U.S. Department of Transportation 1200 New Jersey Avenue SE., Washington, DC 20590

National Highway Traffic Safety Administration

TRAFFIC TECH

Technology Transfer Series

Number 393 September 2010

Research has indicated that per se laws for alcohol have been

effective in reducing alcohol-related fatalities. A difficulty

in prosecuting drivers for driving impaired by drugs other

than alcohol is that there is no scientific basis for specifying

a bodily fluid concentration that is indicative of impairment.

Successful prosecution has typically involved establishing

behavioral evidence of impairment coupled with evidence of

drug use, with the opinion that the drug use is likely to have

caused the impairment.

Several States have implemented per se laws for drugs. Drug

per se laws are not quite analogous to the alcohol impaireddriving per se laws now in effect in every State which make

it illegal to operate a motor vehicle with a blood alcohol concentration (BAC) of .08 grams per deciliter (g/dL) or greater.

Alcohol-impaired-driving per se laws are based on evidence

that all drivers are impaired at a BAC of .08 g/dL. Drug per

se laws are more analogous to zero-tolerance laws that make

it illegal to drive with certain drugs in the system.

The objective of this project was to determine the extent to

which States that have drug per se laws use them, and document any special concerns that arise when making and prosecuting an arrest under a drug per se law.

The National HighwayTraffic SafetyAdministration was also

interested in determining whether these laws are effective

in increasing driving under the influence of drugs (DUID)

arrests and convictions. To learn about drug per se laws,

NHTSA contracted with the Pacific Institute for Research

and Evaluation (PIRE).

DUID Laws

Several States have drug per se laws, which prohibit specified substances in drivers. The full research report contains

a summary of each State’s per se DUID law and State code,

including a list of any specified prohibited drugs. These

States’ criminal, court-ordered, and administrative sanctions

for DUID sanctions are also noted.

DUID Laws

Drug per se - 

Prohibits presence of specified 

drugs while person is driving/

in control of vehicle

AZ

DE

GA

IL

IN

IA

MI

MN

NV

OH

PA

RI

UT

VA

WI

Illegal for person under 21 

to drive with any amount of 

prohibited substance

NC

SD 

Illegal for a drug addict or 

habitual user to drive

CA

CO

ID

KS

WV

In addition to the States with drug per se laws; two additional States have per se laws for drivers under 21 years old

and five States prohibit a drug addict or habitual user from

driving a vehicle.

DUID Arrest Process

When a driver is pulled over for probable cause for impaired

driving, an officer will typically first conduct the SFST (Standardized Field Sobriety Tests). If the SFST and other indicators, such as a preliminary breath test, suggest that the driver

is impaired but has either a low BAC or has not consumed

alcohol, a drug recognition expert (DRE) may be called to

examine the suspect for signs of drug use. In many instances,

a DRE is not available and the arresting officer pursues the

case without this assistance. If the person is arrested for

DUID, a blood sample is taken and sent to a lab for analysis.

Methods

To obtain more in-depth information on whetherthe laws are

believed to be working well and accomplishing their goals,

Drug Per Se Laws: A Review of Their 

Use in the States
TRAFFIC TECH is a publication to disseminate information about

traffic safety programs, including evaluations, innovative programs, and new publications. Feel free to copy it as you wish. If you

would like to receive a copy, contact Angela H. Eichelberger, Ph.D.,

Editor, fax 202-366-7394, e-mail: angela.eichelberger@dot.gov.

1200 New Jersey Avenue SE., NTI-132

Washington, DC 20590

offense is a component within the State’s existing impaireddriving offense, and there is no indication in the records

whether the arrest is for alcohol or drugs. Additionally, some

States were not able to provide overall impaired-drivingarrest data, or information on convictions. At this time, there

is not sufficient available data to determine whether drug per

se laws increase arrests or convictions.

Most of the prosecutors and officers included in this study

believed that a drug per se law was beneficial. The prosecutors tended to believe that the DUID cases had high conviction rates, and with blood analysis evidence, typically few

cases required going to trial. However, the officers and prosecutors interviewed in a State without a per se law did not

feel hindered without that law and believed that most DUID

cases, especially ones involving officers trained in drug recognition, are pled guilty.

Across States, many noted that in arrests where both alcohol

and a drug were involved, the prosecutor will only pursue

the case for alcohol, as there is often no additional sanction

for the use of the drug.

How to Order

To order the report Drug Per Se Laws: A Review of Their Use 

in States, prepared by the Pacific Institute for Research

and Evaluation, write to the Office of Behavioral Safety

Research, NHTSA, NTI-130, 1200 New Jersey Avenue SE.

Washington, DC 20590, fax 202-366-7394, or download from

www.nhtsa.gov. Amy Berning was the project manager for

this study.

PIRE met with groups of State officials, prosecutors, and law

enforcement officers in a few States with drug per se laws.

To also examine the DUID arrest and prosecution process in

States without drug per se laws, PIRE met with representatives from one State without a per se law but with a strong

drug evaluation and classification (DEC) program, and one

State with no per se law and no DEC program.

Study Sites Per se law DEC Program

Arizona yes yes

Iowa yes yes

Wisconsin yes yes

Michigan yes no

Colorado no yes

West Virginia no no

Where possible, PIRE obtained States’ DUID arrest and conviction data. Our study design called for this data to be compared pre- and post-enactment of each State’s per se law, and

also between States with per se laws and States without these

laws.

Findings 

Although a key objective of this project was to determine

whether drug per se laws increase DUID arrests and convictions, a main finding was that for many States, the DUID