drowsy driver. Transportation research part 

F: traffic psychology and behaviour, 3(4), 241–249. 

56https://www.cdc.gov/sleep/features/drowsydriving.html. 

57 Goel, N., Rao, H., Durmer, J.S., & Dinges, D.F. 

(2009, September). Neurocognitive consequences of 

sleep deprivation. In Seminars in neurology (Vol. 

29, No. 04, pp. 320–339). 

58Fairclough SH, Graham R. Impairment of 

driving performance caused by sleep deprivation or 

alcohol: A comparative study. Human Factors. 

1999; 41(1):118–128. 

59Soares, S., Monteiro, T., Lobo, A., Couto, A., 

Cunha, L., & Ferreira, S. (2020). Analyzing driver 

drowsiness: From causes to effects. Sustainability, 

12(5), 1971. 

60 Kozak, K., Curry, R., Greenberg, J., Artz, B., 

Blommer, M., & Cathey, L. (2005, September). 

Leading indicators of drowsiness in simulated 

driving. In Proceedings of the Human Factors and 

Ergonomics Society Annual Meeting (Vol. 49, No. 

22, pp. 1917–1921). 

61Blaivas, A. J., Patel, R., Hom, D., Antigua, K., 

& Ashtyani, H. (2007). Quantifying microsleep to 

help assess subjective sleepiness. Sleep medicine, 

8(2), 156–159. 

62Thiffault, P., & Bergeron, J. (2003). Monotony 

of road environment and driver fatigue: a simulator 

study. Accident Analysis & Prevention, 35(3), 381– 

391. 

63Electrocardiogram (EKG or ECG). 

64Electroocoulogram (EOG). 

65Albadawi, Y., Takruri, M., & Awad, M. (2022). 

A review of recent developments in driver 

drowsiness detection systems. Sensors, 22(5), 2069. 66 De Gennaro, L., Ferrara, M., Curcio, G., & 

Cristiani, R. (2001). Antero-posterior EEG changes 

during the wakefulness–sleep transition. Clinical 

neurophysiology, 112(10), 1901–1911. 67Stancin, I., Cifrek, M., & Jovic, A. (2021). A 

review of EEG signal features and their application 

in driver drowsiness detection systems. Sensors, 

21(11), 3786. 68Hanowski, R.J., Bowman, D., Alden, A., 

Wierwille, W.W., & Carroll, R. (2008). PERCLOS+: 

Development of a robust field measure of driver 

drowsiness. In 15th World Congress on Intelligent 

Transport Systems and ITS America’s 2008 Annual 

Meeting. 

69Murata, A., Ohta, Y., & Moriwaka, M. (2016). 

Multinomial logistic regression model by stepwise 

method for predicting subjective drowsiness using 

performance and behavioral measures. In 

Proceedings of the AHFE 2016 International 

Conference on Physical Ergonomics and Human 

Factors, July 27–31, 2016, Walt Disney World®, 

Florida, USA (pp. 665–674). 

70Watson, A., & Zhou, G. (2016, June). Microsleep 

prediction using an EKG capable heart rate monitor. 

In 2016 IEEE First International Conference on 

Connected Health: Applications, Systems and 

Engineering Technologies (CHASE) (pp. 328–329). 

IEEE. 

71de Naurois, C.J., Bourdin, C., Stratulat, A., Diaz, 

E., & Vercher, J.L. (2019). Detection and prediction 

of driver drowsiness using artificial neural network 

models. Accident Analysis & Prevention, 126, 95– 

104. 

72Berka, C., Levendowski, D., Westbrook, P., 

Davis, G., Lumicao, M.N., Ramsey, C., . . . & 

Olmstead, R.E. (2005, July). Implementation of a 

closed-loop real-time EEG-based drowsiness 

detection system: Effects of feedback alarms on 

performance in a driving simulator. In 1st 

International Conference on Augmented Cognition, 

Las Vegas, NV (pp. 151–170). 

73Fairclough, S.H., & van Winsum, W. (2000). 

The influence of impairment feedback on driver 

behavior: A simulator study. Transportation human 

factors, 2(3), 229–246. 

74Arimitsu, S., Sasaki, K., Hosaka, H., Itoh, M., 

Ishida, K., & Ito, A. (2007). Seat belt vibration as a 

stimulating device for awakening drivers. IEEE/ 

ASME Transactions on mechatronics, 12(5), 511– 

518. 

75 Gaspar, J.G., Brown, T.L., Schwarz, C.W., Lee, 

J.D., Kang, J., & Higgins, J.S. (2017). Evaluating 

driver drowsiness countermeasures. Traffic injury 

prevention, 18(sup1), S58–S63. 

76 In the medical field, the National Institutes of 

Health (NIH) established a program nearly 15 years 

ago to study behavior change and try to identify the 

most successful mechanisms that result in the most 

behavior change. They understood the problem and 

developed interventions, but they really did not 

understand why the intervention worked for some 

but not others. See https://scienceofbehavior

change.org/what-is-sobc/ for an example of a NIH 

project focusing on the science behind changing 

human behaviors. 

movements, and muscle activity.’’ 55

Driver drowsiness has a variety of 

biological contributors, including 

sleeplessness or sleep deprivation, 

changes in sleep patterns, untreated 

sleep disorders, and use of drugs with 

sedative effects, including alcohol.56

Driver drowsiness can lead to 

impairments in cognitive and 

psychomotor speed, attentional 

distribution, vigilance, and working 

memory.57

Within the driving context, 

performance measures that have shown 

drowsiness-related decrements include 

lane keeping and lane departures,58

slower driving speed and decreased 

speed stability,59 and longer reaction 

times.60 Drowsiness can progress into 

microsleep and sleep events, in which 

the driver may experience cognitive 

and/or visual lapses of increasing 

duration, posing increasingly serious 

risks of crash involvement.61 Situational 

factors such as increasing time on task 

and monotony of driving environment 

can contribute to driver drowsiness.62

While driver drowsiness cannot be 

measured directly, it can be indirectly 

detected and measured using both 

objective and subjective measures. 

Objective measures related to driver 

drowsiness include physiological 

signals of brain activity (e.g., EEG, 

EKG,63, EOG 64), other biological 

markers (e.g., heart rate, respiration, 

galvanic skin response), measures based 

on observations of the driver (e.g., head 

pose, eye closure, blink rate), and 

vehicle control measures (e.g., steering 

wheel angle, lane departures, speed 

variation). Using multiple measures in 

combination may increase the accuracy 

and reliability of drowsiness 

detection.65

Among brain activity measures, EEG 

is most frequently used to measure brain 

states, including drowsiness.66 While 

factors such as individual differences, 

time of day, and other non-drowsiness 

related brain activity can be 

confounding factors, signal markers in 

EEG data can indicate the presence and 

degree of drowsiness.67 While EEG and 

some other direct brain measures are 

advancing in their ease of use and 

portability, they are generally not 

feasible for in-vehicle use at the present 

time. 

Camera-based-systems, however, are 

increasingly feasible and common in 

vehicles. Camera-based systems have 

the potential to measure a wide array of 

driver head and face characteristics that 

may be indicative of drowsiness, 

including driver head pose, driver gaze 

activity (e.g., number and distribution of 

glances), the percentage of time the 

driver’s eyes are closed (i.e., 

PERCLOS 68), blink speed, eye closure 

duration, yawns, and other facial 

expressions. 

As noted previously, driver 

drowsiness tends to become 

progressively more pronounced over 

time. The progressive nature of driver 

drowsiness means that it is possible to 

estimate a driver’s future drowsiness 

state—seconds or even more than a 

minute into the future—based on their 

current drowsiness state. Researchers 

have used various physiological and 

behavioral measures to develop models 

to predict drivers’ subjective 

drowsiness,69 predict the occurrence of 

microsleeps,70 and predict drowsiness 

as determined by coders looking at 

video of drivers’ faces.71 While limited 

research exists to demonstrate the 

feasibility of drowsiness state prediction 

under real-world driving conditions, 

further developments in drowsiness 

prediction could allow vehicles to 

provide alerts and interventions to 

reduce the risks of drowsy driving 

before they become severe. 

As the detection and prediction of 

driver drowsiness within a vehicle 

becomes increasingly feasible, it is 

possible to consider potential vehiclebased countermeasures to reduce risk. 

While there is limited research 

investigating interventions to reduce 

drowsy driving risks, evidence suggests 

that auditory,72 visual,73 and seat belt 

vibration 74 warnings can help to 

improve drowsy drivers’ driving 

performance, and that there may be 

benefits to multi-staged warnings 

relative to single-stage warnings.75

B. Many Different Behavioral Strategies 

Exist, Yet Impaired Driving Persists 

Alcohol-impaired driving is a 

behavioral issue, and in general, 

changing human behavior is particularly 

challenging.76 NHTSA has made 

considerable progress in behavioral 

research to advance the knowledge and 

understanding of the physiological 


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77https://www.nhtsa.gov/book/countermeasures/ 

alcohol-and-drug-impaired-driving/strategiesreduce-impaired-driving. 

78See https://www.nhtsa.gov/book/ 

countermeasures/alcohol-and-drug-impaireddriving/countermeasures. 

79 Id. 

80 49 U.S.C. 30111(a). 

81 49 U.S.C. 30102(a)(9). 

82Section 30102(a)(10). 

83Section 30111(b)(1). 

84Section 30111(b)(3)–(4). 

85 49 CFR 1.95. 

86See, e.g., Paccar, Inc. v. Nat’l Highway Traffic 

Safety Admin., 573 F.2d 632, 634 n.5 (‘‘ ‘Practicable’ 

is defined to require consideration of all relevant 

factors, including technological ability to achieve 

the goal of a particular standard as well as 

consideration of economic factors.’’) (citations and 

quotations omitted). 

87Pac. Legal Found. v. Dep’t of Transp., 593 F.2d 

1338, 1345 (D.C. Cir. 1979) (noting in reference to 

practicable and meet the need for safety, that ‘‘the 

agency cannot fulfill its statutory responsibility 

unless it considers popular reaction.’’). 

88Simms v. Nat’l Highway Traffic Safety Admin., 

45 F.3d 999, 1011 (6th Cir. 1995). 

89Pac. Legal Found., 593.F.2d at 1346. The court 

also noted that the Secretary could reasonably 

anticipate consumers to be more willing to accept 

airbags than automatic seatbelts and seatbelt 

interlocks because airbags impose less on the driver 

and research indicated a lower deactivation rate for 

airbags than interlock systems. 

90See, 82 FR 3854, 3920. Due to the nature of the 

technology, consumer acceptance was a key factor 

discussed in the 2017 NPRM on vehicle-to-vehicle 

(V2V) technology. NHTSA also conducted 

significant research into consumer acceptance and 

beliefs about V2V technology. 

91 49 U.S.C. 30122. 

92Letter to Schaye (9/9/19) (‘‘The ‘‘make 

inoperative’’ provision does not apply vehicle 

owners, and these owners are not precluded from 

modifying their vehicle by NHTSA’s statutes or 

regulations. State and local laws, however, may 

impact whether an owner may use a vehicle they 

have modified in a particular jurisdiction.’’), 

available at https://www.nhtsa.gov/interpretations/ 

571108-ama-schaye-front-color-changing-light. 

93 Infrastructure Investment and Jobs Act, Public 

Law 117–58, section 24220 (2021). 

94Section 24220(c). 

95Section 24220(c), (e). 

96See, e.g., Motor Vehicle Mfrs. Assn. of United 

States, Inc. v. State Farm Mut. Automobile Ins. Co., 

463 U.S. 29, 55 (1983) (‘‘The agency is correct to 

look at the costs as well as the benefits of Standard 

208 . . . When the agency reexamines its findings 

as to the likely increase in seat belt usage, it must 

Continued 

effects of alcohol impairment on 

driving. Additionally, NHTSA has taken 

a multi-pronged approach to trying to 

eliminate alcohol-impaired driving. 

Four basic strategies are used to reduce 

impaired driving crashes and driving 

under the influence: 

1. Deterrence: enact, publicize, 

enforce, and adjudicate laws prohibiting 

impaired driving so people choose not 

to drive impaired; 

2. Prevention: reduce drinking and 

drug use to keep drivers from becoming 

impaired; 

3. Communications and outreach: 

inform the public of the dangers of 

impaired driving and establish positive 

social norms that make driving while 

impaired unacceptable; and 

4. Alcohol and drug treatment: reduce 

alcohol and drug dependency or 

addiction among drivers.77

NHTSA uses and encourages a variety 

of different behavioral strategies, 

focusing on those strategies that are 

demonstrably effective.78 Some 

strategies, like laws, enforcement, 

criminal prosecution, and offender 

treatment and monitoring, have a 

deterrent effect. Other strategies focus 

on prevention, intervention, 

communications, and outreach.79

C. NHTSA’s Authority 

The National Traffic and Motor 

Vehicle Safety Act provides NHTSA 

with broad authority to address motor 

vehicle safety problems like driver 

impairment. Under the National Traffic 

and Motor Vehicle Safety Act (49 U.S.C. 

30101 et seq.) (Safety Act), the Secretary 

of Transportation is responsible for 

prescribing motor vehicle safety 

standards that are practicable, meet the 

need for motor vehicle safety, and are 

stated in objective terms.80 ‘‘Motor 

vehicle safety’’ is defined in the Safety 

Act as ‘‘the performance of a motor 

vehicle or motor vehicle equipment in 

a way that protects the public against 

unreasonable risk of accidents occurring 

because of the design, construction, or 

performance of a motor vehicle, and 

against unreasonable risk of death or 

injury in an accident, and includes 

nonoperational safety of a motor 

vehicle.’’ 81 ‘‘Motor vehicle safety 

standard’’ means a minimum standard 

for motor vehicle or motor vehicle 

equipment performance.82 When 

prescribing such standards, the 

Secretary must consider all relevant, 

available motor vehicle safety 

information.83 The Secretary must also 

consider whether a proposed standard is 

reasonable, practicable, and appropriate 

for the types of motor vehicles or motor 

vehicle equipment for which it is 

prescribed and the extent to which the 

standard will further the statutory 

purpose of reducing traffic crashes and 

associated deaths.84 The responsibility 

for promulgation of FMVSS is delegated 

to NHTSA.85

To meet the Safety Act’s requirement 

that standards be ‘‘practicable,’’ NHTSA 

must consider several factors, including 

technological and economic 

feasibility 86 and consumer 

acceptance.87 Technological feasibility 

considerations counsel against 

standards for which ‘‘many technical 

problems have been identified and no 

consensus exists for their resolution 

. . . .’’ 88 However, it does not require 

that the technology be developed, 

tested, and ready for deployment at the 

time the standard is promulgated. 

Economic feasibility considerations 

focus on whether the cost on industry 

to comply with the standard would be 

prohibitive. Finally, NHTSA must 

consider consumer acceptance. In 

particular, the U.S. Court of Appeals for 

the D.C. Circuit has noted that ‘‘motor 

vehicle safety standards cannot be 

considered practicable unless we know 

. . . that motorists will avail themselves 

of the safety system. And it would be 

difficult to term ‘practicable’ a system 

. . . that so annoyed motorists that they 

deactivated it.’’ 89 NHTSA also 

understands that if consumers do not 

accept a required safety technology, the 

technology will not deliver the safety 

benefits that NHTSA anticipates.90

The Safety Act also contains a ‘‘make 

inoperative’’ provision, which prohibits 

certain entities from knowingly 

modifying or deactivating any part of a 

device or element of design installed in 

or on a motor vehicle in compliance 

with an applicable FMVSS.91 Those 

entities include vehicle manufacturers, 

distributors, dealers, rental companies, 

and repair businesses. Notably, the 

make inoperative prohibition does not 

apply to individual vehicle owners.92

While NHTSA encourages individual 

vehicle owners not to degrade the safety 

of their vehicles or equipment by 

removing, modifying, or deactivating a 

safety system, the Safety Act does not 

prohibit them from doing so. This 

creates a potential source of issues for 

solutions that lack consumer 

acceptance, since individual owners 

would not be prohibited by Federal law 

from removing or modifying those 

systems (i.e., using defeat mechanisms). 

Section 24220 of BIL, ‘‘Advanced 

Impaired Driving Technology,’’ 93

directs NHTSA to issue a final rule 

prescribing an FMVSS ‘‘that requires 

passenger motor vehicles manufactured 

after the effective date of that standard 

to be equipped with advanced drunk 

and impaired driving prevention 

technology.’’ 94 NHTSA is required to 

issue such a rule only if it would meet 

the criteria in section 30111 of the 

Safety Act.95 As explained above, those 

criteria include, among other things, 

that an FMVSS be objective, practicable, 

and meet the need for motor vehicle 

safety. In analyzing these criteria, 

NHTSA must balance benefits and costs 

and consider safety as the preeminent 

factor in its considerations.96


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also reconsider its judgment of the reasonableness 

of the monetary and other costs associated with the 

standard. In reaching its judgment, NHTSA should 

bear in mind that Congress intended safety to be the 

preeminent factor under the Motor Vehicle Safety 

Act.’’). 

97Section 24220(b). 

98FMVSS Nos. 208, ‘‘Occupant crash protection,’’ 

and 212, ‘‘Windshield mounting,’’ use a similar 

definition for completely passive protection 

systems for occupants. 49 CFR 571.208, 571.212. 

DADSS has also viewed the term similarly. See 

Report to Congress on Progress In-Vehicle Alcohol 

Detection Research, October 1, 2019 through 

September 30, 2020. 

99Section 24220 (b)(3), referring to 49 U.S.C. 

32101(consumer information statutes). 

100Section 24220 (e)(2). The report must also 

describe the deployment of advanced drunk and 

impaired driving prevention technology in vehicles, 

any information relating to the ability of vehicle 

manufacturers to include advanced drunk and 

impaired driving prevention technology in new 

passenger motor vehicles, and an anticipated 

timeline for prescribing the Federal motor vehicle 

safety standard. 

101Section 24220 (e)(2)–(3). If, after ten years, 

NHTSA has not promulgated the FMVSS required 

by this subsection, the report must state the reasons 

why the FMVSS was not finalized, the barriers to 

finalizing the FMVSS, and recommendations to 

Congress to facilitate the FMVSS. 

102Blincoe, L., Miller, T., Wang, J.S., Swedler, D., 

Coughlin, T., Lawrence, B., Guo, F. Klauer, S., & 

Dingus, T. (2023, February). The economic and 

societal impact of motor vehicle crashes, 2019 

(Revised) (Report No. DOT HS 813 403). National 

Highway Traffic Safety Administration. 

103See, for example, NHTSA Estimates: Traffic 

Deaths Third Quarter of 2022 | NHTSA. 

104Crash Stats: Early Estimate of Motor Vehicle 

Traffic Fatalities for the First Quarter of 2023 

(dot.gov) 

105NHTSA (2023). Early Estimate of Motor 

Vehicle Traffic Fatalities for the First Half (January– 

June) of 2023. Report No. DOT HS 813 514. 

National Highway Traffic Safety Administration: 

Washington, DC. (September) 

Section 24220 defines ‘‘Advanced 

Drunk and Impaired Driving 

Technology’’ as a system that 

(A) can— 

(i) passively monitor the performance 

of a driver of a motor vehicle to 

accurately identify whether that driver 

may be impaired; and 

(ii) prevent or limit motor vehicle 

operation if an impairment is detected; 

or 

(B) can— 

(i) passively and accurately detect 

whether the blood alcohol concentration 

of a driver of a motor vehicle is equal 

to or greater than the blood alcohol 

concentration described in section 

163(a) of title 23, United States Code; 

and 

(ii) prevent or limit motor vehicle 

operation if a blood alcohol 

concentration above the legal limit is 

detected; or 

(C) is a combination of systems 

described in subparagraphs (A) and 

(B).97

This means that a final rule could 

require vehicles be equipped with a 

system that detects whether the driver is 

impaired (an impairment-detection 

system); a system that detects whether 

the driver’s BAC is above a specified 

threshold (a BAC-detection system); or a 

combination of these two systems. 

These options and the technology that 

might fulfill each option are discussed 

in greater detail later in this document. 

Section 24220 further requires that 

the ‘‘Advanced Drunk and Impaired 

Driving Technology’’ ‘‘passively’’ 

monitor performance or detect BAC. For 

the purposes of this advance notice of 

proposed rulemaking, NHTSA uses the 

term ‘‘passive’’ to mean that the system 

functions without direct action from 

vehicle occupants.98 As such, systems 

that require a ‘‘directed breath’’ towards 

a sensor, such as the current DADSS 

reference designs (discussed later in this 

document) or a breathalyzer that a 

driver must breathe into in order for the 

system to detect alcohol would not be 

considered ‘‘passive’’ because these 

designs require a vehicle occupant to 

take direct action (i.e., directed breath) 

for the system to function. 

Section 24220 does not require that a 

final rule give manufacturers the option 

of choosing between an impairmentdetection and a BAC-detection system. 

NHTSA understands the term 

‘‘impairment,’’ for the purposes of 

section 24220, to refer to alcohol-related 

impairment as well as other types of 

driver impairment. Of course, regardless 

of how the term ‘‘impairment’’ is 

construed for the purposes of section 

24220, NHTSA also has the authority 

under the Safety Act to issue an FMVSS 

addressing any type of driver 

impairment if the standard would 

satisfy the criteria in section 30111 of 

the Safety Act. 

The new FMVSS would be required to 

apply to new vehicles that carry 12 or 

fewer individuals, not including 

motorcycles or trucks not designed 

primarily to carry its operator or 

passengers.99

BIL also establishes a series of 

deadlines and requirements for NHTSA 

to report to Congress if those deadlines 

are not met. The legislation directs 

NHTSA to issue a final rule (if it would 

meet the section 30111 criteria) not later 

than November 15, 2024. If NHTSA 

does not issue a rule by this date, it 

must submit a report to Congress 

explaining (among other things) the 

reasons for not issuing a final rule.100

NHTSA must submit such reports 

annually until it issues a final rule or 

ten years has expired, from the date of 

enactment, whichever comes first.101

III. Advanced Drunk and Impaired 

Driving Prevention Safety Problem 

The overall safety problem caused by 

various types of states of impaired 

driving is substantial, and those 

impaired states are part of the causal 

chain for a large percentage of crashes 

in the United States. A recent NHTSA 

report, ‘‘The Economic and Societal 

Impact of Motor Vehicle Crashes 

(2019),’’ reviewed 2019 data and 

described the state of safety prior to the 

COVID–19 pandemic.102 In 2019, the 

lost lives and costs on our society 

stemming from motor vehicle crashes 

were enormous—36,500 people were 

killed, 4.5 million people were injured, 

and the economic costs of these crashes 

totaled $340 billion. Of this $340 

billion, nearly half ($167 billion) 

resulted from alcohol-involved and 

distracted-driving crashes alone. 

Furthermore, the overall safety problem 

has only gotten worse during the 

COVID–19 pandemic, as NHTSA has 

confirmed that the increases in 

fatalities, injuries, and risky driving that 

the country experienced in 2020 

continued through the first two quarters 

of 2022.103 Recent first quarter 

projections for traffic fatalities in 

2023 104 have reversed the trend, with 

NHTSA estimating an overall fatality 

decrease of about 3.3 percent as 

compared to the same time period in 

2022. The second quarter of 2023 would 

represent the fifth straight quarterly 

decline in fatalities after seven 

consecutive quarters of year-to-year 

increases in fatalities, beginning with 

the third quarter of 2020. Please see 

Graph 2. Fatalities by Quarter 105 below. 

While this is encouraging overall, far too 

many people continue to die on our 

roads every year, and drunk and 

impaired driving crashes still result in 

significant numbers of those lives lost. 


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106Blincoe et al., 2023 Blomberg, R., Peck, R.C., 

Moskowitz, H., Burns, M., & Fiorentino, D. (2005, 

September). Crash risk of alcohol-involved driving: 

A case-control study. Dunlap and Associates; 

Blincoe et al., 2023. 

The introduction to this advance 

notice of proposed rulemaking states 

that NHTSA is considering focusing 

primarily on alcohol impairment, both 

because of the mandate in the BIL and 

because alcohol impairment has the 

tangible strategies developed to identify 

it. But the agency requests comment on 

this focus because of the danger that 

other impaired states cause during the 

driving task and because some options 

described in later sections provide the 

opportunity to resolve multiple states of 

impairment with the same technological 

solution. In this section, NHTSA will 

discuss the drunk, drowsy, and 

distracted driving states that account for 

most of the fatalities and crashes related 

to impaired driving. NHTSA has 

presented the safety problem in this way 

because the agency is interested in 

proceeding with whatever practical 

course of action results in the most lives 

saved and injuries prevented in the 

shortest amount of time, regardless of 

what impaired driving state is the root 

cause. Additionally, NHTSA believes 

the public should be aware of the 

overall safety problem associated with 

driver impairment so that it may have 

adequate information when responding 

to NHTSA’s questions about whether 

focusing on alcohol-impairment is the 

best path forward to achieve improved 

motor vehicle safety and protect the 

public from the complex behavioral 

issues that result in driver impairment. 

For this analysis, we consider the 

three categories of impaired driving 

safety impacts most likely to be 

ameliorated by a safety countermeasure 

arising from this ANPRM: drunk 

driving, drowsy driving, and distracted 

driving. As mentioned in the 

introduction, NHTSA hopes that the 

agency’s approach may yield additional 

safety benefits by considering all 

technologies that have the potential to 

mitigate or prevent impaired driving 

fatalities and injuries. 

The safety data on drunk driving, and 

the confidence in those data, are much 

more substantial than data on other 

types of impaired driving, and drunk 

driving results in serious loss of life, 

injury, and economic costs to the 

public. This section will present 

estimates of annual fatalities and 

injuries due to drunk, drowsy, and 

distracted driving. 

It is also worth noting that in other 

recent rulemakings, NHTSA decided not 

to use post-2019 data because the 

agency was not yet sure whether the 

disturbing uptick in crashes and 

fatalities was an anomaly or a trend that 

reflects a change in vehicle safety that 

would remain for more than one year or 

the foreseeable future. Analysis since 

the issuance of previous documents 

indicates that data from 2020 and 2021 

highlight a potentially dangerous trend 

in the United States of an increase in 

motor vehicle crashes and fatalities, 

which is why this advance notice of 

proposed rulemaking differs from other 

documents issued in the recent past in 

citing post-2019 data. 

A. Drunk Driving 

Per FARS, in 2021 there were 13,384 

traffic fatalities in which at least one 

driver had a BAC at or above .08 g/dL, 

(representing approximately 31 percent 

of all traffic fatalities in the United 

States). NHTSA’s process for identifying 

fatalities due to drunk driving begins by 

acknowledging that not all alcoholrelated motor vehicle fatalities and 

injuries are caused by alcohol 

consumption. In NHTSA’s fatality 

numbers reported in FARS, use of the 

term ‘‘alcohol-impaired’’ does not 

indicate that a crash or a fatality was 

caused by alcohol impairment, only that 

an alcohol-impaired driver was 

involved in the crash. That is, some of 

the crashes may have involved causative 

factors other than alcohol (e.g., one or 

multiple drivers or vehicles associated 

with speeding, reckless behavior, or 

mechanical failure). 

Critically for this advance notice of 

proposed rulemaking, NHTSA’s analysis 

has applied Blomberg et al.’s risk factors 

to estimate that alcohol is indeed a 

causal factor in 94 percent of crashes 

involving at least one driver with a BAC 

at or above .08 g/dL.106 Thus, the agency 

estimates that, among all crashes, 

fatalities, and injuries involving drivers 

that have a BAC at or above .08 g/dL, 

94 percent of them are due directly to 


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Graph 2. Fatalities by Quarter 

Fatalities by Quarter (Total and Year~over~Year Change) 

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840 Federal Register / Vol. 89, No. 4 / Friday, January 5, 2024 / Proposed Rules 

107Blincoe et al., 2023. 

108https://fred.stlouisfed.org/series/ 

USAGDPDEFAISMEI. 

109Blincoe et al., 2023. 

110National Center for Statistics and Analysis. 

(2017 October). Drowsy Driving 2015 (CrashStats 

Brief Statistical Summary. Report No. DOT HS 812 

446). Washington, DC: National Highway Traffic 

Safety Administration. 

111 Knipling, R. & Wang, J. (1994). Crashes and 

fatalities related to driver drowsiness/fatigue. 

Washington, DC: National Highway Traffic Safety 

Administration. 

112Tefft, B. (2010). The Prevalence and Impact of 

Drowsy Driving (Technical Report). Washington, 

DC: AAA Foundation for Traffic Safety. 

113Owens, J.M., Dingus, T.A.. Guo, F., Fang, Y., 

Perez, M., McClafferty, J., & Tefft, B.C. (2018). 

Prevalence of Drowsy Driving Crashes: Estimates 

from a Large-Scale Naturalistic Driving Study 

(Research Brief). Washington, DC: AAA Foundation 

for Traffic Safety. 

114See, e.g., 23 U.S.C. 402 (fund that can be used 

for any purpose); 23 U.S.C. 405(d) (priority funds, 

alcohol consumption and are thus 

within the scope of impaired driving 

countermeasures that would focus on 

the legal limit in most States (.08 g/dL). 

This yields an estimate of 

approximately 12,581 fatalities in 2021 

due to alcohol impairment. At an 

estimated comprehensive economic cost 

of approximately $12.7 million per 

fatality (adjusted to 2022 dollars using 

the GDP Implicit Price Deflator 107 108), 

fatalities in alcohol impairment-related 

crashes were associated with societal 

safety costs of approximately $160 

billion in 2021. 

B. Distracted Driving 

Historically, distracted driving 

crashes have been more difficult to 

quantify than drunk driving crashes 

because unlike BAC, distraction cannot 

yet be tested for objectively post-crash. 

However, Blincoe et al. developed and 

implemented a methodology to estimate 

both: (1) underreporting of cases 

involving distraction; and (2) the shares 

of crashes, fatalities, and injuries caused 

by distraction.109 NHTSA applies the 

results of Blincoe et al. here to 2021 

FARS data to estimate fatalities in 2021 

due to distracted driving. 

Blincoe et al. estimate that 28.9 

percent of all crashes (and injuries of all 

severities within crashes) are due to 

distraction. Based on this estimate, the 

agency estimates that distracted driving 

caused 12,405 fatalities in 2021. This 

represents a societal safety cost of 

approximately $158 billion, an 

economic estimate of the loss of life. 

Dingus et al. report that 

approximately seven percent of cases of 

distraction also involve some form of 

impairment. In turn, it is appropriate to 

assume that there is at least some degree 

of overlap among drunk driving and 

distracted driving fatalities. Thus, the 

combined safety problem associated 

with drunk driving and distracted 

driving is likely to be somewhat smaller 

than the sum of the individual estimates 

above (i.e., distracted driving fatalities 

in 2021 not jointly caused by alcohol 

would be up to 7% lower than the 

estimate of 12,405 fatalities above). 

C. Drowsy Driving 

Drowsy driving is more difficult to 

quantify than drunk driving because, 

among other factors, there is not 

currently an accepted standard 

definition of drowsiness in a driving 

context, nor a threshold to define 

drowsiness as a causal factor in motor 

vehicle crashes. In turn, the level of 

drowsiness-related crashes and injuries 

is subject to faulty measurement, with 

underreporting more likely than 

overreporting. In defining the drowsy 

driving safety problem, NHTSA begins 

with estimates based on police-reported 

drowsiness as a contributing factor, and 

then considers external estimates of 

underreporting. 

To estimate fatalities in 2021 

associated with drowsy driving, the 

agency analyzes fatalities reported in 

FARS in which at least one driver was 

reported as asleep or drowsy: this 

revealed 684 fatalities, or approximately 

1.6 percent of total annual fatalities. 

Applying estimates of the 

comprehensive economic costs of injury 

from the last section, NHTSA estimates 

that reported fatalities associated with 

drowsy driving in 2021 represent a 

social cost of approximately $9 billion. 

NHTSA’s annual estimates of 

fatalities associated with drowsy driving 

are consistent with other NHTSA 

estimates (e.g., annual drowsinessrelated fatality estimates in NHTSA’s 

‘‘Drowsy Driving 2015’’).110 111 However, 

the estimates are lower than other 

external estimates, such as Tefft, which 

estimates that one-sixth of traffic 

fatalities are associated with 

drowsiness,112 and Owens et. al which 

estimates that approximately one-tenth 

of police-reportable crashes are 

associated with drowsiness.113 NHTSA 

does not have sufficient evidence 

regarding underreporting. On the other 

hand, consistent with the discussion of 

drowsiness-related crashes and 

acknowledges that underreporting 

distracted driving above, it is a feasible 

constraint to estimating the scale of the 

that at least some fatalities caused by 

drowsy driving safety problem. are also 

caused by alcohol impairment or 

distraction (furthermore, the drowsiness 

itself could be caused by drinking, and 

the distraction itself could be caused by 

drowsiness). For this analysis, the 

agency applies its estimate as a 

conservative estimate of a significant 

safety issue (i.e., NHTSA expects the 

true annual safety costs associated with 

drowsy driving to be at least as large as 

estimated here). The agency requests 

comment and data regarding 

underreporting of drowsy driving, and 

interdependencies among drunk 

driving, distracted driving, and drowsy 

driving. 

IV. Overview of Current Efforts To 

Address Drunk and Impaired Driving 

NHTSA has a robust portfolio of 

behavioral-prevention and vehicleresearch activities focused on 

preventing drunk and impaired driving. 

NHTSA believes that the combination of 

these strategies (i.e., behavioral 

strategies and vehicle-based 

countermeasures) is necessary to move 

towards a nation where alcoholimpaired individuals are unable to drive 

vehicles and put the lives of everyone 

around them at risk by doing so. As 

discussed in the introduction, one of the 

effects that leads drivers to take such 

unacceptable risks when intoxicated is 

alcohol’s impact on their brain, 

especially in impairing judgment. 

A. State and Federal Behavioral 

Prevention Activities 

Behavioral prevention activities are 

public-oriented strategies intended to 

change the behaviors that lead to drunk 

and impaired driving. This is 

distinguished from vehicle-based 

countermeasures, which are discussed 

later in this document. To develop and 

implement these behavioral strategies, 

NHTSA collaborates with a wide array 

of national, regional, State, and local 

traffic safety partners, including those in 

the following sectors: public safety and 

criminal justice; medical, public health 

and emergency services; educators; 

parents; non-profits; traffic safety 

organizations; and academic 

institutions. More recently, NHTSA has 

expanded these partnerships to include 

substance use prevention, mental 

health, and overall wellness efforts as 

part an overall approach to address 

issues that lead to drunk and impaired 

driving. 

NHTSA’s behavioral prevention 

activities can be categorized into three 

main areas. First, NHTSA conducts 

research to identify the scope of the 

issue and develop effective evidencebased strategies to address the behaviors 

that lead to drunk and impaired driving. 

Second, NHTSA distributes Federal 

grant funds to individual States, and 

these funds are used for behavioral 

strategies.114 Each State is required to 


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specifically for impaired driving); 23 U.S.C. 154 

(open container); 23 U.S.C. 164 (repeat offender). 

115See Venkatraman, V., Richard, C.M., Magee, 

K., & Johnson, K. (2021, July). Countermeasures that 

work: A highway safety countermeasures guide for 

State Highway Safety Offices, 10th edition, 2020 

(Report No. DOT HS 813 097). National Highway 

Traffic Safety Administration. (hereinafter 

Countermeasures that work). Vehicle and 

infrastructure strategies can also reduce the 

likelihood of crashes and/or injuries sustained by 

impaired drivers and passengers, such as improved 

vehicle structures and centerline rumble strips and 

barriers. These countermeasures are outside the 

scope of this discussion. 

116 Venkatraman, V., Richard, C.M., Magee, K., & 

Johnson, K. (2021, July). Countermeasures that 

work: A highway safety countermeasures guide for 

State Highway Safety Offices, 10th edition, 2020 

(Report No. DOT HS 813 097). National Highway 

Traffic Safety Administration. 

117 23 U.S.C. 163. 

118 23 U.S.C. 161. 

119 23 U.S.C. 158. 

120 23 U.S.C. 154. 

121See https://www.ghsa.org/state-laws/issues/ 

alcohol%20impaired%20driving (last accessed 

January 5, 2023); https://www.ncsl.org/research/ 

transportation/drunken-driving.aspx (last accessed 

January 5, 2023). 

122https://www.ntsb.gov/safety/safety-studies/ 

Documents/SR1301.pdf. 

123Thomas, F.D., Blomberg R., Darrah, J., Graham, 

L., Southcott, T., Dennert, R., Taylor, E., Treffers, 

R., Tippetts, S., McKnight, S., & Berning, A. (2022, 

February). Evaluation of Utah’s .05 BAC per se law. 

DOT HS 813 233. NHTSA. 124 36 CFR 4.23. 125 If State law establishes more restrictive BAC 

limits, those more restrictive limits supersede the 

.08 g/dL limit specified in the Federal regulations. 

126 DWI and DUI are used interchangeably 

throughout this document. 

have a highway safety program, 

approved by the Secretary of 

Transportation, that is designed to 

reduce traffic crashes and the resulting 

deaths, injuries, and property damage. 

NHTSA provides grants to each State for 

their highway safety program as well as 

funds to address national priorities for 

reducing highway deaths and injuries, 

such as impaired driving programs. 

Third, NHTSA works directly with 

States and other stakeholders to 

develop, implement, and support 

effective programs and strategies to stop 

drunk and impaired driving. This 

includes demonstration projects, 

training and education for traffic safety 

professionals, and communications 

campaigns to educate the public. 

NHTSA also helps States use data to 

identify their highway safety needs and 

evaluate safety programs and activities, 

and the agency provides technical 

assistance and training to State program 

managers. 

Below we briefly discuss four of the 

main drunk and impaired driving 

behavioral strategies that help us 

execute our three main areas mentioned 

above: Deterrence; Prevention; 

Communications and outreach; and 

alcohol and drug treatment programs.115

1. Deterrence 

Deterrence includes enacting laws 

that prohibit drunk and impaired 

driving, publicizing and enforcing those 

laws, and identifying and punishing 

offenders.116 Deterrence works by 

changing a driver’s behavior through 

concern for the consequences of certain 

behaviors, such as being apprehended 

by law enforcement. Below we provide 

a brief overview of activities in these 

areas with respect to drunk and 

impaired driving, with a focus on State 

and Federal drunk driving laws and 

NHTSA’s efforts to support and develop 

training and best practices for law 

enforcement, prosecutors, judges, and 

other public safety and criminal justice 

partners. 

a. State and Federal Drunk Driving Laws 

State laws, as well as Federal law 

governing the use of motor vehicles on 

Federally owned land, prohibit 

operation of a motor vehicle when the 

driver is at or exceeds the state’s per se 

illegal limit (i.e., BAC of .08 g/dL in all 

states, except Utah which has a .05 g/ 

dL illegal limit). 

All States have enacted drunk driving 

laws. Some of these laws have been 

incentivized by Federal law, because 

significant portions of the Federal funds 

available to the States, including State 

Highway funds, are conditioned on a 

State enacting and enforcing specific 

laws related to drunk driving. This 

includes laws prohibiting operation of a 

motor vehicle with a BAC of .08 percent 

or greater; 117 laws prohibiting 

individuals under the age of 21 from 

operating a motor vehicle with a BAC of 

.02 percent or greater (zero-tolerance 

laws); 118 laws setting a minimum 

drinking age of 21; 119 and laws 

prohibiting possession of open alcohol 

beverage containers and consumption of 

alcohol in a vehicle (open-container 

laws).120 If a State does not have the 

required laws, it loses significant 

funding to which it would otherwise be 

entitled. Accordingly, all States have 

enacted such laws.121 Many States have 

also gone above and beyond the 

Federally-incentivized laws. For 

instance, on December 30, 2018, Utah 

lowered its BAC threshold to .05 g/dL 

for all drivers. Examples of other laws 

States have enacted include driver 

license revocation or suspension if 

drivers fail or refuse to take BAC tests, 

and increased penalties for repeat 

offenders or for offenders with higher 

BACs. 

The National Transportation Safety 

Board (NTSB) has recently 

recommended that NHTSA seek 

legislative authority to award incentive 

grants for States to establish a per se 

BAC limit of .05 or lower for all drivers 

who are not already required to adhere 

to lower BAC limits.122 In response to 

this recommendation, NHTSA 

published the results of preliminary 

research on the effects of Utah’s law.123

This research suggests that the .05 g/dL 

per se law has had quantifiable positive 

impacts on highway safety in Utah so 

that lower BAC thresholds may be 

effective in further reducing alcoholinvolved crashes. In addition to these 

State laws, Federal regulations prohibit 

drunk driving on Federal lands.124 An 

individual may not operate a motor 

vehicle on Federal land if they are 

unable to safely operate the vehicle due 

to the influence of alcohol or other 

drugs, or if their BAC is .08 g/dL or 

greater.125 The law also authorizes 

testing of three bodily fluids: blood, 

saliva, and urine. It includes 

stipulations around proper 

administration of accepted scientific 

methods and equipment used by 

certified personnel, noting that for blood 

sample testing, there are further 

restrictions whereby normally a search 

warrant is required from an authorized 

individual. 

b. Training and Best Practices for Law 

Enforcement, Prosecutors, Judges, and 

Other Public Safety and Criminal Justice 

Partners 

NHTSA actively supports efforts to 

develop training and best practices for 

law enforcement, prosecutors, judges, 

and other public safety and criminal 

justice partners regarding the detection, 

prosecution, and adjudication of drunk 

and impaired driving. A brief sampling 

of NHTSA’s work in this area includes 

the following: 

Development and application of field 

sobriety tests. In the mid-1970s NHTSA, 

with the cooperation and assistance of 

the law enforcement community, 

conducted research that resulted in a 

standardized battery of three field 

sobriety tests (the horizontal gaze 

nystagmus test; the walk-and-turn test; 

and the one-leg stand test). Police 

officers use these tests to help establish 

probable cause for a driving while 

intoxicated (DWI 126) arrest. 

Standards for alcohol breath-test 

devices. Evidential breath test devices 

conform to established specifications 

and can be used as evidence in court. 

NHTSA publishes standard 

specifications for evidential breath-test 

devices, and a ‘‘Conforming Products 

List’’ of alcohol testing and screening 


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127Federal Register/Vol. 58, No. 179/pp 48705– 

48710/Friday, September 17,1993/Notices (58 FR 

48705) Federal Register/Vol. 77, No. 115/pp 35745– 

35750/Thursday, June 14, 2012/Notices (77 FR 

35745, 77 FR 35747). 

128https://www.nhtsa.gov/sites/nhtsa.gov/files/ 

documents/12323_tsrpmanual_092216_v3-tag.pdf. 

129https://www.appa-net.org/idarc/trainingfaculty.html. 

130https://www.ncsl.org/research/transportation/ 

state-ignition-interlock-laws.aspx. 

131Evaluation of the New Mexico Ignition 

Interlock Program (2010). DOT HS 811 410. 

132Evaluation of State Ignition Interlock 

Programs: Interlock Use Analyses from 28 States, 

2006–2011 (2015) DOT HS 812 145. 

133Teoh, Eric R./Fell, James C./Scherer, Michael/ 

Wolfe, Danielle E.R., State alcohol ignition interlock 

laws and fatal crashes, Traffic Injury Prevention 

(TIP), October 2021. 

134Hedlund, J., & Fell, J. (1995). Persistent 

drinking drivers in the U.S., 39th Annual 

Proceedings of the Association for the 

Advancement of Automotive Medicine, October 16– 

18, 1995, Chicago, IL (pp. 1–12). Des Plaines, IL: 

Association for the Advancement of Automotive 

Medicine. 

135This research also considered impairment 

including drugs and drowsiness. 

136 78 FR 26849 (May 8, 2013), available at 

https://www.volpe.dot.gov/sites/volpe.dot.gov/files/ 

docs/Breath%20Alcohol%20Ignition%20

Interlock%20Device%20%28BAIID%29%20

Model%20Specifications.pdf. 

devices.127 Law enforcement officers 

use the totality of the evidence in 

determining whether sufficient probable 

cause exists to effectuate an arrest for 

drunk driving. This includes 

observation of the vehicle in motion, 

results of the standardized field sobriety 

tests, and other information to establish 

probable cause. An officer may use a 

preliminary or evidential breath test 

device to measure BrAC. A suspect may 

also be requested to provide a blood or 

urine sample. 

Arrest and crash reporting. NHTSA 

provides training on arrest and crash 

reporting to law enforcement so that the 

data collected during a traffic stop or 

arrest, or at the scene of a crash, is 

uniform, clear, and concise. 

Training curriculum development for 

law enforcement, prosecutors, judges, 

and other public safety and criminal 

justice partners. Through cooperative 

agreements and partnerships, NHTSA 

supports training for law enforcement, 

prosecutors, judges, and other public 

safety and criminal justice partners. 

For example, NHTSA provides 

(through a cooperative agreement with 

the International Association of Chiefs 

of Police) funding for curricula 

development and management of 

programs developed to train law 

enforcement in detecting, investigating, 

and apprehending impaired drivers. 

NHTSA also provides the law 

enforcement community with resources 

to carry out local DWI programs, such 

as supplying laminated pocket guides 

for the standard field sobriety tests to 

aid officers. Through partnerships with 

national law enforcement organizations 

such as the National Criminal Justice 

Training Center, NHTSA maintains a 

wide reach when providing these 

resources. 

NHTSA also helps ensure that 

organizations representing prosecutors, 

judges, and pretrial, parole, supervision, 

and probation officers have accurate and 

up-to-date information about the harm 

caused by impaired driving, the crash 

risk of various impairing substances, 

and evidence-based sanction and 

treatment options. For example, NHTSA 

has cooperative agreements with the 

National Traffic Law Center and the 

National Association of Prosecutor 

Coordinators to develop curricula and 

provide training to prosecutors working 

on impaired driving cases. Through 

these agreements, NHTSA provides 

prosecutors with information on 

relevant case law, monographs on 

various legal issues, an expert witness 

database, training courses, and peer-topeer support from Traffic Safety 

Resource Prosecutors (TSRP) in each 

State. The TSRP Program trains current 

and former prosecutors to become 

instructors for traffic crimes prosecutors 

and law enforcement personnel.128 This 

facilitates a coordinated, 

multidisciplinary approach to the 

prosecution of drunk and impaired 

driving. NHTSA also funds training 

through the National Judicial College on 

(among other things) evidence-based 

sentencing and supervision practices, 

toxicology, the use of ignition 

interlocks, and DWI Courts. NHTSA 

also funds the American Bar 

Association to conduct the Judicial 

Outreach Liaison program providing 

trial judges with current evidence-based 

practices, peer-to-peer judicial 

education, a liaison to the broader 

highway safety community. 

Based on these models, NHTSA is 

also piloting similar education programs 

for pretrial, probation, parole, and 

supervision professionals 129 and 

toxicologists. 

2. Prevention 

Prevention strategies reduce impaired 

driving by reducing use of impairing 

substances or preventing driving by 

people who have been drinking or using 

other drugs. There are a variety of 

prevention countermeasures. Below we 

discuss the main ones. 

a. Alcohol Ignition Interlocks 

One impaired driving prevention 

strategy is requiring the installation of 

alcohol ignition interlocks. Ignition 

interlocks are devices that measure the 

driver’s BrAC and prevent the vehicle 

from starting if it exceeds a pre-set level 

(usually .02 g/dL). Interlocks are highly 

effective in allowing vehicles to be 

started by sober drivers, but not by 

alcohol-impaired drivers. Alcohol 

ignition interlocks are typically used as 

a condition of probation for DWI 

offenders after their driver’s licenses 

have been reinstated. Forty-four States 

require the devices for repeat, highBAC, or all offenders.130

There is evidence that requiring 

interlocks for driving under the 

influence (DUI) offenders helps reduce 

recidivism. NHTSA evaluated the New 

Mexico Ignition Interlock program in 

2010 131 and found that alcohol-sensing 

technology in vehicles can be 

successfully deployed to protect the 

public from alcohol-impaired drivers 

and that recidivism rates can be reduced 

if penetration of these devices is 

sufficient. In 2015, NHTSA reported on 

interlock use in 28 States.132 This 2015 

report identified important program 

elements for States to achieve and 

sustain high interlock use rates 

including: strong interlock requirements 

and incentives coupled with effective 

penalties for non-compliance; strong 

program management involving 

monitoring, uniformity, coordination, 

and education; and data and resources 

to support program management and to 

evaluate changes in program design. 

A more recent study found that laws 

mandating alcohol ignition interlocks, 

especially those covering all offenders, 

are an effective alcohol-impaired 

driving countermeasure that reduces the 

number of alcohol-impaired drivers in 

fatal crashes.133

NHTSA has also conducted research, 

developed model specifications, and 

provided information and funding to 

improve State ignition interlock 

programs. NHTSA research on ignition 

interlocks dates back to early studies on 

the increased likelihood for DWI 

offenders to be involved in fatal crashes 

while intoxicated.134 Based on research 

that license suspension alone did not 

keep DWI offenders from driving, 

NHTSA conducted research into 

performance-based interlocks that could 

prevent a drunk driver from starting the 

vehicle.135 NHTSA also drafted and 

revised model specifications for 

interlock devices. These specifications 

have developed over time and are 

published in the Federal Register as 

guidelines for State interlock 

programs.136 NHTSA has published an 


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137https://www.nhtsa.gov/sites/nhtsa.gov/files/ 

documents/ignitioninterlocks_811883_112619.pdf. 

This is a toolkit for policymakers, highway safety 

professionals and advocates that brings together 

resources that explain and support the use of 

alcohol ignition interlocks, identifies issues faced 

by ignition interlock programs and includes 

information on the use of interlocks in each State 

and the District of Columbia. It is designed to 

advance the understanding of ignition interlock 

technology, improving its application as an 

effective strategy to save lives and prevent impaired 

driving injuries. 

138https://www.nhtsa.gov/sites/nhtsa.gov/files/ 

811262.pdf. 

139See, e.g., https://rosap.ntl.bts.gov/view/dot/ 

1909. 

140https://aiipaonline.org/. 

141Bingham CR, Shope JT, Parow JE, 

Raghunathan TE. Crash types: markers of increased 

risk of alcohol-involved crashes among teen drivers. 

J Stud Alcohol Drugs. 2009 Jul;70(4):528–35. doi: 

10.15288/jsad.2009.70.528. PMID: 19515292; 

PMCID: PMC2696293. 

142https://crashstats.nhtsa.dot.gov/Api/Public/ 

ViewPublication/813313. 

143See e.g., https://www.ghsa.org/resources/Peerto-Peer19. 144https://www.trafficsafetymarketing.gov/. 

ignition interlock toolkit,137 a program 

guide on key features for ignition 

interlock programs,138 and various case 

studies and evaluation reports.139

NHTSA continues to fund the 

Association of Ignition Interlock 

Program Administrators.140

As discussed later in greater detail, 

since 2008 NHTSA has participated in 

and helped fund a cooperative research 

program, known as DADSS, which is 

developing next-generation vehicle 

alcohol detection technologies. 

b. Designated Driver and Alternative 

Transportation Programs 

NHTSA also supports designated 

driver and alternative transportation 

programs as another avenue for 

preventing impaired driving. 

Designated driver programs encourage 

drinkers to include someone in their 

party who does not drink and will be 

able to provide a safe ride home. Some 

designated-driver programs provide 

incentives such as free soft drinks for 

designated drivers. Mass-media 

campaigns—such as the NHTSAsponsored Ad Council campaign 

‘‘Friends Don’t Let Friends Drive 

Drunk’’—seek to raise awareness and 

promote the use of these programs. 

Alternative transportation programs 

offer methods people can use to get to 

and from places where they drink 

without having to drive. This includes 

public transportation (such as subways 

and buses) as well as for-profit and 

nonprofit ‘‘safe rides.’’ For-profit safe 

rides include transportation network 

companies that are on-demand and may 

be accessed through a mobile 

application. Nonprofit safe-ride 

programs are free to patrons or charge 

minimal fees and often operate in 

specific regions or at specific times such 

as weekends and holidays when 

impaired crashes occur at higher rates. 

Several States fund alternative 

transportation as part of their impaired 

driving prevention efforts. 

c. Alcohol Sales and Service 

Regulations/Programs 

Another common strategy to prevent 

impaired driving are regulations and 

programs that target the point at which 

alcoholic beverages are sold. 

Responsible beverage service programs 

cover alcohol sales policies and 

practices that prevent or discourage 

restaurant or bar patrons from drinking 

excessively or from driving while 

impaired by alcohol. NHTSA supports 

server training programs to teach servers 

how to recognize the signs of 

intoxication, how to prevent intoxicated 

patrons from further drinking and from 

driving, as well as bar and restaurant 

management policies to reduce 

impaired driving. 

d. Underage Impaired Driving 

Prevention 

One particular focus of prevention 

strategies is preventing underage 

impaired driving. Teenagers drink and 

drive less often than adults but are more 

likely to crash when they do drink and 

drive.141 While many of the prevention 

strategies discussed above apply both to 

adults and teenagers, NHTSA supports 

several prevention strategies directed 

specifically to those under the age of 21. 

NHTSA publishes fact sheets,142

research, and funded program guides 143

on teen traffic safety and effective 

practices to reduce teen impaired 

driving. NHTSA also partners with 

youth advocacy organizations as well as 

primary and secondary education 

organizations to provide youth-focused 

impaired driving prevention education, 

messages, teacher resources, and 

educational materials for drivers of all 

ages. Furthermore, NHTSA partners 

with driver educators to teach teen and 

novice drivers about the dangers of 

impaired driving and to develop driver 

education standards. 

3. Communications Campaigns 

Public service messaging and 

coordinated enforcement are also 

important behavioral strategies. 

Communications campaigns inform the 

public of the dangers of impaired 

driving and promote positive social 

norms of not driving while impaired. 

NHTSA coordinates with States and 

other traffic safety stakeholders to 

educate the public about the impairing 

effects of alcohol and drugs and the 

dangers they pose to drivers of all ages. 

NHTSA produces a communications 

calendar annually with details about 

specific campaign and enforcement 

periods, holidays, and other notable 

events during which time there may be 

increased dissemination of campaign 

messages and coordinated law 

enforcement efforts at the State and 

local level. Campaign materials are 

made accessible to the public and 

stakeholders online at Traffic Safety 

Marketing (TSM).144 These 

communications efforts can be divided 

into two categories: high-visibility 

enforcement and social norming 

campaigns. 

a. High-Visibility Enforcement 

Campaigns 

High-visibility enforcement 

campaigns coordinate highly visible and 

proactive law enforcement activities 

with public service messages 

highlighting the dangers of impaired 

driving and the enhanced enforcement 

efforts. NHTSA runs two national highvisibility impaired driving campaigns 

each year—one in August, leading up to 

and including Labor Day weekend, and 

one in December, during the winter 

holiday period. High-visibility 

enforcement campaigns include 

national media segments that air on TV 

and radio as well as digital media in 

English and Spanish. Both campaigns 

include national paid media buys 

incorporating both an alcohol-impaired 

driving message (Drive Sober or Get 

Pulled Over) and a drug-impaired 

driving message (If You Feel Different, 

You Drive Different. Drive High, Get a 

DUI). These campaign assets are 

available at no cost for States, regions, 

and other stakeholders to download and 

use during applicable campaign periods. 

During each campaign timeframe, 

NHTSA encourages law enforcement 

and other State agencies to use the 

provided assets on social media. State 

leaders can also engage with the local 

news media to expand awareness of the 

campaigns and associated messages. 

Each campaign period comes with 

information on how to conduct Media 

Buys, and its reports on the number of 

impressions made. 

b. Social-Norming Campaigns 

Communications efforts are not 

limited to high-visibility enforcement 

campaigns but also continue throughout 

the year. For instance, NHTSA has 

public service announcement 

campaigns that rely on donated time 


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145https://www.samhsa.gov/sbirt. 

146https://rosap.ntl.bts.gov/view/dot/2055. 

147https://rosap.ntl.bts.gov/view/dot/2055. 

148The concentration of CO2 in the breath 

provides an indication of the degree of dilution of 

the alcohol concentration indicating the distance 

from the sensor the breath was exhaled to 

determine if the sample is from the driver. 

and space from various media outlets 

throughout the nation. The main 

message for alcohol-impaired driving is 

‘‘Buzzed Driving is Drunk Driving,’’ and 

the main message for drug-impaired 

driving is ‘‘If you Feel Different, You 

Drive Different.’’ NHTSA works with 

the Ad Council to produce campaign 

resources (TV, radio, digital, print, and 

outdoor advertising) and distributes 

them to organizations that donate time 

and space to support campaign 

messaging. 

4. Alcohol and Drug Treatment, 

Monitoring, and Control 

Treatment for substance use is 

another major strategy to address the 

behaviors leading to drunk and 

impaired driving. It is widely 

recognized that many DWI first 

offenders and most repeat offenders 

meet criteria for an alcohol use disorder 

and are likely to continue to drink and 

drive unless the underlying substance 

use disorder is addressed. DWI arrests 

provide an opportunity to identify 

offenders with alcohol use problems, 

and as part of a plea bargain or 

diversion program, refer them to 

treatment in addition to imposing 

sanctions. 

NHTSA endorses the use of the 

Substance Abuse and Mental Health 

Services Administration’s Screening, 

Brief Intervention and Referral to 

Treatment (SBIRT) approach. This is a 

comprehensive, integrated, public 

health approach to the delivery of early 

intervention and treatment services for 

persons with substance use disorders, as 

well as those who are at risk of 

developing these disorders.145 To help 

States use an SBIRT approach NHTSA 

funded the American Probation and 

Parole Association to develop the 

Impaired Driving Assessment. This tool 

provides a framework for screening 

impaired drivers, estimating their risk 

for future impaired driving, and 

assessing responsivity to intervention 

efforts, among other things. 

NHTSA also encourages States and 

jurisdictions to establish DWI courts. 

DWI courts are specialized, 

comprehensive programs providing 

treatment, supervision, and 

accountability for repeat DWI offenders. 

These courts follow the well-established 

drug court model and are usually aimed 

at drivers with prior DWI offenses or 

those with BACs of .15 g/dL or higher. 

In 2019, NHTSA entered into a 

cooperative agreement with the National 

Center for DWI Courts to develop the 10 

Guiding Principles for DWI Courts 

document, provide education and 

training for both new and existing DWI 

Courts, fund technology for the 

expansion of reach to underserved 

populations, and fund services (e.g., 

treatment) to high-risk/high-need 

offenders.146 There is evidence that DWI 

courts have greater success in changing 

driver behavior compared to traditional 

court processes and sanctions. A 2011 

evaluation by NHTSA of three Georgia 

DUI Courts found substantial reductions 

in recidivism for repeat DUI 

offenders.147

B. Vehicle-Based Countermeasures 

While the previous section discussed 

the various behavioral efforts that 

NHTSA has engaged in, NHTSA is 

conducting complementary research on 

vehicle safety technologies that have the 

potential to prevent or mitigate drunk 

and impaired driving. The behavioral 

campaigns and the vehicle-based 

countermeasures are part of NHTSA’s 

dynamic strategy to achieve zero 

fatalities related to driver impairment. 

1. Summary of Research on VehicleBased Countermeasures 

This section summarizes five major 

research efforts focused on vehicle 

safety technologies: (1) Driver Alcohol 

Detection System for Safety, (2) Driver 

Monitoring of Inattention and 

Impairment Using Vehicle Equipment, 

(3) NHTSA’s Request for Information, 

(4) Technology Scans, and (5) 

Additional ongoing research. 

a. Driver Alcohol Detection System for 

Safety 

NHTSA has been conducting research 

to understand ways to detect driver 

impairment. A major research program 

is DADSS. NHTSA began the DADSS 

Program in 2008 through a Cooperative 

Agreement between the Agency and the 

Automotive Coalition for Traffic Safety 

(ACTS) to develop non-invasive 

technology to prevent alcohol-impaired 

driving by measuring blood or breath 

alcohol accurately, precisely, and 

rapidly. Exploratory research in early 

phases of the program established the 

feasibility of two sensor approaches for 

in-vehicle use: breath- and touch-based. 

Since then, there have been significant 

advances in sensor hardware and 

software development, as the program 

works toward meeting high-performance 

standards required for passive, accurate, 

and reliable alcohol measurement. 

There are two technology approaches 

under development for DADSS, and 

both use infrared spectroscopy to 

measure a driver’s alcohol 

concentration. The DADSS touch sensor 

measures the BAC in the capillary blood 

in the dermis layer of the skin on the 

palmar side of a driver’s hand. A touch 

pad with an optical module could be 

integrated into an ignition switch or 

steering wheel. When the driver touches 

the steering wheel or ignition switch, a 

near infrared light shines into the 

driver’s skin. The portion of the near 

infrared light that is reflected back is 

collected by the touch pad. This light 

transmits information about the skin’s 

chemical properties, including the 

concentration of alcohol present. The 

DADSS breath sensor uses detectors that 

simultaneously measure the 

concentrations of alcohol and carbon 

dioxide (CO2) in a driver’s exhaled 

breath.148 The diluted breath is drawn 

into a measurement cavity where optical 

detectors measure the amount of 

infrared light absorbed by the alcohol 

and CO2. Using these measurements, the 

driver’s BrAC is calculated. 

It is worth emphasizing that the 

current DADSS breath sensor requires 

directed puff of breath toward the 

sensor and would therefore not be 

considered passive under BIL. The end 

design that the DADSS program is 

working toward is a breath sensor that 

will capture naturally exhaled breath to 

make the calculation and may be 

considered passive as required by the 

BIL. The goal is not to require the driver 

to actively blow or puff air or take other 

action to provide the requisite sample 

for the system to analyze. The DADSS 

touch sensor is being designed to be 

embedded in something that the driver 

must touch to operate the vehicle, for 

example, push-to-start button, the 

steering wheel, or the gear shift selector. 

Therefore, NHTSA tentatively 

determines that such a touch sensor 

could be considered passive. 

As part of the cooperative agreement 

with NHTSA, ACTS is planning to 

develop DADSS Reference Designs for 

the sensors that include schematics, 

specifications, minimum hardware 

requirements, and other documentation 

for the DADSS sensors so the 

technology can be licensed, and sensors 

manufactured. ACTS plans for open 

licensing of the sensors, which means 

the technology will be made available 

on the same terms to any automaker or 

supplier interested in installing the 

technology into their vehicles or 

products. The first DADSS Reference 

Design—a directed-breath, zerotolerance (BrAC >.02 g/dL) accessory 


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149https://dadss.org/news/updates/when-mightthe-dadss-technology-be-in-u-s-cars-and-trucks. 

150Brown, T.L., & Schwarz, C.W., Jasper, J.G., 

Lee, J.D., Marshall, D., Ahmad, O. (in press) ‘‘Driver 

Monitoring of Inattention and Impairment Using 

Vehicle Equipment (DrIIVE) Phase 2.’’ National 

Highway Traffic Safety Administration. 

151 85 FR 71987, available at https://

www.regulations.gov/docket/NHTSA-2020-0102. 

152While not a passive device, a fourth supplier, 

Evanostics, provided information on a table-top oral 

fluid testing device that it suggests can test for 

alcohol and 10 classes of drugs in 15 minutes. A 

second supplier, Impirica, provided information on 

a mobile (tablet and phone) based cognitive 

screening that is designed to evaluate real time 

driving impairment. 

system for limited deployment in fleet 

vehicles—was released for open 

licensing in December 2021. A second 

DADSS zero-tolerance touch system 

reference design intended for fleet 

vehicles is expected in 2024, according 

to ACTS. ACTS expects touch and 

breath sensor reference designs for 

private vehicles, capable of higher BAC 

measurements, in 2025.149 NHTSA is 

aware that these delivery dates may be 

affected by several factors including 

further research and development and 

continued supply-chain issues resulting 

from the COVID–19 pandemic. These 

dates do not include the time necessary 

for any manufacturer to consider and 

implement design changes necessary to 

integrate these systems into vehicles. 

b. Driver Monitoring of Inattention and 

Impairment Using Vehicle Equipment 

Another research initiative that 

NHTSA has conducted is a program 

with the University of Iowa National 

Advanced Driving Simulator called 

Driver Monitoring of Inattention and 

Impairment Using Vehicle Equipment 

(DrIIVE).150 The research program 

explored driver impairment through two 

separate tracks of research: (1) detection, 

and (2) mitigation. The main goal of the 

DrIIVE detection track was to develop 

and evaluate a system of vehicle-based 

algorithms to identify alcohol, 

drowsiness, and distraction impairment. 

Three impairment-detection algorithms, 

covering impairment from alcohol 

intoxication, drowsiness, and 

distraction, successfully detected 

matching impairment type (e.g., 

drowsiness algorithm identified drowsy 

drivers from a dataset of drowsy and 

non-drowsy drivers) but had mixed 

results when applied to crossimpairment datasets (e.g., drowsiness 

algorithm identifying drowsiness from a 

dataset of drowsy and distracted 

drivers). 

The alcohol intoxication algorithm 

adapted well to the distracted and 

drowsy datasets, assuming that there 

was no alcohol intoxication present in 

those datasets (participants in the nonalcohol condition were neither dosed 

with alcohol, nor was BAC measured). 

The distraction algorithm also worked 

moderately well when applied to a 

cross-impairment dataset, although it 

worked better with head pose 

incorporated as a driver-based sensor 

signal (e.g., head pose, body posture), as 

discussed further below. 

It is important to note that the DrIIVE 

projects have focused on vehicle-based 

sensor data; however, they have also 

incorporated driver-based sensor 

signals. Additionally, the researchers 

investigated the benefits of taking 

individual differences between drivers 

into account in the training and 

operation of an algorithm. Driver-based 

sensors provided an added benefit to the 

performance and generalization of the 

distraction-detection algorithm, while 

individualizing the algorithms for 

individuals provided an added benefit 

to a drowsiness algorithm and an 

alcohol-intoxication algorithm. NHTSA 

recognizes that there are substantive 

challenges in individualizing algorithms 

across the entire driving population. 

Overall, the algorithms showed good 

success rates at correctly identifying 

driver impairment (and the correct 

source). However, the results of these 

studies also showed an interesting 

finding in which, in rare instances, 

drowsy drivers were categorized as 

alcohol impaired (despite not being 

dosed with alcohol). NHTSA has plans 

to initiate follow on research to refine 

the algorithm with the aim of 

determining if alcohol impairment 

detection can be achieved with a higher 

degree of accuracy. NHTSA recognizes 

the importance of accuracy of alcoholimpaired driver detection so that nonimpaired drivers are not 

inconvenienced. 

The DrIIVE mitigation research 

demonstrated the potential short-term 

effectiveness of both haptic and 

auditory staged alerts (i.e., the ability to 

improve driving performance for a 

period of time after the drowsiness alert 

is provided). Results show that drowsy 

drivers who received mitigation alerts 

maintained better vehicle control and 

had fewer drowsy lane departures than 

drowsy drivers without this mitigation. 

Additionally, drowsy drivers with 

mitigation showed less variability in 

speed maintenance. Furthermore, the 

research suggested that staged alerts 

may be more effective than discrete 

alerts for very drowsy drivers. Finally, 

alert modality did not affect driving 

performance, nor did the alerts 

significantly lower self-reported 

drowsiness. NHTSA has ongoing 

warning mitigation research for 

intoxication. 

c. NHTSA’s November 12, 2020 Request 

for Information 

NHTSA also sought input from the 

public on impaired driving technologies 

through its November 12, 2020, NHTSA 

Request for Information (RFI).151 The 

notice requested information to inform 

NHTSA about the capabilities, 

limitations, and maturity of available 

technologies or those under advanced 

stages of development that target 

impaired driving. Specifically, it 

requested details about technologies 

that can detect degrees of driver 

impairment through a range of 

approaches including: (1) technologies 

that can monitor driver action, activity, 

behavior, or responses, such as vehicle 

movements during lane keeping, erratic 

control, or sudden maneuvers; (2) 

technologies that can directly monitor 

driver impairment (e.g., breath, touchbased detection through skin); (3) 

technologies that can monitor a driver’s 

physical characteristics, such as eye 

tracking or other measures of 

impairment; and (4) technologies or 

sensors that aim to achieve direct 

measurement of a driver’s physiological 

indicators that are already linked to 

forms of impaired driving (e.g., BAC 

level for alcohol-impaired driving). 

NHTSA received 12 responses to the 

request for information. The following 

provides a high-level summary of those 

responses. 

The Alliance for Automotive 

Innovation (Auto Innovators) noted that 

Driver State Monitoring and Driver 

Behavior Systems are promising 

technologies that, with continued 

development, have the potential to 

significantly reduce distracted and 

drowsy driving. The Auto Innovators 

also stated that they are ‘‘. . . unaware 

of existing research demonstrating the 

robust effectiveness of these systems in 

detecting alcohol impairment. . . .’’ The 

Auto Innovators further stated that 

‘‘Driver State Monitoring/Driver 

Behavior Systems’ ability to identify 

high-functioning individuals impaired 

by alcohol is unknown, but likely poor. 

Additional research is needed to 

understand the opportunities and 

limitations of these systems relative to 

individual alcohol impairment. Preoperation systems, including DADSS, 

are not so limited because they are 

designed to quantify a driver’s BAC.’’ 

Three automotive suppliers 152 of 

camera-based DMSs and occupant 

monitoring systems responded to the 

November 12, 2020, Request for 


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153Pollard, J.K., Nadler, E.D., & Melnik, G.A. (In 

Press). Review of Technology to Prevent Alcoholand Drug-Impaired Crashes (TOPIC): Update. 

National Highway Traffic Safety Administration. 

154SAE International, Standard J3016, 

‘‘Taxonomy and Definitions for Terms Related to 

On-Road Motor Vehicle Automated Driving 

Systems,’’ April 2021. 

155Prendez, D.M., Brown, J.L., Venkatraman, V., 

Textor, C., Parong, J., & Robinson, E. (in press). 

Assessment of Driver Monitoring Systems for 

Alcohol Impairment Detection and Level 2 

Automation. National Highway Traffic Safety 

Administration. 

Information. Veoneer, a worldwide 

supplier of automotive technology, 

reported that it launched its first 

camera-based DMS to the market in 

2020. Its technology uses a true eye gaze 

system that determines the directional 

attributes of where the eyes are focused. 

Seeing Machines Limited, a DMS 

supplier, described their technology as 

providing evidence for the ability to 

reliably detect both drowsiness and 

visual distraction. Sony Depthsensing 

Solutions, an in-cabin occupant 

monitoring systems provider, described 

their ability to recognize driver features 

such as eye open/close and body 

position. The information they gain 

through sensors is used ‘‘to extract 

higher level features such as 

drowsiness, microsleep, sleep, 

distraction (long and short) detection, 

emotion estimation or sudden sickness 

detection.’’ Veoneer and Seeing 

Machines both noted that detecting 

driver alcohol impairment is more 

challenging and requires more 

technology development and research. 

Sony Depthsensing Solutions did not 

comment on the ability to detect other 

forms of impairment (e.g., alcohol). 

Eyegaze Inc., an eye tracking technology 

supplier, suggested their product, with 

additional work, could provide a 

solution to monitor driver attention 

when housed in an automobile. 

Safety advocates generally provided 

support for vehicle safety technologies. 

The National Safety Council, a safety 

advocate group, stated their support for 

in-vehicle passive alcohol detection 

technology options and DMSs. The 

Advocates for Highway and Auto Safety, 

a roadway safety advocacy group, noted 

their support for vehicle safety 

technologies, including voicing support 

for crash avoidance technologies, 

expedited DADSS research and offender 

ignition interlocks, among other things. 

Mothers Against Drunk Driving (MADD) 

submitted two separate comment 

submissions to the docket, which 

included 241 examples of technology 

related to detection of alcohol in blood 

or breath, other indicators of alcohol 

intoxication, drug impairment, 

drowsiness, and driver distraction/ 

inattention. Finally, a submission by the 

American National Standards Institute, 

Inc, provided research references on eye 

tracking as an indicator of impairment. 

d. Technology Scans 

In addition to the aforementioned RFI, 

NHTSA contracted with two different 

groups to independently review the 

state of publicly available information 

related to impairment detection. The 

first is an update to the ‘‘Review of 

Technology to Prevent Alcohol- and 

Drug-Impaired Crashes (TOPIC)’’ 

report.153 This report updates the 2007 

evaluation of vehicular technology 

alternatives to detect driver BAC and 

alcohol-impaired driving. It includes 

additional findings related to the 

detection of impaired driving due to 

drugs other than alcohol, drowsiness, 

and distraction. This report reviews 

relevant literature and technologies and 

incorporates input from stakeholders 

and the public (i.e., information 

received from the RFI). The report finds 

that tissue spectroscopy technologies 

are more accurate in estimating BAC 

than other technologies available at this 

time. Although driver attention 

monitoring technologies are presently 

able to detect drowsy driving and 

distracted driving, none specifically 

able to detect alcohol- or drug-impaired 

driving were found to be commercially 

available. 

The second technology scan is 

‘‘Assessment of Driver Monitoring 

Systems for Alcohol Impairment 

Detection and Level 2 Automation.’’ The 

report presents a review of DMS for 

alcohol impairment detection. A total of 

331 systems were reviewed, more than 

280 of which met inclusion criteria and 

are included in the report. The study 

found that few technologies are 

commercially available for alcohol 

impairment detection; some were not 

designed for in-vehicle use, and others 

were identified based on patent 

applications rather than evidence of 

functional systems. The review focused 

on features that were explicitly 

mentioned or indicated on the 

manufacturers’ websites, patents, device 

manuals, publications, or reports. The 

review, which was completed in 

October 2022, noted that camera-based 

DMS have been in vehicles since 2018 

for monitoring driver inattention to the 

forward roadway for SAE Level 2 

driving automation systems,154 as well 

as other vehicle-based sensors such as 

lane position monitoring and steering 

wheel torque monitoring to measure 

driver engagement and performance. 

The DMS were reviewed with a focus 

on the applicability of each system to 

driver alcohol impairment detection. 

The systems were classified as 

physiology-based, tissue spectroscopybased, camera-based, vehicle 

kinematics-based, hybrid (i.e., two or 

more of the classification types), and 

patent-stage systems. A key focus was to 

review systems that are being developed 

with the potential to detect alcoholbased driving impairment, as well as 

systems that can precisely estimate 

BAC. 

Of the systems reviewed, no 

commercially available product was 

found to estimate the amount of alcohol 

or identify alcohol-based impairment in 

the driver during the driving task. 

Behavioral indicators investigated 

included eye glances, facial features, 

posture, and vehicle kinematic metrics. 

However, systems with these 

capabilities are currently at various 

stages of the research and development 

process. 

Based on industry stakeholder 

interviews and expert review of 

technology documentation, the 

researchers found that approaches that 

are furthest along in the development 

process are those which measure the 

presence and amount of alcohol in a 

person’s body using BrAC and tissue 

spectroscopy. Camera-based and most 

physiology-based DMS are still in stages 

of preliminary research and design for 

alcohol-based impairment detection in 

passenger vehicles. The efficacy of 

vehicle kinematic measures in 

identifying alcohol-based impairment is 

currently unknown. Finally, hybrid 

systems are promising in being able to 

discern between driver states due to the 

number of different measures used in 

making state determinations. 

e. NHTSA’s Driver Monitoring Research 

Plans 

In addition to state-of-the-art 

assessments on DMSs, NHTSA has 

conducted research on driver state 

monitoring used in conjunction with 

SAE Level 2 driving automation.155

While using Level 2 driving automation, 

drivers are expected to both monitor the 

environment and supervise vehicle 

automation which is simultaneously 

providing lateral and longitudinal 

support to the driver. Some systems do 

not require the driver to have their 

hands on the wheel, while others 

include advanced features like 

automated lane changes and point-topoint navigation. The research included 

a literature review, stakeholder 

interviews, and system assessments. 

Many, but not all, Level 2 driving 

automation systems monitor visual and 

physical driver indicators, using 

camera-based sensing systems. Useful 


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156 23 U.S.C. 163(a) states ‘‘The Secretary shall 

make a grant, in accordance with this section, to 

any State that has enacted and is enforcing a law 

that provides that any person with a blood alcohol 

concentration of 0.08 percent or greater . . .’’. 

157The Path to Safe Hands-Free Driving | GM 

Stories; Ford BlueCruise | Consumer Reports TopRated Active Driving Assistance System | Ford.com; 

Nissan ProPILOT Assist Technology | Nissan USA; 

Teammate Advanced Drive Backgrounder—Lexus 

USA Newsroom. 

158Prendez, D.M., Brown, J.L., Venkatraman, V., 

Textor, C., Parong, J., & Robinson, E. (in press). 

Assessment of Driver Monitoring Systems for 

Alcohol Impairment Detection and Level 2 

Automation. National Highway Traffic Safety 

Administration. 

159Brown, T.L., & Schwarz, C.W, Jasper, J.G., Lee, 

J.D., Marshall, D., Ahmad, O. (in press) ‘‘Driver 

Monitoring of Inattention and Impairment Using 

Vehicle Equipment (DrIIVE) Phase 2.’’ National 

Highway Traffic Safety Administration. 

measures of general driver visual 

attention include measures of eye/pupil 

movement (e.g., fixation duration), 

measures of glance location (e.g., eyes 

on/off road), and measures of glance 

spread and range (e.g., scan path). 

While NHTSA’s research on DMS for 

Level 2 driving automation systems has 

implications for DMS applied to 

detection of alcohol impairment with 

regard to technological feasibility, there 

are important differences between these 

two applications. The safety issues, 

indicators and measures of driver risk, 

consumer acceptance, and potential 

interventions may be different for Level 

2 driving automation than they are for 

alcohol impairment. For example, 

drivers who are impaired by alcohol 

may appear to be visually attentive as 

measured by eye gaze toward the 

forward roadway, so alternative 

measures will be important to achieve 

reliable detection of impairment. 

Additionally, while alerts may prompt 

inattentive drivers to return their 

attention to the road, alerts alone cannot 

remedy driver impairment from alcohol. 

Additionally, the use of Level 1 and 

higher driving automation itself may 

pose challenges for the detection of 

alcohol impairment. This is because 

some of the driving performance 

measures that may be indicative of 

alcohol impairment (e.g., instability of 

lane position and speed) cannot be used 

when the vehicle itself is controlling 

that portion of the dynamic driving task. 

NHTSA is currently conducting 

research examining distraction that does 

not specifically focus on drunk driving 

or metrics but might be helpful to 

consider if the agency pursues an 

approach that requires camera-based 

driver monitoring to detect drunk 

driving. 

2. Passive Detection Methods and 

Available Technologies 

The ‘‘advanced drunk and impaired 

driving prevention technology’’ under 

BIL prescribes three methods of passive 

detection—(1) passively monitor the 

performance of a driver of a motor 

vehicle to accurately identify whether 

that driver may be impaired; (2) 

passively and accurately detect whether 

the blood alcohol concentration of a 

driver of a motor vehicle is equal to or 

greater than the blood alcohol 

concentration described in section 

163(a) of title 23, United States Code; 156

or (3) a combination of the first and 

second options. 

NHTSA interprets the first option as 

passively monitoring the driver’s 

performance (e.g., eyes on the forward 

roadway; taking appropriate steering, 

braking, or accelerating action) to gain 

an accurate determination of whether 

the driver may be impaired. Since 

‘‘driver impairment’’ could include 

more than just alcohol-impairment, the 

collective states of driver impairment 

would constitute the largest real-world 

safety problem. NHTSA interprets the 

second option to require passive and 

accurate detection of BAC over a 

prescribed limit (which is currently .08 

g/dL). This would exclusively target a 

subset of driver impairment conditions 

(i.e., alcohol-impaired drivers) focused 

on BAC detection. Alcohol-impaired 

drivers constitute the largest fatal driver 

impairment type. The third option is a 

combination of both the first and 

second. The following subsections 

discuss each of these options. 

a. Passively Monitor the Performance of 

a Driver To Accurately Identify Whether 

That Driver May Be Impaired 

For the purposes of this section, the 

following driver impairments were 

considered: drowsiness, distraction, and 

drunk, in the order of increasing fatality 

counts in the United States. While 

drugged driving is another known driver 

impairment, the ability to explicitly 

detect drug-impaired drivers is 

currently limited. Some of the effects of 

drugged driving, however, may be 

similar to the effects of alcohol-impaired 

or distracted driving, and therefore it is 

possible that vehicle technologies 

designed to detect other forms of 

impairment may also have the ability to 

detect some drug-induced impairments 

as well. As stated in the introduction, 

NHTSA is considering prioritizing 

alcohol impairment due to the 

significant safety problem caused by 

drivers intoxicated by alcohol and 

requests comment on whether that 

scope is most appropriate and whether 

its focus should be expanded to other 

types of impairment, including those 

discussed in this section. 

Driver performance generally consists 

of being attentive to the driving task, 

and taking appropriate vehicle control 

actions (i.e., steering, accelerating, and 

braking). Modern vehicles are equipped 

with many crash avoidance and driver 

assistance sensors that may provide 

opportunity to contribute to the 

detection of driver impairment. The 

following provides examples of those 

sensing technologies. 

Camera-Based Driver Monitoring 

Sensors: Camera-based DMSs are 

becoming more prevalent in vehicles 

with Level 2 driving automation 

features (i.e., adaptive cruise control 

and lane centering).157 NHTSA 

reviewed several available and 

prototype camera-based driving 

monitoring systems that publicly state 

the ability to monitor aspects of driver 

state, including driver’s eye gaze, 

eyelid/eye closure, pupil size, head/ 

neck position, posture, hand/foot 

position, and facial emotion during the 

driving task.158 The review found that 

most systems are currently available and 

intended for use in detecting driver 

drowsiness, inattention, and sudden 

sickness/non-responsive drivers and 

few are for specifically detecting 

alcohol-impairment. Although measures 

such as eye closure over time, pupil 

diameter, saccades (an eye movement 

between fixations), and fixations are 

parameters under study for detecting 

alcohol impairment, the review found 

that there was a lack of clinical and 

psychophysiological research to aid in 

specifically detecting driver alcohol 

impairment. The review found only 

three systems that claimed alcoholbased impairment detection as the 

objective, but the systems with these 

capabilities are not available on the 

market. 

It is notable, however, that other past 

NHTSA research suggested that the 

driver states of drowsiness and alcoholimpairment can present similarly to a 

driver monitoring system.159 So there 

may be an opportunity ‘‘to detect’’ some 

alcohol-impaired drivers that present as 

drowsy. However, as discussed further 

below, the countermeasure for 

‘‘prevention’’ applied to a sober drowsy 

driver, as opposed to an alcoholimpaired driver, may not be the same. 

For example, NHTSA contemplates and 

seeks comment on whether a sober 

drowsy driver may respond favorably to 

a warning and may even take a break 

from driving to recover, whereas an 

alcohol-impaired driver may not 

respond to a warning at all, or worse, 


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848 Federal Register / Vol. 89, No. 4 / Friday, January 5, 2024 / Proposed Rules 

160 Driver Monitoring | Alliance For Automotive 

Innovation (autosinnovate.org). 161https://www.nhtsa.gov/sites/nhtsa.gov/files/ 

808677.pdf. 162Harrison, E.L., & Fillmore, M.T. (2005). Are 

bad drivers more impaired by alcohol? Sober 

driving precision predicts impairment from alcohol 

in a simulated driving task. Accident Analysis & 

Prevention, 37(5):882–9. doi: 10.1016/ 

j.aap.2005.04.005; Lee JD, Fiorentino D, Reyes ML, 

Brown TL, Ahmad O, Fell J, Ward N, Dufour R. 

(2010). Assessing the Feasibility of Vehicle-Based 

Sensors to Detect Alcohol Impairment. National 

Highway Traffic Safety Administration. Report No. 

DOT HS 811–358; Calhoun, V.D. & Pearlson, G.D. 

(2012). A selective review of simulated driving 

studies: Combining naturalistic and hybrid 

paradigms, analysis approaches, and future 

directions. NeuroImage, 59(1), 22–35; Irwin C, 

Iudakhina E, Desbrow B, McCartney D. (2017). 

Effects of acute alcohol consumption on measures 

of simulated driving: A systematic review and metaanalysis. Accident Analysis & Prevention, 

(102),248–266. doi: 10.1016/j.aap.2017.03.001. 

Epub 2017 Mar 24. PMID: 28343124. 

163 Irwin C, Iudakhina E, Desbrow B, McCartney 

D. (2017). Effects of acute alcohol consumption on 

measures of simulated driving: A systematic review 

and meta-analysis. Accident Analysis & Prevention, 

(102)248–266. doi: 10.1016/j.aap.2017.03.001. Epub 

2017 Mar 24. PMID: 28343124. 

164 Das D., Zhou S., Lee J. D. (2012). 

Differentiating alcohol-induced driving behavior 

using steering wheel signals. IEEE Trans. Intel. 

Transp. Syst. 13 1355–1368. 10.1109/ 

TITS.2012.2188891. 

165 Kersloot, Tanita & Flint, Andrew & Parkes, 

Andrew. (2003). Steering Entropy as a Measure of 

Impairment. 

166https://www.nhtsa.gov/sites/nhtsa.gov/files/ 

808677.pdf 

167Prendez, D.M., Brown, J.L., Venkatraman, V., 

Textor, C., Parong, J., & Robinson, E. (in press). 

Assessment of Driver Monitoring Systems for 

Alcohol Impairment Detection and Level 2 

Automation. National Highway Traffic Safety 

Administration. 

168Prendez, D.M., Brown, J.L., Venkatraman, V., 

Textor, C., Parong, J., & Robinson, E. (in press). 

Assessment of Driver Monitoring Systems for 

Alcohol Impairment Detection and Level 2 

Automation. National Highway Traffic Safety 

Administration. 

169Prendez, D.M., Brown, J.L., Venkatraman, V., 

Textor, C., Parong, J., & Robinson, E. (in press). 

Assessment of Driver Monitoring Systems for 

Alcohol Impairment Detection and Level 2 

Automation. National Highway Traffic Safety 

Administration. 

170https://www.nhtsa.gov/equipment/driverassistance-technologies. 

171 Veldstra et al., 2012; Mets et al., 2011. 

172Rezaee-Zavareh et al., 2017; Lee et al., 2010; 

West et al., 1993; Irwin et al., 2017; Lenne et al., 

2010. 

173Arnedt et al., 2001; Yadav & Velaga, 2020; 

Irwin et al., 2017. 

174 Driver Attention Warning | Hyundai. 

respond in a negative way (e.g., 

becoming a more risky driver). 

Hands-On-Wheel Sensors: Drivers 

with their hands off the steering wheel 

for an extended period of time can be 

an indicator of driver inattention. 

Vehicles equipped with Level 2 features 

often have capacitive or steering torque 

sensors to confirm that the driver has at 

least one hand on the steering wheel. 

Capacitive sensing detects the change in 

capacitance of the steering wheel that 

results from the driver’s hands being 

removed from the wheel. Steering wheel 

torque sensing detects small steering 

inputs made by the driver. These 

sensors are commonly used in 

algorithms to encourage drivers to 

remain attentive during driving.160 It 

should be noted, however, that some 

Level 2 feature designs permit handsoff-wheel while supervising the vehicle 

automation. Current production 

vehicles with Level 2 features that 

permit drivers to remove their hands 

from the wheel have camera-based DMS 

that alert drivers if they look away from 

the forward roadway for more than a 

few seconds. 

Lane Departure and Steering Sensors: 

Poor precision as indicated by 

unintended lane excursions may 

indicate unsuitable driver states, 

including alcohol-based impairment.161

Alcohol reduces driving precision, and 

lane positioning is a key skill that is 

affected, even at low doses. Deviation of 

lane position from the lane center 

increases with increasing doses of 

alcohol.162 The Standard Deviation of 

Lane Position (SDLP) is considered a 

sensitive (but not specific) measure of 

alcohol impairment.163 Relatedly, 

measures of steering inputs can be used 

to detect alcohol impairment.164

Specifically, drivers who are impaired 

due to alcohol may exhibit more erratic 

driving patterns with tendencies to 

deviate from their lane position.165

The following crash avoidance sensor 

technologies equipped on modern 

vehicles could aid in detecting lane 

departure: forward-looking external 

cameras; steering wheel torque sensors; 

and blind spot detection sensors. 

When driven manually, forwardlooking external cameras commonly 

used in lane departure warning systems 

have the potential to identify a vehicle 

drifting out of its travel lane, typically 

when lane markings are present and 

observable (i.e., not snow-covered or 

worn). This could include drifting off 

the roadway or drifting into oncoming 

traffic. Tracking a vehicle’s lane 

departure warning activations over time 

could present as an indicator of a driver 

directing the vehicle to weave in and 

out of its travel lane (weaving and 

weaving across lanes are cues used by 

officers in detection of impaired 

driving).166 NHTSA’s research suggests 

that many vehicle manufacturers use 

lane position monitoring for detecting 

unintentional lane drift from several 

driver impairments—drowsiness and 

inattention.167 Some vehicle 

manufacturers were found to use lane 

position monitoring in available 

features, such as oncoming lane 

mitigation and run-off road 

mitigation.168

Some vehicles are equipped with 

steering wheel torque sensors that 

monitor a driver’s steering inputs. Such 

sensors could detect and monitor erratic 

steering corrections over time during the 

course of a trip. NHTSA’s research 

suggests that some vehicle 

manufacturers use steering input 

monitoring for detecting inattention, 

drowsiness, or sudden sickness/nonresponsive driver for vehicles equipped 

with Level 2 systems (used in an active 

emergency stop assist application).169

Many modern vehicles also come 

with blind spot warning sensors on the 

sides of the vehicle that can identify a 

vehicle in an adjacent lane.170 If an 

impaired driver attempts to steer into an 

adjacent lane of travel when another 

vehicle is in its blind spot, a vehicle 

equipped with this technology can warn 

the driver, or in some vehicles, even 

intervene via active blind spot 

intervention technology. 

Speed/Braking Sensors: Speed 

maintenance is generally affected by 

high BAC levels. NHTSA’s research has 

found that driver alcohol doses greater 

than BAC .05 g/dL can significantly 

impair an individual’s ability to 

maintain appropriate speed, particularly 

in complex environments.171 While 

some studies report increased speeds by 

alcohol-impaired drivers, others report 

speed decreases.172 The reduced ability 

to maintain consistent speed is referred 

to as the Standard Deviation of Speed 

Deviation (SDPD), which is commonly 

used to measure relative performance of 

impaired drivers compared to control 

groups. While findings concerning 

speed directionality (i.e., increase or 

decrease) are mixed, studies have 

consistently shown that speed deviation 

from posted speed limits tends to 

increase in alcohol-impaired driver 

groups.173

That said, some forward-looking 

external cameras can detect and 

interpret posted speed limit signs, 

which could provide an indicator of 

speeding when compared to the actual 

speed the vehicle is traveling. Some 

vehicles have telematics and maps that 

provide posted speed limit information. 

Vehicles also have brake sensors that 

could be monitored over time to sense 

repeated incidences of hard braking 

during a trip. 

Time-Based Sensors: Two other 

vehicle sensors that could be used in an 

overall driver impairment algorithm 

include duration of trip, and time of 

day. Monitoring the trip duration is 

used in some vehicle algorithms to warn 

about drowsy driving.174 After a certain 


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175Traffic Safety Facts 2020: A Compilation of 

Motor Vehicle Crash Data (dot.gov) Table 31. 

176Prendez, D.M., Brown, J.L., Venkatraman, V., 

Textor, C., Parong, J., & Robinson, E. (in press). 

Assessment of Driver Monitoring Systems for 

Alcohol Impairment Detection and Level 2 

Automation. National Highway Traffic Safety 

Administration. 

177Prendez, D.M., Brown, J.L., Venkatraman, V., 

Textor, C., Parong, J., & Robinson, E. (in press). 

Assessment of Driver Monitoring Systems for 

Alcohol Impairment Detection and Level 2 

Automation. National Highway Traffic Safety 

Administration. 

178A GM onboard experimental alcohol and drug 

impairment detection device of the 1970s | 

Hemmings 

179Prendez, D.M., Brown, J.L., Venkatraman, V., 

Textor, C., Parong, J., & Robinson, E. (in press). 

Assessment of Driver Monitoring Systems for 

Alcohol Impairment Detection and Level 2 

Automation. National Highway Traffic Safety 

Administration. 

180Toyota creating alcohol detection system 

(nbcnews.com). 

181Nissan Is Ahead of Its Time in Developing 

Anti-Drunk Driving Technology Over a Decade 

Before Potential Federal Mandate | GetJerry.com. 

182Tier 1 suppliers are companies that are direct 

suppliers to Original Equipment Manufacturers 

(OEM). 

183https://www.businesswire.com/news/home/ 

20180103005023/en/2018-CES-Hyundai-MobisAnnounces-Lifesaving-Autonomous-VehicleTechnology-to-Potentially-Eliminate-DrowsyDriving-Fatalities, last accessed July 7, 2023. 

184https://www.media.volvocars.com/global/engb/media/pressreleases/250015/volvo-cars-todeploy-in-car-cameras-and-intervention-againstintoxic. 

length of time, a vehicle may provide an 

icon (e.g., a coffee cup-like symbol) on 

the instrument panel to suggest a driver 

take a break from the driving task. 

Monitoring the trip duration may also 

help in identifying repeated lane 

departures over time. Monitoring the 

time of day could be added to other 

detection methods to help confirm 

detection of drowsiness or alcoholimpairment states at late night times. 

Most alcohol-impaired driving fatalities 

in the United States occur between 6 

p.m. and 3 a.m.175

Physiological Sensors: There are also 

a variety of physiological-based systems 

under research that use biometric 

measures from the driver to infer driver 

state. These could include heart rate, 

sweat, and blood pressure, among 

others. NHTSA’s research found that 

many were in the research and 

development stage, including those for 

breath alcohol detection (which will be 

discussed in the next section).176 A 

practical limitation of their use may be 

the fact that detecting driver impairment 

may be reliant upon background 

knowledge of a specific driver’s baseline 

physiological characteristics (to sense 

elevated levels) and can be attributable 

to multiple physiological states (e.g., 

stress). 

In summary, NHTSA’s research 

suggests that many driver impairment 

detection strategies use different 

combinations of measures, but the 

available documentation of multidetection approaches is rare, and when 

present, details of the underlying 

algorithms are sparse.177 It is reasonable 

to assume that the combination of more 

sensors and driver metrics will improve 

the confidence in driver state inference. 

Little data is available, however, to 

inform NHTSA on which combination 

of sensors and indicators of driver state, 

if any, would achieve greater accuracy 

and reliability of impairment detection. 

Vehicle manufacturers have 

announced concept vehicles or 

production plans for active/passive 

technologies to mitigate alcoholimpaired driving for many years. For 

example, a media article 178 cited 

alcohol-impaired driver research by 

General Motors dating back to the 1970s 

on a critical tracking test (CTT) 

‘‘experimental deterrent’’ that used the 

result from a 10-second test the driver 

took each time he or she got behind the 

wheel to determine whether the car 

would start. Tests were reported to use 

driver steering wheel movement and a 

gauge on the instrument panel where 

the driver would have to keep the 

needle on the gauge in the acceptable 

range through a series of progressive 

needle movements. Another concept 

involved cognitive tests where a series 

of five numbers appeared above five 

numbered white buttons on the 

instrument panel (or on a keypad). To 

pass the test, the driver must replicate 

the number sequence by using buttons 

and complete it in a designated 

timeframe. 

More recently, a 2016 patent held by 

General Motors, ‘‘Method and System 

for Mitigating the Effects of an Impaired 

Driver,’’ aims to detect inattention and 

alcohol-based impairment through use 

of camera-based detection measures 

(i.e., eye gaze, eyelid/eye closure, and 

facial/emotional measures), as well as 

lane monitoring and steering input.179

Similarly, in 2007, Toyota announced 

its intent to create a fail-safe system for 

cars that detects drunk drivers and 

automatically shuts the vehicle down if 

sensors pick up signs of excessive 

alcohol consumption. According to a 

media report,180 cars fitted with the 

detection system will not start if sweat 

sensors in the driving wheel detect high 

levels of alcohol. The system could also 

detect abnormal steering, or if a special 

camera shows that the driver’s pupils 

are not in focus, the car would be 

slowed to a halt. Toyota had reportedly 

hoped to fit cars with the system by the 

end of 2009. NHTSA does not know the 

current status of this Toyota technology 

and seeks comment on its effectiveness 

and availability. 

During the same timeframe, Nissan 

also reportedly developed a concept car 

with technology to detect alcohol in the 

breath and sweat of the driver.181

Nissan’s concept car had an alcohol 

sensor in the transmission shift knob, 

and in the driver’s and passenger’s 

seats. Both reportedly worked together 

to detect traces of alcohol in the cabin 

past a certain threshold. If the driver’s 

seat or shift knob had detected any 

alcohol while still parked, the 

transmission locked and made the car 

immobile. A second feature was a facial 

monitoring system built to monitor 

signs of drowsiness or distraction by 

monitoring the driver blinking rate. 

Once detected, a voice message alert 

was issued, and the seat belt was 

tightened to gain the attention of the 

driver. A third concept that was further 

developed after the 2007 timeframe was 

a road monitoring system. Nissan put 

technology in vehicles that monitored 

lanes and alerted drivers when the 

vehicle drifted out of the current lane, 

which Nissan reportedly believed 

mitigated safety risks associated with 

distracted driving. 

Hyundai Mobis, a global Tier 1 182

supplier, has been researching a 

technology called DDREM—Departed 

Driver Rescue and Exit Maneuver. 

Initially announced at the Consumer 

Electronics Show in 2018,183 DDREM 

uses an infrared camera to capture 

driver facial and eye movements to 

determine if the driver keeps eyes 

forward, changes blinking patterns, or 

exhibits other signs of drowsiness. The 

technology also looks for key identifiers 

used in advanced driver assistance 

systems (e.g., if the driver is moving in 

and out of a lane, crossing lanes, zig 

zagging, or making erratic movements). 

On March 20, 2019, Volvo Cars 

announced plans to deploy in-car 

cameras and intervention against 

intoxication and distraction.184 Its press 

release stated, ‘‘Volvo Cars believes 

intoxication and distraction should be 

addressed by installing in-car cameras 

and other sensors that monitor the 

driver and allow the car to intervene if 

a clearly intoxicated or distracted driver 

does not respond to warning signals and 

is risking an accident involving serious 

injury or death.’’ The press release 

provided examples of behaviors to be 

detected: a complete lack of steering 

input for extended periods of time, 

drivers who are detected to have their 

eyes closed or off the road for extended 


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185 2024 Volvo EX90 Full Electric 7 Seater SUV 

| Volvo Car USA (volvocars.com) According to its 

website, the vehicle’s ‘‘Pilot Assistance’’ feature 

‘‘can help keep an eye on the traffic and lane 

markings and support you by adapting your speed 

and distances given the current driving conditions. 

It can provide speed control in steep curves and 

steering support while changing lanes. If the car 

detects any sign of the driver being unresponsive, 

it can brake the vehicle to a standstill within the 

lane.’’ 

186https://www.consumerreports.org/car-safety/ 

driver-monitoring-can-pull-car-over-if-driverincapacitated-a1204997865/ ‘‘Some Volkswagen 

Arteon sedans sold in Europe and equipped with 

the Emergency Assist 2.0 feature will turn on their 

flashers and pull over to the side of the road if a 

driver becomes unresponsive. According to the 

automaker, if the car senses that a driver is not 

using the accelerator, brake, or steering wheel, it 

will first try to awaken a driver by sounding alarms 

and tapping the brakes to ‘‘jolt’’ the driver into 

awareness. If the driver still doesn’t respond, it will 

automatically steer itself to the lane furthest from 

traffic on a multilane road and bring the vehicle to 

a stop. In Japan, Mazda has said it will debut its 

Co-Pilot system on new vehicles this year. Tamara 

Mlynarczyk, a Mazda spokesperson, tells CR that 

the system is ‘‘continuously monitoring’’ the 

driver’s performance. ‘‘In a potential emergency 

situation where the driver loses consciousness, the 

system is prepared to intervene and assist the driver 

or pull the car over to a safer location,’’ she says. 

On a multilane road, it may be able to pull the 

vehicle to the road’s shoulder.’’ 

187 2020 Data: Alcohol-Impaired Driving 

(dot.gov). 

188A false positive could occur when the system 

indicates a person is at the detection level for 

impairment, when they are not impaired. 

periods of time, as well as extreme 

weaving across lanes or excessively 

slow reaction times. It further stated 

introduction of the cameras on all Volvo 

models will start on the next generation 

of Volvo’s scalable SPA2 vehicle 

platform in the early 2020s. 

Most recently, Volvo introduced the 

model year 2024 Volvo EX 90 that has 

a ‘‘Driver Understanding System,’’ 

which uses two interior sensors and a 

capacitive steering wheel along with the 

vehicle’s exterior sensors to understand 

if a driver is distracted or drowsy and 

when the vehicle may need to step in 

and support.185

Given the advancements in driver 

impairment detection (i.e., due to use in 

combination with SAE Level 2 driving 

automation technology), it is expected 

that other approaches will improve over 

time as strategies for mitigating 

inattention, incapacitation, drowsiness, 

and alcohol-impairment detection 

evolve—both from a technology 

perspective and a consumer acceptance 

stance. For example, Consumer Reports 

published an article suggesting that 

early versions of these driver 

impairment technologies are already 

appearing on cars in other countries.186

NHTSA seeks comment on the current 

state of technology and its effectiveness 

in passively detecting driver 

impairment. 

Questions on Technologies That 

Passively Monitor the Performance of a 

Driver To Accurately Detect Whether 

That Driver May Be Impaired 

1.1. NHTSA requests feedback on the 

two technology scan findings. Are there 

technologies, or technology capabilities 

or limitations not captured in these 

reports? If so, what are they? 

1.2. NHTSA is concerned that 

behaviors consistent with drunk 

driving, like repeated potential lane 

departure and erratic speeding/braking, 

would be masked by an engaged SAE 

Level 2 driving automation systems. 

Would there be enough information 

from other sensors (e.g., camera-based 

DMS, hands-on-wheel detection) to 

detect driver impairment and driver 

impairment type when SAE Level 1 or 

2 driving automation systems are 

active? 187

1.3. NHTSA is concerned about the 

limitations of vehicle sensor-based 

impairment detection systems to operate 

fully when certain sensors are impeded. 

External circumstances may include 

common roadway conditions such as 

darkness, heavy weather, roads with 

poor markings, or unpaved roads. 

Circumstances within the vehicle may 

include driver accessories, such as 

infrared light-blocking sunglasses, 

masks, or hats that may obscure the 

view of the driver to a DMS camera. If 

one or more sensors are impeded by 

such conditions, is there enough 

information from other sensors to detect 

driver impairment? Does this vary by 

impairment type? What are the 

operational limitations of such systems? 

1.4. NHTSA is seeking input on how 

a test procedure for driver impairment 

detection systems could be developed 

and executed in a FMVSS. For example, 

does the test need to be conducted in a 

moving vehicle to capture lane drift or 

weaving? If so, what are potential 

testing approaches or procedures? Are 

humans required for camera-based DMS 

assessment? Are there particular 

accessories (e.g., sunglass types, facial 

coverings) that would be required for 

testing? Is it feasible to conduct testing 

in darkness? What type of accuracy 

could be attained? How might this vary 

based on intended impairment type 

detection? 

1.5. What kind of performance 

requirement should NHTSA consider to 

mitigate defeat strategies (e.g., taping 

over the camera-based DMS or 

removing/replacing rear-view mirrors 

that contain driver monitoring 

equipment)? 

1.6. What metrics and thresholds (e.g., 

eye gaze, lane departure violations, 

speed, blind spot warning triggers, lane 

position variability, speed variability), 

or combination thereof, are most 

effective at measuring driver 

impairment? These would include timebased parameters from the start of the 

ignition cycle and those used for 

continuous monitoring. How feasible is 

it to implement these metrics in 

passenger vehicles? Should these vary 

by impairment type? Might these 

measures conflict across impairment 

types? Should NHTSA require 

impairment detection systems be able to 

collect specific metrics? Why or why 

not? 

1.7. NHTSA seeks comment on 

whether it should be necessary for an 

impairment detection system to 

determine what kind of impairment a 

driver has (e.g., drowsy, distracted, 

drunk) if the driver triggers certain 

metrics that indicate the driver is 

impaired by at least one of those 

impairments? For example, 

incapacitation, drowsiness, and 

distraction could be captured by 

camera-based monitoring systems, but 

they may also detect some alcoholimpaired drivers. 

1.8. Are there characteristics that 

would separate sober impairments from 

alcohol-induced impairments (e.g., 

horizontal gaze nystagmus or 

myokymia)? If so, what are they? Are 

there other non-alcohol induced 

conditions in which some of these 

characteristics might appear? If so, 

please provide examples. 

1.9. NHTSA seeks comment about 

whether certain conditions listed in the 

previous question (e.g., myokymia) 

might result in false positives 188 in 

certain situations (e.g., stress) or with 

certain populations (e.g., older drivers). 

1.10. What precision and accuracy 

should driver monitoring technology be 

required to meet for the purposes of 

detecting alcohol impairment? Under 

what conditions should these 

technologies be demonstrated to work? 

Are there driver characteristics, 

environmental conditions, or other 

factors that might limit the usefulness or 

applicability of certain technologies 

under certain conditions? Should there 

be a maximum time allowed for a 

system to develop a determination of 

impairment, after the indicators of 

impairment are detected? 

1.11. Under what conditions should a 

vehicle allow a driver to turn off driver 

impairment monitoring, if at all? If 


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189https://neurosciencenews.com/ai-alcoholvoice-22191/. 

190Lukas S.E., Ryan E., McNeil J., Shepherd J., 

Bingham L., Davis K., Ozdemir K., Dalal N., Pirooz 

K., Willis M., Zaouk A. 2019. Driver alcohol 

detection system for safety (DADSS)—human 

testing of two passive methods of detecting alcohol 

in tissue and breath compared to venous blood. 

Paper Number 19–0268. Proceedings of the 26th 

International Technical Conference on the 

Enhanced Safety of Vehicles. 

191The breath sensor is being designed to capture 

a driver’s naturally exhaled breath upon first 

entering the vehicle. 

192The touch sensor is being designed to be 

imbedded in something that the driver is required 

to touch to operate the vehicle such as the pushto-start button or the steering wheel rim. 

193When might the DADSS technology be in U.S. 

cars and trucks?—DADSS—Driver Alcohol 

Detection System. (last accessed 3/20/2023), 

available at https://dadss.org/news/updates/whenmight-the-dadss-technology-be-in-u-s-cars-andtrucks/. 

allowed, should a system be reset to 

‘‘on’’ upon the next ignition cycle? 

1.12. NHTSA is interested in data, 

studies, or information pertaining to the 

effectiveness of various sensors or 

algorithms in correctly detecting driver 

impairment (collectively, and 

individual impairments). NHTSA is 

seeking comment on which metrics, 

thresholds, sensors, and algorithms 

employed by existing DMS technology 

that could be used in an alcohol 

impairment detection system could be 

sufficiently robust to meet the 

requirement that an FMVSS be 

objective. 

1.13. Are there other innovative 

technologies, such as impaired-voice 

recognition,189 that could be used to 

detect driver impairment at start-up? If 

so, how might these function passively 

without inconveniencing unimpaired 

drivers? How mature and accurate are 

these technologies? 

1.14. What level of sensitivity and 

specificity is necessary to ensure the 

DMS technology does not unduly 

burden unimpaired drivers or prevent 

unimpaired drivers from driving? Are 

there any DMS available on the market 

capable of detecting alcohol impairment 

with the level of sensitivity and 

specificity necessary to ensure this? 

1.15. How can developers of DMS 

technology ensure that people with 

disabilities are not disproportionately 

impacted? Specifically, how can the 

technology accurately account for facial/ 

body differences, chronic health 

conditions, and adaptive driving 

technologies? 

1.16. How repeatable and reliable 

must these systems be? Is there societal 

acceptance of some potential false 

positives that could inconvenience 

sober drivers knowing that it would 

capture drunk drivers? If so, what 

countermeasure might best facilitate 

this? In considering a possible 

performance standard, what false 

positive rate would place too great a 

burden on unimpaired drivers? 

1.17. What can be done to mitigate 

physical destruction or misuse 

concerns? If mitigations exist, how 

might these mitigations impact the 

effectiveness of DMS monitoring driver 

impairment? 

1.18. NHTSA seeks to ensure fairness 

and equity in its programs and 

regulations. As NHTSA considers 

technologies that can passively detect 

impairment, some of which monitor 

facial features through camera-based 

systems or voice recognition, how can 

NHTSA, in the context of an FMVSS, 

best ensure these systems meet the 

needs of vehicle users of all genders, 

races and ethnicities, and those with 

disabilities? 

b. Passively and Accurately Detect 

Whether the Blood Alcohol 

Concentration of a Driver of a Motor 

Vehicle Is Equal to or Greater Than the 

Blood Alcohol Concentration Described 

in Section 163(a) of Title 23, United 

States Code 

The second option presented in BIL is 

one that requires the passive and 

accurate detection of a driver of a motor 

vehicle whose BAC is equal to or greater 

than the BAC described in Section 163 

(a) of title 23, United States Code. 

Section 163(a) of title 23 of the United 

States Code currently reads as follows: 

(a) General Authority.— 

The Secretary shall make a grant, in 

accordance with this section, to any 

State that has enacted and is enforcing 

a law that provides that any person with 

a blood alcohol concentration of 0.08 

percent or greater while operating a 

motor vehicle in the State shall be 

deemed to have committed a per se 

offense of driving while intoxicated (or 

an equivalent per se offense). 

Therefore, for this BIL option, a 

technology would need to passively and 

accurately detect whether the BAC of a 

driver of a motor vehicle is equal to or 

greater than .08 g/dL. Typically, BAC is 

measured as the weight of alcohol in a 

certain volume of blood (expressed in g/ 

dL). Accurate measurement of BAC 

typically requires a driver’s blood being 

drawn by a phlebotomist and sent to a 

lab where a medical laboratory scientist 

prepares samples and performs tests 

using machines known as analyzers. 

To measure BAC passively and 

accurately in a motor vehicle setting 

would therefore require alternative 

detection methods. The DADSS breathbased sensor, discussed above, can 

measure driver breath samples at the 

start of the trip or during the drive to 

measure driver BrAC. The DADSS 

touch-based sensor has the potential to 

be located on the ignition push-button 

or on the steering wheel. Similarly, it 

will be designed to take measurements 

at the start of the trip, or during the 

drive, in the case of the steering wheel 

application. 

Previous research through the DADSS 

program has established that the alcohol 

measurements from breath and touch 

sensors can be consistent, reproducible, 

and correlate well with traditional blood 

and breath alcohol measurements.190 As 

noted, the prototypes under 

development for a passive, accurate 

breath-based sensor 191 are planned for 

design completion in 2024 and a 

passive, accurate touch-based sensor 192

for 2025, with additional time needed to 

integrate systems in vehicle models and 

conduct verification and validation. 

Preliminary estimates suggest that 

manufacturers will need at least 18–24 

months to integrate the technology into 

vehicles.193

Therefore, a current limitation of this 

option is the fact that NHTSA is not 

aware of a passive and accurate .08 g/ 

dL BAC detection technology available 

for production vehicles today, and 

hence the timeframe for fleet 

implementation may be an issue. 

Questions on Technologies Aimed at 

Passively and Accurately Detecting 

Whether the BAC of a Driver of a Motor 

Vehicle Is Equal to or Greater Than .08 

g/dL 

2.1. In a follow-up to NHTSA’s 

technology scans, NHTSA seeks any 

new information on technologies that 

can passively and accurately detect 

whether the BAC of a motor vehicle 

driver is equal to or greater than .08 g/ 

dL. 

2.2. Although the legal thresholds for 

DUI/DWI laws focus on BAC/BrAC, 

BAC/BrAC are typically not used in 

isolation by law enforcement to 

determine impairment. BrAC/BAC may 

provide additional evidence of 

impairment after an officer has observed 

driving behavior, the appearance of the 

driver (e.g., face flushed, speech slurred, 

odor of alcoholic beverages on breath), 

the behavior of the driver, and any 

statements the driver has made about 

alcohol or drug use. Additionally, an 

officer may have administered the 

Standard Field Sobriety Test. 

Considering this, should regulatory 

options use BAC/BrAC in isolation to 

determine whether drivers are above the 

legal limit? If so, why? 


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852 Federal Register / Vol. 89, No. 4 / Friday, January 5, 2024 / Proposed Rules 

194Prendez, D.M., Brown, J.L., Venkatraman, V., 

Textor, C., Parong, J., & Robinson, E. (in press). 

Assessment of Driver Monitoring Systems for 

Alcohol Impairment Detection and Level 2 

Automation. National Highway Traffic Safety 

Administration. 

2.3. Are commenters concerned about 

using the legal limit (.08 g/dL) when 

there are indications that some 

individuals exhibit intoxication that 

would impact driving at lower or higher 

levels, depending on a number of factors 

discussed in the introduction? Why or 

why not? Might drivers with a BAC 

greater than 0 g/dL but less than .08 g/ 

dL interpret the fact that their vehicle 

allows them to drive as an indication 

that it is safe for them to drive after 

drinking? If so, are there ways to 

mitigate this possible unintended 

consequence? 

2.4. Given the quantifiable positive 

impacts on highway safety that Utah has 

experienced since lowering its BAC 

thresholds to .05 g/dL, should NHTSA 

consider setting a threshold lower than 

.08 g/dL? 

2.5. Is a BrAC detection that correlates 

to a BAC of .08 g/dL or above 

sufficiently accurate? 

2.6. Would a standard that allows or 

requires systems that approximate BAC 

using BrAC (at any concentration) meet 

the Safety Act’s requirement that 

standards be objective? Would the 

technology detect BAC? 

2.7. NHTSA is seeking input on how 

a .08 g/dL BAC detection test procedure 

could be developed and executed in a 

FMVSS. For example, are dosed humans 

required or would a test device to 

simulate human dosing be required? 

What type of accuracy could be 

attained? Would static test procedures 

accurately simulate dynamic 

performance? In a BrAC evaluation, how 

would variance in vehicle cabin volume 

be accounted for? 

2.8. What precision/accuracy should 

BAC detection technology be required to 

meet? Should any precision/accuracy 

requirement be fixed at a final rule 

stage, or should it become progressively 

more stringent over time with a phasein? 

2.9. For a BAC-based sensor, NHTSA 

seeks comment on when during a 

vehicle’s start-up sequence an 

impairment detection measurement 

should occur. For example, should an 

initial measurement of BAC/BrAC be 

required upon vehicle start-up, or before 

the vehicle is put into drive, and why? 

What is a reasonable amount of time for 

that reading to occur? 

2.10. NHTSA recognizes that ongoing 

detection would be necessary to identify 

if a driver reaches an impairment 

threshold only after commencing a trip, 

particularly if drinking during a drive. 

NHTSA seeks comment on whether 

BAC/BrAC measurements should be 

required on an ongoing basis once 

driving has commenced, and, if so, with 

what frequency, and why. Further, 

would a differentiation of the 

concentration threshold between initial 

and ongoing detection be recommended 

and why? 

2.11. NHTSA requests comments on 

operational difficulties in using touchbased sensing (e.g., consumer 

acceptance in colder climates when 

gloves may interfere) or in using breathbased sensing (e.g., mouthwash, vaping, 

alcohol-drenched clothing, or other false 

positive indicators). 

2.12. What can be done to mitigate 

physical destruction and misuse? 

Examples may include having a sober 

passenger press the touch sensor or 

breathe toward the breath sensor. If 

mitigations exist, how might these 

mitigations impact the effectiveness of 

alcohol detection systems? 

2.13. Are there cybersecurity threats 

related to impairment detection 

systems? If so, what are they? Are there 

potential vulnerabilities that might 

allow outside actors to interfere with 

vehicles’ impairment detection systems 

or gain unauthorized access to system 

data? How can cybersecurity threats be 

mitigated? Are there impairment 

detection methods or technologies that 

are less vulnerable than others? 

2.14. What temporal considerations 

should NHTSA include in any 

performance standards it develops (i.e., 

should NHTSA specify the amount of 

time a system needs to make a first 

detection upon startup before it will 

enable driving)? What amount of time is 

reasonable? 

c. A Combination Detection Approach: 

Passively Monitor the Performance of a 

Driver of a Motor Vehicle To Accurately 

Identify Whether That Driver May Be 

Impaired and Passively and Accurately 

Detect Whether the BAC of a Driver of 

a Motor Vehicle Is Equal to or Greater 

Than .08 g/dL 

This regulatory option combines the 

prior two. The combination of driver 

impairment detection (e.g., using 

camera-based driver monitoring and 

other vehicle sensors) and .08 g/dL BAC 

detection may provide more 

opportunity to capture alcohol-impaired 

drivers at the start of the trip as well as 

those that have elevated BAC during the 

drive. It further may have the potential 

to help mitigate false positive detections 

by providing multiple detection 

methods. 

In a NHTSA research study,194 all the 

reviewed hybrid systems used camerabased DMS measures in addition to 

vehicle kinematic or physiological 

measures. The study further suggested 

that augmentation of camera-based 

measures with other measures is 

expected to be a trend in driver state 

monitoring systems, particularly those 

that measure alcohol impairment. 

Specifically, NHTSA’s research study 

found sensors from two vehicle 

manufacturers, Toyota and Nissan, that 

used variables that have been found 

sensitive to alcohol impairment, 

including eye and eye closure measures, 

sweat, and BrAC. However, neither is on 

the market. 

Therefore, a current limitation of this 

option is the fact that NHTSA is not 

aware of a passive and accurate .08 g/ 

dL BAC detection technology available 

for production vehicles, as discussed in 

the previous section, and hence the 

timeframe for implementation may be a 

limiting factor. 

Questions on Technologies Aimed at a 

Combination of Driver Impairment and 

BAC Detection 

3.1. In light of the technology 

development needs to both passively 

and accurately detect .08 g/dL BAC and 

passively monitor the performance of a 

driver of a motor vehicle to accurately 

identify whether that driver may be 

impaired, are there interim strategies 

NHTSA should pursue? 

3.2. If an alcohol impairment 

detection system utilizes both BAC 

detection and DMS components, which 

DMS metrics best complement a BAC 

system to ensure accuracy, precision, 

and reliability? 

3.3. One possible benefit of a hybrid 

approach is that a camera system could 

help prevent intentional defeat of BAC/ 

BrAC sensors. For example, when a 

driver presses a touch sensor to measure 

BAC, a camera using machine vision 

could verify that it is the driver and not 

a passenger who touches the sensor. 

Could the camera provide additional 

benefits against defeating the system? 

3.4. NHTSA is considering a phased 

approach to addressing alcohol 

impairment. The agency is concerned 

about false positives. Effectively, this 

approach could have a first phase that 

aims to address alcohol-impaired 

drivers with a BAC of .15 g/dL or 

higher, where an alcohol sensor could 

have better accuracy in detecting 

alcohol-impairment, in combination 

with a camera-based DMS and/or other 

vehicle technologies. By improving the 

BAC detection accuracy, it may gain 

more consumer acceptance by lowering 

the false positive rate (i.e., the chance 

that someone with a BAC below .08 g/ 

dL is incorrectly identified as alcoholVerDate Sep<11>2014 18:20 Jan 04, 2024 Jkt 262001 PO 00000 Frm 00024 Fmt 4701 Sfmt 4702 E:\FR\FM\05JAP2.SGM 05JAP2

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195NHTSA notes that nothing in this document 

is intended to replace ignition interlocks used as a 

sanction for impaired driving offenses. 

impaired by a vehicle system). This 

would also target the drivers with the 

highest levels of impairment. With time 

and accuracy improvement, a second 

phase could be pursued to achieve the 

.08 g/dL BAC accuracy needed to 

comply with BIL. NHTSA therefore 

seeks comment on the viability of this 

regulatory approach. Is a BAC of .15 g/ 

dL the right limit to phase in? 

3.4. An option could also be a system 

with primary and secondary indicators 

within a driver impairment algorithm. 

For example, a system could incorporate 

a zero or low (.02 g/dL) tolerance BAC 

detection technology to initially sense 

whether alcohol is present in the 

vehicle. This would serve to ‘‘wake up’’ 

a driver impairment algorithm. Since 

this could be hand sanitizer or alcohol 

on a person’s clothing, a second 

confirmation of driver impairment from 

a driver monitoring system would be 

needed. Driver performance measures, 

such as eye gaze, lane weaving, etc. 

would be the primary indicators of 

impairment and utilize evidence of 

alcohol as a supplementary indicator for 

alcohol impairment. Given this 

approach, would such a system allow a 

vehicle to better distinguish between 

alcohol impairment and other forms of 

impairment that have similar indicators 

(i.e., the percentage of eyelid closure can 

be an indicator of both drowsy and 

drunk driving)? NHTSA notes that it has 

not identified any passive, productionready, alcohol-impaired driver detection 

technology capable of accurate detection 

at .02 g/dL and seeks comment on the 

status of such technology. 

3. Proposed Vehicle Interventions Once 

Driver Impairment or BAC Is Detected 

Once drunk driving or driver 

impairment is detected by a vehicle, the 

question becomes—what does the 

vehicle do with that information? BIL 

states that advanced drunk and 

impaired driving technologies include 

the ability to ‘‘prevent or limit’’ motor 

vehicle operation. There are a variety of 

strategies to prevent or limit operations 

that have been under research or have 

been implemented in production 

vehicles, such as the ignition interlocks 

discussed above.195 Others range from 

not allowing the vehicle to move out of 

park (transmission interlocks), to 

warnings (used perhaps as a supplement 

to an intervention approach), to slowing 

or stopping the vehicle (in lane, or on 

the shoulder or right-most lane). There 

are also many considerations involved 

in selecting appropriate interventions, 

given the timing of impairment 

detection (i.e., prior to the start of 

driving or during driving). Additionally, 

interventions appropriate for drunk 

driving may be different than those 

employed for other forms of driver 

impairment. For example, drunk drivers 

may respond more slowly to warnings 

than a sober but drowsy driver. 

Additionally, repeatedly warning a 

driver beyond the level or frequency 

that generates a positive reaction could 

lead to consumer annoyance and defeat 

efforts. NHTSA seeks to balance these 

concerns. 

a. Prohibiting Driving at Start of the Trip 

Ideally, once a defined level of 

alcohol has been accurately sensed from 

an impaired driver by vehicle 

technology, that individual would be 

prohibited from driving the vehicle. For 

example, this prohibition could be 

accomplished through an ignition or 

transmission shift interlock for an 

internal combustion engine vehicle. The 

vehicle could be put in accessory mode, 

and not able to move. Prohibiting an 

impaired driver from driving the vehicle 

at the start of a trip targets the largest 

number of alcohol-impaired fatalities. 

The .08 g/dL BAC touch-sensor and/ 

or breath-sensor detection technologies, 

which can ideally take immediate BAC 

measurements, are better suited for 

prohibiting driving at the start of the 

trip versus others that require a 

temporal measure of driver 

performance. While the technology 

readiness of the DADSS technologies to 

provide accurate .08 g/dL BAC detection 

is still undergoing research and 

development at this time, there are still 

many challenges associated with this 

prevention method that should be 

considered if it were to become a viable 

regulatory option. 

Assuming an accurate detection 

technology is fully developed (including 

a standardized method for testing), 

NHTSA would have to consider the 

overall effectiveness of the intervention 

strategy and the overall cost (economic, 

societal, etc.). Some considerations 

would, among other things, include: 

consumer acceptance; defeat strategies; 

unintended consequences of 

immobilizing a vehicle; need for an 

emergency override; and time between 

disablement and re-enablement. NHTSA 

is seeking feedback on the following 

questions. 

Questions on Prohibiting Driving at the 

Start of the Trip 

4.1. How would an alcohol-impaired 

person react to their vehicle not starting, 

and how can/should this be considered? 

Would some individuals decide to walk 

to their destination in the road, 

increasing their risk of being hit by 

another vehicle? Would they get a sober 

person to start their vehicle and then 

take over the driving task themselves? 

Are there countermeasures to 

discourage this practice by shutting 

down the vehicle for a period of time 

after two failed attempts? NHTSA seeks 

comment on potential research designs 

to develop better information in this 

area. 

4.2. What are the pros/cons of an 

ignition interlock as opposed to a 

transmission interlock prevention 

method for internal combustion engine 

vehicles? Is one superior to the other? 

Should both be acceptable compliance 

options if considered for an FMVSS? 

How would this differ for electric 

vehicles and what issues specific to 

electric vehicles should NHTSA 

consider? 

4.3. NHTSA seeks comment on any 

adverse consequences of an impaired 

driver being unable to drive his/her 

vehicle. For example, this could result 

in an alcohol-impaired person being 

stranded late at night for hours and 

susceptible to being a victim of crime or 

environmental conditions (e.g., 

weather). Or an alcohol-impaired 

camper may need to use his/her vehicle 

to escape from a rapidly approaching 

wildfire or environmental conditions 

(weather). How often would such 

incidences expect to occur (assuming 

full fleet implementation)? Are there 

logical strategies for mitigating the 

negative effects? What if the vehicle 

owner wishes to drive their vehicle on 

private land (i.e., not on public roads)? 

4.4. Given the previous examples, 

should there be an override feature for 

emergencies? Should the maximum 

speed of the vehicle be limited during 

override? How could an override feature 

be preserved for extreme situations and 

not used routinely when alcoholimpaired? 

4.5. If a system detects alcohol 

impairment prior to the start of a trip 

and an interlock is activated, should 

retest(s) be allowed, at what elapsed 

time interval(s), and why? NHTSA 

especially seeks comment on test/data 

analysis methods for determining an 

optimal retest interval strategy. Finally, 

should data be recorded on the vehicle 

if retesting is permitted? 

b. Vehicle Warnings Once Impairment 

Detected (On-Road) 

In addition to driver impairment 

being detected and prevented at the start 

of a trip, driver impairment can be 

monitored over time during the drive. 

Detecting that a driver is alcoholimpaired mid-trip is obviously a less 


lotter on DSK11XQN23PROD with PROPOSALS2
854 Federal Register / Vol. 89, No. 4 / Friday, January 5, 2024 / Proposed Rules 

196Hancock, P.A. (2017). Driven to distraction 

and back again. In Driver Distraction and 

Inattention (pp. 9–26). CRC Press. 

197https://www.forbes.com/wheels/advice/ 

automatic-emergency-stop-assistance/. 

198https://www.motortrend.com/news/volvodrunk-driving-distracted-cameras-sensors-safety/. 

199https://www.theverge.com/2019/3/20/ 

18274235/volvo-driver-monitoring-camera-drunkdistracted-driving. 

200https://www.volvocars.com/us/cars/ex90- 

electric/. 

desirable scenario (than detecting that a 

driver is impaired via an ignition/ 

transmission interlock) since an alcoholimpaired driver may have the 

unfortunate opportunity to get in a crash 

before the driver impairment is 

detected. However, this type of strategy 

may mitigate a larger group of driverimpairment fatalities, not just alcohol, 

and vehicle warnings could be relatively 

low cost. 

That said, there are many challenges 

associated with this intervention that 

should be addressed for it to become a 

viable regulatory option. Assuming an 

accurate detection technology was fully 

developed (including a standardized 

method for testing), NHTSA would have 

to consider the overall effectiveness of 

warnings as an intervention strategy 

against the various driver impairments, 

and the overall cost (e.g., economic, 

societal). Some of the considerations 

would, among other things, include: 

consumer acceptance, defeat strategies, 

unintended consequences of warnings, 

need for an incapacitation sensor, etc. 

NHTSA is seeking feedback on the 

following questions. 

Questions on Vehicle Warnings Once 

Impairment Is Detected 

5.1. NHTSA is aware of many vehicle 

manufacturers using visual/auditory 

warnings (e.g., a coffee cup icon) and 

encouraging drivers to take a break from 

the driving task. There are also visual/ 

auditory/haptic warnings to identify 

distracted driving or hands off the 

steering wheel while Level 2 driving 

automation systems are engaged. 

NHTSA is interested in any studies to 

support the effectiveness of these 

warnings, including designing against 

defeat strategies. NHTSA also seeks 

comment and studies on whether 

similar warnings may be effective for 

alcohol-impaired or incapacitated 

drivers or would additional 

interventions be needed. The system 

attributes that enhance a system’s 

effectiveness are of particular interest to 

NHTSA. Are there any unintended 

consequences from these warnings? If 

so, what are they? 

5.2. NHTSA’s research suggested that 

indicators of alcohol impairment are 

often also potential indicators of other 

conditions, such as drowsiness. Hence, 

the preventative measures of each 

condition may need to be addressed 

differently. For example, distracted 

drivers can quickly return their 

attention to the driving task, and drowsy 

drivers can recover with adequate rest 

as an intervention, but drunk drivers 

may need a much longer recovery time 

as alcohol metabolizes.196 NHTSA 

therefore requests research and 

information on what warning strategy 

would effectively encourage both 

drivers that are alcohol-impaired and 

drivers that have a different impairment 

to improve their performance in the 

driving task (e.g., by resting, getting a 

caffeinated beverage)? Or is there 

research to support that a warning 

would only be effective for a distracted 

driver or a drowsy driver, but may 

aggravate an alcohol-impaired driver? 

Are there other adverse consequences 

from using warnings to address multiple 

types of impairment? If so, what are 

they? 

5.3. NHTSA seeks comment on how 

manufacturers balance multiple alerts in 

response to different impairment 

detections. Given the many forms of 

impairment, if systems are developed 

that can distinguish effectively between 

alcohol impairment and other forms, is 

it practicable to employ a variety of 

different responses? Will multiple 

warnings (auditory, visual, or haptic) or 

other interventions for different forms of 

impairment only serve to confuse drunk 

drivers and lessen effectiveness for 

responses to drunk driving? 

5.4. NHTSA seeks comment on how 

warnings, especially multiple warnings, 

may impact drivers with an auditory or 

sensory processing disability. Would 

multiple warnings distract some 

drivers? 

5.5. NHTSA seeks comment on how 

systems react if the drowsy driver (or 

other inattentive or impaired driver) 

does not respond to warnings? What 

types of warning escalation strategies 

(timing, perceived urgency, and 

frequency) are used in industry and are 

they consistent among manufacturers? 

c. Vehicle Interventions Once 

Impairment Is Detected (On-Road) 

The most challenging countermeasure 

for preventing drunk and impaired 

driving fatalities is implementing 

vehicle interventions while the vehicle 

is in motion. There are a variety of 

strategies that have been under research, 

in development, or in production. Some 

are discussed below: 

Limp Home Mode—once impairment 

(or incapacitation) is detected, the 

vehicle speed is reduced to a lower 

speed for a given amount of time. 

Adaptive cruise control with a long 

following gap setting could be turned on 

to prevent a forward crash with other 

vehicles. Systems may provide the 

driver a warning that the driver needs 

to leave the highway. 

Stop in Lane—depending upon the 

vehicle manufacturer, the vehicle 

reduces speed and ultimately stops in 

the lane after a given time period of 

unresponsiveness of the driver 

(typically when the Level 2 driving 

automation system is engaged), putting 

on emergency flashers and unlocking 

the doors for easier entry into the 

vehicle. This presents a new hazard to 

motorists approaching the stopped 

vehicle, and a different kind of hazard 

for occupants of the stopped vehicle 

(i.e., the original hazard was the drunk 

driver, but now the hazard is potentially 

being hit by other motorists). Some SAE 

Level 2 driving automation systems 

make use of this feature if the driver 

becomes unresponsive and some also 

can call for assistance. 

Pull over to the Slow Lane (Right 

Lane) or Shoulder—some vehicle 

manufacturers have introduced more 

advanced concept or production 

vehicles that can pull over to the side 

of the road or into the ‘‘slow lane’’ once 

driver impairment (or incapacitation) is 

detected when Level 2 systems are 

engaged.197 This requires the vehicle to 

be equipped with lane-changing 

capability, where a vehicle needs to be 

able to understand whether there are 

vehicles or other road users in (or 

approaching) its blind spot in order to 

make a lane change. Modern vehicles 

increasingly have the technology to 

detect lane lines and blind spots, and to 

automate lane changes, under certain 

circumstances. 

For example, in 2019, media reports 

suggested a Volvo system would detect 

drunkenness, drowsiness, or 

distraction,198 and interventions could 

include limiting the speed of the vehicle 

or slowing it down and safely parking 

the car.199 The agency believes this 

Volvo system will not be available on 

production vehicles in the U.S. until 

2024.200 The agency will evaluate 

technologies as they become available. 

Questions on Vehicle Interventions 

Once Detected (On-Road) 

6.1. What types of vehicle 

interventions are in use today for SAE 

Level 2 driving automation systems 

when the system detects the driver is 

incapacitated? What prevents their use 


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201https://www.sae.org/standards/content/j3214_

202101/. 

202NHTSA’s New Car Assessment Program 

(NCAP) provides comparative information on the 

safety performance of new vehicles to assist 

customers with vehicle purchasing decisions and to 

encourage safety improvements. In addition to star 

ratings for crash protection and rollover resistance, 

the NCAP program recommends particular 

advanced driver assistance systems (ADAS) 

technologies and identifies the vehicles in the 

marketplace that offer the systems that pass NCAP 

performance test criteria for those systems. 

203https://cdn.euroncap.com/media/70315/euroncap-assessment-protocol-sa-safe-driving-v101.pdf. 

204https://cdn.euroncap.com/media/74468/euroncap-roadmap-vision-2030.pdf. 

205 87 FR 13452 (March 9, 2022), available at 

https://www.federalregister.gov/documents/2022/ 

03/09/2022-04894/new-car-assessment-program. 

206 Driver Monitoring Systems Can Help You Be 

Safer on the Road—Consumer Reports. 

207 IIHS creates safeguard ratings for partial 

automation. 

208U.S. Senator Ben Ray Luja ́n (2022) Luja ́n, 

Advocates Announce Technical Working Group to 

Implement Advanced Impaired Driving Prevention 

Technology. June 14, 2022. https://www.lujan.

senate.gov/newsroom/press-releases/ 

%EF%BF%BClujan-advocates-announce-technicalworking-group-to-implement-advanced-impaireddriving-prevention-technology/. 

209https://advocacy.consumerreports.org/ 

research/technical-working-group-on-advancedimpaired-driving-prevention-technology-viewsstatement-on-implementing-driver-impairmentprevention-technology/. 

in being coupled with driver 

impairment or BAC detection 

technology? What is the feasibility of 

using these interventions without 

engaging Level 2 driving automation? 

6.2. Stopping in the middle of the 

road could introduce new motor vehicle 

safety problems, including potential 

collisions with stopped vehicles and 

impaired drivers walking in the 

roadway. What strategies can be used to 

prevent these risks? How are risks 

different if the vehicle stops on the 

shoulder of the road? What preventative 

measures could be implemented for 

vehicles approaching the stopped 

vehicle? What are the risks to occupants 

involved in those scenarios? 

6.3. What is the minimum sensor and 

hardware technology that would be 

needed to pull over to a slower lane or 

a shoulder and the cost? 

Questions on Other Approaches To 

Reduce Impaired Driving 

7.1. As vehicle technologies continue 

to develop with potential to reduce 

impaired driving, what steps or 

approaches should NHTSA consider 

now, including potential partnerships 

with States or other entities? 

7.2. Which best practices have States 

found most effective in reducing 

impaired driving? Have States found 

approaches such as sharing information 

about drunk driving convictions to be 

helpful in reducing impaired driving? 

V. Summary of Other Efforts Related to 

Impaired Driving 

NHTSA is aware of several other 

ongoing efforts by external entities to 

establish performance requirements for 

systems to detect alcohol impairment or 

otherwise influence the development of 

such performance requirements. 

SAE International has developed SAE 

J3214, a ‘‘Breath-Based Alcohol 

Detection System’’ standard. This 

standard focuses on directed breath 

zero-tolerance systems, which are 

systems that look for any level of 

alcohol via the driver’s BrAC and 

require that a driver direct a breath 

toward a device for measurement. The 

standard was published on June 27, 

2021.201

The various New Car Assessment 

Programs (NCAPs) from around the 

world are also considering protocols for 

detection of driver state and system 

warning or intervention.202 Euro NCAP 

focuses on DMS and while its 

assessment protocol mentions impaired 

driving, the actual assessment focuses 

only on distraction, fatigue (i.e., 

drowsiness), and unresponsive 

drivers.203 Euro NCAP currently 

describes no specific assessment for 

alcohol impairment. Euro NCAP Vision 

2030 states that expanding the 

program’s scope of driver impairment 

by adding specific detection of driving 

under the influence is a priority for the 

mid-term: ‘‘. . . [A] key real-world 

priority for the midterm therefore is to 

expand the scope of driver impairment 

adding specific detection of driving 

under the influence and sudden 

sickness with advanced vision and/or 

biometric sensors and introducing more 

advanced requirements for risk 

mitigation functions.’’ 204 Mid-term is 

not defined in the text of the document, 

but a graphic indicates that 2032 is Euro 

NCAP’s targeted timeline. Even so, 

NHTSA is monitoring Euro NCAP’s 

efforts to see if they might be leveraged 

in this rulemaking activity. NHTSA’s 

understanding is that Australasian 

NCAP is considering protocols like Euro 

NCAP. Additionally, NHTSA has sought 

comment on the inclusion of DMS and 

alcohol detection systems in U.S. 

NCAP.205 NHTSA is in the process of 

considering all comments received and 

drafting a final decision that will 

establish a roadmap that includes plans 

to upgrade U.S. NCAP in phases over 

the next several years. Other 

organizations, like Consumer Reports 206

and the Insurance Institute for Highway 

Safety (IIHS),207 include DMS in their 

programs. Finally, NHTSA is aware of 

and following the work of the 

Impairment Technical Working Group 

that is intended to assist with the 

implementation of advanced impaired 

driving technology.208 The group is cochaired by members of the Johns 

Hopkins Center for Injury Research and 

Policy at the John Hopkins Bloomberg 

School of Public Health and MADD. The 

Impairment Technical Working Group 

formed with the goal of ‘‘identifying 

efficient and effective approaches for 

implementing driver impairment 

prevention technology in new cars.’’ 

The Impairment Technical Working 

Group is one of many groups or 

organizations interested in influencing 

this rulemaking proceeding. On April 

18, 2023, the Impairment Technical 

Working Group issued a short ‘‘Views 

Statement’’ that included three 

recommendations for implementing 

advanced impaired driving 

technology.209 These three 

recommendations are largely 

duplicative of the mandate in BIL but 

deviate slightly in that they explicitly 

request that multiple impairment types 

be included through this rulemaking 

(i.e., not limited to alcohol impairment). 

Also, the group’s three 

recommendations, when read together, 

describe the group’s preference for the 

third (i.e., hybrid) option in BIL. 

VI. Privacy and Security 

In considering next steps, NHTSA is 

aware of the need for comprehensive 

analysis of the privacy considerations 

that are relevant to developing 

performance requirements for systems 

that would identify and prevent 

individuals who are intoxicated from 

driving. Per the E-Government Act of 

2002 and internal DOT policies and 

procedures, NHTSA intends to conduct 

a privacy threshold analysis (PTA) to 

determine whether the agency should 

publish a draft Privacy Impact 

Assessment (PIA) concurrent with its 

issuance of a regulatory proposal that 

would establish performance 

requirements for advanced impaired 

driving technology. Although NHTSA 

welcomes privacy-related comments in 

response to this advance notice of 

proposed rulemaking, the agency 

expects that any future regulatory 

proposal and any accompanying draft 

PIA would provide the public with 

more detailed analysis necessary to 

evaluate potential privacy risks and 

proposed mitigation controls associated 

with advanced impaired driving 

technology. 

NHTSA also intends to consider 

closely any potential security 

implications that are relevant to 

developing performance requirements 


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210https://www.rollingstone.com/culture/culturenews/tiktok-drunk-driving-booze-cruise-gangalcohol-1234588210/. NHTSA would believe this 

trend was entirely edgy satire if it had not received 

correspondence that indicates that some genuinely 

believe they have a right to drive drunk. ‘‘Few 

would react the same to someone announcing they 

occasionally text while driving as they would to 

admitting to the occasional booze cruise while 

statistically there isn’t much difference in added 

danger.’’ NHTSA agrees that both texting while 

driving and driving while intoxicated are dangerous 

activities that put the safety of the public at risk. 

211NHTSA has said before that driving is a 

privilege, not a fundamental right. See https://

www.nhtsa.gov/open-letter-driving-public#:∼:text=

Driving%20is%20a%20privilege%2C

%20and,to%20protect%20all%20of%20us. 

Obeying the rules of the road is a prerequisite for 

the privilege of driving. See https://www.nhtsa.gov/ 

teen-driving/parents-hold-keys-safe-teen-driving. 

212Assertions that drunk driving is acceptable, or 

even a right, are not new. This 1984 opinion piece 

in the New York Times provides an example of 

someone who thought he was entitled to drive 

drunk, seemingly because he hadn’t killed or 

injured anyone yet. See https://jalopnik.com/checkout-this-pro-drunk-driving-op-ed-the-nyt-publishe1847408294; https://www.nytimes.com/1984/06/03/ 

nyregion/long-island-opinion-drinking-and-drivingcan-mix.html. Please visit the docket for a letter 

NHTSA received that appears to assert that some 

individuals should be permitted to drive drunk. 

213 Id. 

214https://jamanetwork.com/journals/jama

networkopen/fullarticle/2803962?utm_source=For_

The_Media&utm_medium=referral&utm_

campaign=ftm_links&utm_term=042023. 

for systems that would identify and 

prevent individuals who are intoxicated 

from driving. NHTSA requests 

comments on privacy and security 

issues that the agency should consider 

while developing its proposal. NHTSA 

acknowledges that many of the answers 

to these questions would be designspecific, and thus, expects that 

commenters might provide generalized 

input now with more specific input at 

the proposal stage. 

Questions About Privacy and Security 

Considerations 

8.1. NHTSA understands that 

personal privacy considerations are 

critical to the design of any system that 

monitors driver behavior or condition. 

Such considerations are also one 

component of consumer acceptance of 

systems described in this advance 

notice of proposed rulemaking. NHTSA 

seeks comment on privacy 

considerations related to use and 

potential storage of data by alcohol and 

impairment detection systems and how 

best to preserve driver and passenger 

personal privacy. Are there strategies or 

requirements (e.g., prohibitions on 

camera-based DMS from recording 

certain types of imagery) to protect 

privacy? 

8.2. Given the potential for different 

privacy impacts associated with 

different types of systems and 

information used in those systems, how 

should NHTSA weigh the different 

potential privacy impacts? For example, 

how should accuracy be weighed 

against privacy? Do certain metrics 

result in less privacy impact than others 

while providing the same or more 

accuracy? If so, how? 

8.3. What performance-based security 

controls should NHTSA consider 

including in its potential performance 

requirements for advanced impaired 

driving technology? Are there any 

industry or voluntary standards specific 

to these technologies that NHTSA 

should consider? If not, which 

standards do commenters believe would 

be most appropriate for these systems to 

comply with and why? 

8.4. Are there any additional security 

vulnerabilities that these systems would 

present that do not already exist in 

modern vehicles (e.g., passenger 

vehicles that are equipped with various 

technologies such as automatic 

emergency braking, lane keeping 

support, and others)? If so, what needs 

to be done to mitigate those potential 

vulnerabilities? 

8.5. What suggestions do commenters 

have regarding how the agency should 

go about educating the public about 

security and privacy aspects of 

advanced impairment and drunk 

driving detection technology? 

VII. Consumer Acceptance 

As discussed in the authority section 

of this document, consumer acceptance 

is one component of practicability that 

NHTSA must consider when developing 

a FMVSS. NHTSA is aware that a 

combination of misinformation related 

to advanced drunk and impaired driving 

technologies, and misbelief that there 

exists a right to drive while drunk 210

have resulted in some individuals 

believing that this rulemaking is 

pursuing a course of action that might 

unduly infringe upon their rights. 

NHTSA has received correspondence 

that leads the agency to believe that 

some individuals believe that they not 

only have a right to drive,211 but a right 

to drive while intoxicated by alcohol.212

As NHTSA has said before, driving is a 

privilege, not a right.213 These examples 

highlight potential consumer acceptance 

challenges, but not all such instances 

would be considered legitimate or 

sufficient to undermine the 

practicability prong of the Safety Act. 

Additionally, NHTSA is encouraged 

by the results of a recent study 

conducted by researchers with Johns 

Hopkins Bloomberg School of Public 

Health and published in the Journal of 

the American Medical Association 

Network Open.214 This study provides 

survey results from a relatively smallscale study with the objective of 

measuring public support for driver 

monitoring and lockout technologies. 

The survey contained two parts, one 

part querying whether participants 

supported or opposed ‘‘the recent action 

by Congress to require drunk driving 

prevention in all new vehicles.’’ The 

second part ask participants to indicate 

their level of agreement regarding six 

different warning or lockout 

technologies. A five-point scale was 

used for responses to both parts of the 

survey (strongly agree to strongly 

disagree). The primary findings of the 

study were that support for the 

congressional mandate on vehicle 

impairment detection technology was 

high, with 63.4 percent of respondents 

supporting the law (survey part 1.) For 

survey part 2, the author reported that 

64.9 percent of respondents either 

agreed or strongly agreed with the 

statement, ‘‘All new cars should have an 

automatic sensor to prevent the car from 

being driven by someone who is over 

the legal alcohol limit.’’ Results for 

neutral and negative responses were 

only reported in graphical form, not 

exact measurements (i.e., reported 

percentages and confidence intervals). 

Safety is the predominant 

consideration when evaluating potential 

vehicle performance requirements 

designed to combat drunk driving 

effectively. However, the public may not 

realize estimated associated benefits if 

vehicle performance requirements and 

the technologies that meet them are not 

designed to differentiate with precision 

drivers who are impaired from those 

who are not, minimize interventions to 

those necessary to achieve results, and 

conform with principles of human 

factors engineering and design. 

Question About Consumer Acceptance 

9.1. NHTSA requests comment on 

legitimate consumer acceptance issues 

related to advanced drunk and impaired 

driving technologies and suggestions for 

how the agency might be able to craft 

future proposed performance 

requirements to remedy any consumer 

acceptance issues. 

VIII. General Questions for the Public 

In the preceding preamble, NHTSA 

seeks comment on a variety of complex 

issues related to establishing a new 

FMVSS to require that passenger motor 

vehicles be equipped with advanced 

drunk and impaired driving prevention 

technology. These questions are 

numbered and included throughout the 

preamble text in the appropriate 

sections. But not all questions fit neatly 

under the preceding titles. As such, 


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215Telltale means an optical signal that, when 

illuminated, indicates the actuation of a device, a 

correct or improper functioning or condition, or a 

failure to function. 216 Indicator means a device that shows the 

magnitude of the physical characteristics that the 

instrument is designed to sense. 

NHTSA also seeks comment on the 

remaining questions listed below. 

10.1. NHTSA seeks comment on any 

reliability or durability considerations 

for alcohol impairment detection 

technology that may impact 

functionality over its useful life. 

10.2. NHTSA requests any 

information regarding the final installed 

costs, including maintenance costs, of 

impairment detection systems. 

10.3. Should NHTSA propose a 

standardized telltale 215 or indicator 216

(or set of telltales) indicating that 

impairment has been detected (and/or 

that vehicle systems have been limited 

in response)? Are there standardized 

industry telltales or indicators already 

developed for this sort of system that 

NHTSA should consider? 

10.4. NHTSA broadly seeks comment 

on how to best ensure that 

manufacturers have the flexibility to 

develop more effective impairment 

detection technology while preserving a 

minimum level of accuracy and 

reliability. 

10.5. Should NHTSA consider 

establishing a requirement that allows a 

vehicle’s BAC detection threshold to be 

adjusted downward based on the BAC 

thresholds of local jurisdictions or fleet 

owners? Note, this technology would 

not be intended or designed to replace 

a State’s enforcement of its own statutes. 

10.6. Earlier in this document, 

NHTSA noted that progress in reducing 

drunk driving resulting from many 

behavioral safety campaigns has 

plateaued. Should NHTSA devote more 

of its behavioral safety resources 

towards those programs and efforts that 

address underlying contributors to 

alcohol use disorder, including drunk 

driving, like mental health conditions? 

Are there effective behavioral safety 

campaigns or tactics NHTSA is not 

using? 

IX. Rulemaking Analyses 

A. Executive Order 12866, Executive 

Order 13563, Executive Order 14094, 

and DOT Regulatory Policies and 

Procedures 

The agency has considered the impact 

of this ANPRM under Executive Orders 

(E.O.) 12866, 13563, 14094 and the 

Department of Transportation’s 

regulatory policies and procedures. This 

action has been determined to be 

significant under E.O. 12866 (Regulatory 

Planning and Review), supplemented 

and reaffirmed by E.O. 13563 and 

amended by E.O. 14094, and DOT Order 

2100.6A, ‘‘Rulemaking and Guidance 

Procedures.’’ It has been reviewed by 

the Office of Management and Budget 

under E.O. 12866. E.O. 12866 and 13563 

require agencies to regulate in the ‘‘most 

cost-effective manner,’’ to make a 

‘‘reasoned determination that the 

benefits of the intended regulation 

justify its costs,’’ and to develop 

regulations that ‘‘impose the least 

burden on society.’’ Additionally, E.O. 

12866 and 13563 require agencies to 

provide a meaningful opportunity for 

public participation, and E.O. 14094 

affirms that regulatory actions should 

‘‘promote equitable and meaningful 

participation by a range of interested or 

affected parties, including underserved 

communities.’’ We have asked 

commenters to answer a variety of 

questions to elicit practical information 

about the approach that best meets these 

principles and the Safety Act and any 

relevant data or information that might 

help support a future proposal. 

B. Privacy Act 

Anyone can search the electronic 

form of all documents received into any 

of NHTSA’s dockets by the name of the 

individual submitting the document (or 

signing it, if submitted on behalf of an 

association, business, labor union, etc.). 

As described in the system of records 

notice DOT/ALL 14 (Federal Docket 

Management System), which can be 

reviewed at https://

www.transportation.gov/individuals/ 

privacy/privacy-act-systemrecordsnotices, the comments are searchable by 

the name of the submitter. 

C. Regulation Identifier Number (RIN) 

The Department of Transportation 

assigns a regulation identifier number 

(RIN) to each regulatory action listed in 

the Unified Agenda of Federal 

Regulations. The Regulatory Information 

Service Center publishes the Unified 

Agenda in April and October of each 

year. You may use the RIN contained in 

the heading at the beginning of this 

document to find this action in the 

Unified Agenda. 

Issued in Washington, DC, under authority 

delegated in 49 CFR 1.95 and 501.5. 

Ann Carlson, 

Acting Administrator. 

[FR Doc. 2023–27665 Filed 1–4–24; 8:45 am] 

BILLING CODE 4910–59–P 


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