THE EFFECTS OF 0.08 BAC LAWS

Robert Apsler, Ph.D.

A.R. Char, M.S., MBA

Wayne M. Harding, Ed.M., Ph.D.

Rainbow Technology Inc.

and

Terry M. Klein

National Highway Traffic Safety Administration

April 1999

-iEXECUTIVE SUMMARY

Straightforward and powerful reasons exist for lowering the legal limit of blood alcohol

concentration (BAC) from 0.10 to 0.08. In 1964, Borkenstein et al. showed that drivers who had

been drinking were more likely to be involved in a crash than sober drivers, and that beginning

with low BACs, the greater the level of intoxication, the higher the probability of being in a crash. 

Other investigators have replicated and refined Borkenstein et al.'s original findings. More

recently, Mounce and Pendleton (1992) extended this line of research by showing that driver BAC

is associated with the probability of being responsible for a crash in which they were involved. 

Research also shows that virtually all drivers, even experienced drivers, are significantly impaired

with regard to critical driving tasks at 0.08 BAC. The strong relationship between BAC level,

probability of crash involvement, and increased impairment, has led a growing number of states to

lower their legal BAC limits. To date, 16 states and the District of Columbia have lowered the

BAC limit to 0.08 for adult drivers.

It is hypothesized that implementing a 0.08 BAC law has a synergistic effect on the other

components of the anti-drunk driving system, namely the enforcement, adjudication, judicial,

licensing, and public information and education components. The U.S. experience suggests that

combating drunk driving is most effective when ALL of the components are at play. This was the

approach espoused by the U.S. Department of Transportation as early as 1970, in its $88 million

Alcohol Safety Action Program, which emphasized a systems approach to reduce alcoholimpaired driving. Even with legislation itself, the enactment of multiple initiatives (often called

“omnibus bills”) has generally resulted in more public awareness, and often more impact, than the

enactment of single-initiative legislation. In the case of 0.08 BAC legislation, it is anticipated that

implementing such laws builds upon legislation and other activity already in place. The

expectation is that the publicity surrounding 0.08 BAC legislation serves to remind the public

about the dangers of drinking and driving and may catalyze the enforcement, judicial, and

licensing communities to refocus its efforts on the importance of removing drunk drivers from the

nation’s roads.

The objective of the current study was to review the fatal crash experience of all states that have

lowered their BAC limits to 0.08 and to determine the impact of this legislation on alcohol-related

fatalities. However, in several of these states, there was not sufficient experience with the lower

BAC limit to provide meaningful statistical inferences. At the time this study was begun, eleven

states had sufficient experience with 0.08 BAC laws to conduct a meaningful analysis.

In summary, our analysis found that the rate of alcohol involvement in fatal crashes declined in

eight of the states studied after the effective date of the 0.08 BAC law. Further, 0.08 BAC laws

were associated with significant reductions in alcohol-related fatalities, alone or in conjunction

with administrative license revocation (ALR) laws, in seven of the eleven states. In five of these

seven states, implementation of the 0.08 BAC law itself was followed by significantly lower rates

of alcohol involvement among fatalities. These results take into account any pre-existing

downward trends the states were already experiencing, due possibly to other factors such as the

presence of other laws, sobriety checkpoints, or a general societal trend for reduced alcohol

consumption. 
-iiTwo of the seven states which showed impact (California and Virginia) exhibited significant

reductions in alcohol-related fatalities when the 0.08 and ALR laws, implemented within about 6

months of one another, were modeled as a single intervention.

These findings are consistent with the hypothesis that 0.08 laws work best in conjunction with

other laws, especially ALR laws. All of the states which exhibited a significant association

between a 0.08 BAC law and a reduction in alcohol involvement already had an administrative

license revocation law in effect (Vermont, Kansas, North Carolina, Florida and New Mexico). In

two states the reductions occurred when 0.08 BAC and ALR laws were enacted in close temporal

proximity to each other (California and Virginia). 

Again, it is clear that many factors have been at work since the early 1980's, which have resulted

in long-term declines in alcohol-related fatalities in most states. Some of these factors were in

operation prior to the implementation of the 0.08 BAC laws. While it is difficult to pinpoint all

the factors that have been responsible for these long-term declines, it is likely that the declines

resulted from a combination of legislative, enforcement, judicial, sanctioning, and public

information activities implemented in the states. These analyses suggest that the 0.08 BAC laws

added significantly to this impact in several of the states studied, usually in conjunction with the

presence of administrative license revocation laws.

Reduction of the legal BAC limit from 0.10 to 0.08 also appears to be associated with a reduction

in beer consumption in 4 of the 5 states for which consumption data were available. The

association is strong in two of these five states (California and Vermont). The association in

California is weaker and is clouded by increased volatility following implementation of the 0.08

law. The absence of an association in Oregon could be due to an artifact. A substantial reduction

in annual beer consumption occurred two years before the 0.08 law was implemented. This sharp

reduction may have made it difficult for an additional reduction to occur.
-iiiTABLE OF CONTENTS

Executive Summary .......................................................... i

Introduction ............................................................... 1

The Impact of 0.08 Laws on Alcohol Consumption .................................. 2

The Impact of Lower BAC Limits on Motor Vehicle Crashes .......................... 9

 Very Low BAC Limits for Underage Drivers – Literature Review .................... 9

 Evaluations of 0.08 Laws – Literature Review .................................. 12

 Evaluations of Administrative License Revocation Laws – Literature Review ........... 13

Current Study Methods ...................................................... 15

 State-By-State Analyses ................................................... 18

 Discussion of Fatality Analyses .............................................. 30

References ................................................................ 35

Appendix (Graphs of Monthly State Fatalities with 12-Month Moving Averages) .......... 37
-iv-
1BAC refers to either blood alcohol concentration, stated as grams per deciliter (g/dl) of

blood, or breath alcohol concentration, stated as grams per 210 liters of breath.

The Effects of 0.08 Laws -1-

INTRODUCTION

Straightforward and powerful reasons exist for lowering the legal limit of blood alcohol

concentration (BAC1) from 0.10 to 0.08. Borkenstein et al. (1964) showed that: (1) drivers who

had been drinking were more likely to be involved in a crash than sober drivers, and (2) beginning

with low BACs, the greater the level of intoxication, the higher the probability of being in a crash. 

Other investigators have replicated and refined Borkenstein et al.'s original findings (Baker and

Spitz, 1970; Hurst, 1970; Farris, Malone, and Lilliefors, 1976; Mayhew et al., 1986; Zador 1991). 

For reviews of these and other research, see NHTSA (1991a) and NHTSA (1992). More

recently, Mounce and Pendleton (1992) extended this line of research by showing that driver BAC

is associated with the probability of being responsible for a crash in which they were involved. 

Research also shows that virtually all drivers, even experienced drivers, are significantly impaired

with regard to critical driving tasks, such as braking, lane changing, and divided attention, by the

time they reach 0.08 BAC (Moscowitz, 1988). The strong relationship between level of

intoxication and probability of crash involvement, as well as the impairment research, has led a

growing number of states to lower their legal BAC limits. To date, 16 states and the District of

Columbia have lowered the BAC limit to 0.08 for adult drivers.

While the desired impact of lowering BAC limits is obvious, predicting the actual effects is

complex because of many uncertainties. Who, for example, will be affected by lower BAC limits,

and what is the mechanism through which they will be impacted? To begin with, there is the

question of how many and which drinkers are aware of a change in BAC laws. Assuming that

drinkers know the legal limit, do they understand its meaning S not in terms of grams of ethanol

per deciliter of blood (g/dl), but in terms of how many drinks of alcohol (of what kind) they can

have without reaching or exceeding the limit? In other words, can drinkers correctly estimate the

number of drinks, or, if they cannot, do they consistently underestimate the number (see Apsler

and Harding, 1997). There is also the question of whether drivers know at what BAC level they

are too impaired to drive safely.

There are also questions about which drinkers are affected by lowering the BAC limit and how

they are affected. Perhaps all drinkers are affected in much the same way. Light drinkers decide

to drink less just to be safe, even though their previous level of drinking may have kept them well

below the new, lower BAC limit. Heavier drinkers also may decide to reduce the amount they

drink before driving in order to lessen their chances of being arrested for driving while

intoxicated. The scenario where light drinkers cut back their alcohol consumption to further

reduce their risk of an alcohol-related crash engenders opposition from alcohol-makers and

vendors. They argue that sales will suffer without significant benefits to public safety. Another

possibility is that the change in BAC laws will only affect the target group of heavy drinkers, who

contribute disproportionately to alcohol-related crashes. Or, the publicity accompanying changes

in BAC limits could contribute to a general anti-drinking climate and result in a broad decline in
The Effects of 0.08 Laws -2-

alcohol consumption that is not limited to drivers. Because of these and other uncertainties, it is

important to investigate what actually happens when states lower their BAC limits for drivers.
The Effects of 0.08 Laws -3-

PART I: THE IMPACT OF 0.08 LAWS ON ALCOHOL CONSUMPTION

One likely consequence of lowering BAC limits is that consumption of alcohol among drivers 

declines. While likely, a decline in consumption is not actually necessary for lowered BAC limits

to be effective in reducing crashes. Crashes should decline if drivers who drink heavily consume

their usual amount of alcohol and then wait long enough for their BAC to drop below .08 before

driving, or use a designated driver who does not drink, or drink in a location (e.g., home) where

they do not have to drive. However, it is probably much easier for most individuals to avoid

driving with a BAC greater than 0.08 by reducing their alcohol intake than by waiting for their

BAC to drop, or by planning ahead and using a designated driver. Even moderate drinkers could

decide to drink less before driving just to be certain that they do not exceed the new, lower BAC

limit.

METHODS

No suitable data exist for conducting a rigorous, direct test of the impact of 0.08 legislation on

alcohol consumption by drivers. The best available data consist of annual alcohol consumption

figures for each state and for the nation as a whole for the years 1977 through 1994 (Williams et

al., 1996). In this report, we present the data on beer consumption (data on wine and liquor are

also available), the most widely consumed alcoholic beverage and the beverage most frequently

implicated in alcohol-related arrests and crashes. Beer is the preferred type of alcoholic beverage

of drinking drivers by a factor of about two-to-one over other beverages (NHTSA, 1990). 

Unfortunately, several factors severely restricted the utility of these data. First, the data reflect

consumption for all drinkers and do not differentiate between drivers and non-drivers. Second,

the data are available only on an annual basis, thereby providing few data points. Third, only five

of the thirteen 0.08 states (as of 1997) passed their laws early enough so that at least three data

points were available following implementation of the law. Data from these five states could not

be combined in an effort to improve reliability, since their laws were passed at different times.

Because of the paucity of data points and the inadvisability of combining data across states, we

relied on visual examination of plotted consumption data. The analysis took two factors into

account. First, each state's annual alcohol consumption trend during the period prior to the 0.08

law was compared with the annual consumption trend in the period following the law's

implementation. Second, each state's alcohol consumption trends were compared with national

trends. It was necessary to show that changes in state alcohol consumption that coincided with

the reduction in the legal BAC limit were not simply a consequence of external factors reflected in

similar changes in the national pattern of alcohol consumption. To make detection of changes in

consumption trends clearer, separate regression lines were plotted for the period before and the

period after implementation of the 0.08 law.
The Effects of 0.08 Laws -4-

RESULTS

Utah

As Exhibit 1 shows, a dramatic reduction in Utah's annual beer consumption occurred from 1982

to 1983, just before implementation of the 0.08 law. This phenomenon of a law producing an

impact on behavior shortly before implementation is not uncommon in the traffic safety area. The

most likely explanation is that passage of the 0.08 law was preceded by extensive news coverage

which sensitized many people to the issue of drunk driving and motivated them to drink less. 

Official implementation of the law did not produce additional behavior change. Aside from the

dramatic drop in alcohol consumption immediately preceding implementation of the lower legal

BAC, Utah's annual consumption closely tracks the national pattern of alcohol consumption.

Exhibit 1

Mean Beer Consumption in Utah

1977 to 1994
The Effects of 0.08 Laws -5-

Oregon

Trends in Oregon's alcohol consumption differed markedly from those in California and Maine. 

As Exhibit 2 shows, annual beer consumption in Oregon decreased substantially between 1981

and 1982, before the legal BAC limit was reduced in 1983. After dropping below the national

average in 1981 and 1982, annual beer consumption continued to decrease, but it decreased at

roughly the same rate as the national average. Thus, the reduction in the legal BAC limit appears

to have had no effect on beer consumption in Oregon.

Exhibit 2

Mean Beer Consumption in Oregon

1977 to 1994
The Effects of 0.08 Laws -6-

Maine

As Exhibit 3 shows, the results for Maine are similar to those for California. The slope of the

post-implementation regression line drops more steeply than the pre-implementation period

regression line. Furthermore, the pre-implementation period regression line is nearly parallel to

the plot for average beer consumption in the United States, suggesting that Maine residents

responded to the same influences that affected the country as a whole. In the postimplementation period, however, Maine's annual beer consumption declined somewhat more

rapidly than the United States average, indicating that different influences were affecting Maine

versus the rest of the country. 

Exhibit 3

Mean Beer Consumption in Maine

1977 to 1994
The Effects of 0.08 Laws -7-

California

As Exhibit 4 shows, beer consumption in California decreased following implementation of the

0.08 law in 1990. The decrease in consumption is evidenced in two ways. First, the downward

slope of the post-implementation regression line is steeper than the slope of the pre-implementation

line. Second, the plot of California's annual beer consumption closely tracked national annual

beer consumption from 1982 through 1989. In 1990, however, California's average beer

consumption fell under the national average and remained beneath the national figures through

1994.

Exhibit 4

Mean Beer Consumption in California

1977 to 1994
The Effects of 0.08 Laws -8-

Vermont

A substantial drop in Vermont's annual beer consumption may be associated with implementation

of the lower legal BAC (see Exhibit 5). As was the case in Utah, annual beer consumption

decreased strongly just before implementation of the law (from 1990 to 1991). However, national

beer consumption decreased strongly during the same period. Thus, the factors responsible for

the national decline in beer consumption probably also affected Vermont. The decline in Vermont

continued in the year following implementation of the law, while the national trend leveled off. 

Here, Vermont beer consumption clearly diverged from the national trend and may well have been

the result of lowering the legal BAC limit.

Exhibit 5

Mean Beer Consumption in Vermont

1977 to 1994
The Effects of 0.08 Laws -9-

Conclusion

Reduction of the legal BAC limit from 0.10 to 0.08 appears to be associated with a reduction in

beer consumption in four of the five states. The association is strong in only two of these five

states: California and Vermont. The association in California is weaker and is clouded by

increased volatility following implementation of the 0.08 law. The absence of an association in

Oregon could be due to an artifact. A substantial reduction in annual beer consumption occurred 

two years before the 0.08 law was implemented. This sharp reduction may have made it difficult

for an additional reduction to occur.
The Effects of 0.08 Laws -10-

PART II: THE IMPACT OF LOWER BAC LIMITS ON MOTOR VEHICLE

CRASHES

Very Low BAC Limits for Underage Drivers

Most of the research examining the impact of lowering BAC limits has investigated the effects of

very low BAC limits targeted at underage drivers. Blomberg's (1992) evaluation of Maryland's

0.02 law for drivers under the age of 21 is the most rigorous of these studies. His research used a

time series-intervention analysis research design with a non-equivalent control group to test the

impact of the 0.02 law, and also whether an experimental education campaign enhanced the law's

effects. Models developed with Box-Jenkins analysis were used to characterize the trends in

crash-involved drivers under the age of 21 judged by the investigating officer to have been

drinking. The two models presented by Blomberg are consistent with a significant decline in

crashes resulting from implementation of the 0.02 law. Conversely, analyses of time series for

two types of drivers who should not have been influenced by the new law S drivers 21 and older

judged to have been drinking and drivers under the age of 21 not judged to have been drinking S

produced no significant changes. Therefore, the reduction in crashes observed for young drivers

judged to have been drinking cannot be due to a general decrease in either alcohol-involved

crashes for drivers of all ages or of all crashes involving drivers under the age of 21.

An education campaign aimed at enhancing the effects of the law lowering the BAC limit for

drivers under the age of 21 was administered in two Maryland counties. It consisted of: (1) the

dissemination of information about the new law through the mass media and distribution of

brochures and posters; (2) efforts to inform police agencies about the law and to engage them in

the public information campaign; and (3) invitations asking local groups to help with the

information campaign. Pre and post surveys conducted in both treatment and control counties

showed small but significant increases in youths' estimates of the percentage of drinking drivers

arrested on a typical night. Youths in the treatment counties were also more likely than youths in

control counties to know the BAC limit in the new law. More importantly, crash data also

supported the effectiveness of the education campaign. The percentage of drivers in crashes

under age 21 who were judged to have been drinking declined substantially more in the counties

where the education campaign was conducted than in control counties (44% in the treatment

counties and 30% in the control counties).

In sum, Maryland's 0.02 law had the intended effect of reducing the number of crash-involved

drivers under the age of 21 judged to have been drinking. The addition of a public information

and education campaign directed at increasing awareness of the new law heightened the effect. 

Finally, the care with which the analyses explored and discarded the possibility that the results

were due to factors other than the 0.02 law markedly strengthen confidence in the validity of the

findings. One weakness of this study was the use of police-reported alcohol involvement as the

measure in crashes, rather than BAC test results. Studies show that police crash reports tend to

underestimate alcohol involvement in crashes absent any BAC testing.

Hingson et al. (1991) evaluated the effectiveness of lowered BAC limits for underage drivers by

comparing adolescent crashes in states with and without these laws. Four states with low BAC
The Effects of 0.08 Laws -11-

limits for adolescents were paired with the closest state having the most similar drinking age laws,

but no low BAC limit for underage drivers. Maine was paired with Massachusetts, New Mexico

with Arizona, North Carolina with Virginia, and Wisconsin with Minnesota. 

The authors' endorsement of low BAC limits for adolescents is not completely supported by their

data. For each state, Hingson et al. aggregated the number of adolescent night fatal crashes

during a pre-law period and then again in a post-law period (the length of both periods was the

same within a pair of states but varied among pairs). The authors state, "As can be seen in

[Exhibit 6], night fatal crashes among adolescents in Maine were 38% lower in the post-law

period than they had been in the pre-law period" (p. 121). While this statement is accurate,

inspection of their data (see Exhibit 6) indicates that the decline was apparently unrelated to

Maine's 0.02 law. A large decline in Maine teen night fatal crashes occurred from 1980 to 1981,

long before the 0.02 law was enacted in mid-1982. Inspection of the authors' figures for

Wisconsin and Minnesota night fatal crashes involving teenagers show long, gradual trends with

no hint of an abrupt effect before or after passage of the low BAC laws for underage drinkers. In

sum, the authors' results could have been an artifact of the time periods and comparison states

chosen for the study. The crash trends they present for teenagers provide no clear evidence of an

impact of the low BAC laws.

Hingson, Heeren, and Winter (1994) studied the impact of laws lowering BAC limits for young

drivers in 12 states where such laws had been in place for at least one year. In addition, they

examined differences among four specific BAC limits that had been established for young drivers: 

0.00, 0.02, and 0.04 to 0.06. Each of the 12 states that had lowered its BAC limit for young

drivers was paired with a nearby state in which BAC limits were the same for drivers of all ages. 

Control states were matched "... as closely as possible for legal drinking age and timing of

changes in that law." Further details of the matching process were not presented. The authors

employed a surrogate measure of alcohol-involved crashes S single-vehicle night fatal crashes. In

order to control for the total number of fatal crashes, they created a ratio of the number of singlevehicle night fatal crashes to the total number of crashes. The laws changing BAC limits for

young drivers affected different age groups in different states. The age ranges targeted by

different states included drivers under age 18, drivers under age 19, drivers under age 21, and

drivers under age 22. The authors did not include the target age group in their analysis.

A notable feature of the data is their great variability. The authors present a table showing the

proportion of fatal crashes that involved single vehicles at night among young drivers for pre- and

post-law periods in each treatment and control state. The percentage change from pre- to postlaw periods among states that lowered their BAC limits for young drivers ranged from a decrease

of 31% (the desired direction of change) to an increase of 201%. Variation in the control states

was less, ranging from a decrease of 22% to an increase of 46%. 

The authors employed the unusual analytical approach of aggregating all fatalities in the low BAC

states to compute a single, overall proportion of single-vehicle night fatal crashes involving teens

to all fatal crashes. This overall proportion decreased more from pre- to post-law periods (a

decrease of 16%) than the single proportion calculated by combining the fatalities from all control

states (an increase of 1%). If the authors had treated each state as a separate case, they would
The Effects of 0.08 Laws -12-

have reached a different conclusion. The average change for low BAC states was an increase of

23% from pre- to post-law periods in the proportion of single-vehicle night fatal crashes involving

teens to the total number of fatal crashes. The average change for control states was an increase

of 20%. The authors' results appear to depend more on which states were chosen as controls and

on the manner in which the data were aggregated than on the effects of the BAC laws. 

Exhibit 6

Massachusetts and Maine Night Fatal Crashes Involving Teenage Drivers

Before and After Maine's 0.02 Law for Teenage Drivers
The Effects of 0.08 Laws -13-

Evaluations of 0.08 Laws

The authors of the first attempt to evaluate a 0.08 law emphasized two crucial factors that

severely limited the study's usefulness (NHTSA, 1991b). The study was unable to distinguish

between the effects of California's 0.08 law and an administrative per se law that became effective

six months later (complicated by the fact that public information about both new laws began

months prior to the effective date of the first). Furthermore, only six months of data were

available for the period following passage of the administrative per se law. While this study did

find an effect for 0.08 and not for ALR, the authors point out that the two laws were implemented

too close to one another separate the effects of one law from the other.

One study published in a refereed journal examined the effect of lowering legal blood alcohol

limits to 0.08 (Hingson, Heeren, and Winter, 1996). However, questions about the research

design and methods may undermine their conclusion that adoption of a 0.08 law reduces fatal

crashes. To evaluate 0.08 laws, the authors paired the five states that lowered their BAC limits

from 0.10 to 0.08 prior to 1992 with a "... nearby state that retained a 0.10% limit." The

resulting pairs were: Utah with Idaho, Oregon with Washington, Maine with Massachusetts,

California with Texas, and Vermont with New Hampshire. They chose as a dependent measure

the proportion of fatal crashes involving fatally injured and other drivers with blood alcohol levels

at or above 0.08.

The authors provide no additional information about how the comparison states were chosen and

do not explore the effect on the results of selecting alternative states for the comparison. Several

anomalies among their pairings of states suggest that the results of the study may not be

generalizable. For example, Maine, a largely rural state, was paired with Massachusetts, a state

with a large, cosmopolitan, urban center. Unlike other pairings, Texas and California are not

"nearby." The danger of relying on a single comparison state for each 0.08 state is demonstrated

by the extreme variability among the comparison states. In the control state of Idaho, for

example, the proportion of fatal crashes with a fatally injured driver whose blood alcohol was

0.08 or more increased 43% from the before period (before Utah passed its 0.08 law) to the after

period. The comparable change in New Hampshire, the comparison state for Vermont, was a

decrease of 31%. Not only did these two states change in opposite directions, the absolute

magnitude of their changes is more than double the change in any other comparison or treatment

state. 

This study also suffers from the weakness noted previously with Hingson et al. (1991) and

Hingson, Heeren, and Winter (1994), namely that the pre- to post-law comparisons are based on

aggregated data on fatal crashes. The possibility exists, then, that the aggregate change may mask

year to year variability within a state that is not consistent with the hypothesis that the 0.08 law

lowered fatal crashes. For example, there may have been large reductions in crashes before

passage of the law, but this troubling fact is obscured by combining crash data for several years

prior to the change in the BAC laws.

Even assuming that the authors' claim of a reduction in alcohol-involved fatal crashes for four of

the five 0.08 states, relative to their control states, is correct, their conclusions about the cause of
The Effects of 0.08 Laws -14-

the reduction are unwarranted. The article's abstract states under Conclusions, that "If all states

adopted 0.08 legal blood alcohol limits, at least 500 to 600 fewer fatal crashes would occur

annually." However, in the discussion section of the article, the authors observe that all five of

the 0.08 states had administrative license revocation laws in place during the period of the study. 

Furthermore, three of these states implemented their license revocation law within one year of

their 0.08 law. Conversely, only one of the comparison states had an administrative license

revocation law during the study period. Since the authors were unable to differentiate between

the impacts of the two laws, it is impossible to know whether the 0.08 law contributed anything

unique to a reduction in fatalities. 

In an early NHTSA study, which was published in a peer reviewed medical proceedings (Johnson

and Fell, 1995), decreases in various measures of alcohol involvement in fatal crashes were found

in 4 out of 5 states after implementation of 0.08 laws. The study did not attempt to separate or

control for the presence of other laws, most notably ALR, that might have been implemented

around the time of 0.08, nor was any attempt made to account for possible long-term trends in the

data.

Evaluations of Administrative License Revocation Laws

As Hingson, Heeren, and Winter (1996) noted, several states lowered their BAC limits to 0.08

within a few months after implementing administrative license revocation laws. Administrative

license revocation laws allow the immediate, administrative suspension of a driver's license when a

driver: (1) is arrested for DUI, (2) agrees to a chemical test for the presence of alcohol, and (3)

produces a BAC at or above the legal BAC limit. The logic behind these laws is that

administrative license revocation is applied swiftly and with certainty to individuals arrested for

DUI. This insures that a large percentage of DUI offenders receive what has been found to be

one of the most effective sanctions against DUI recidivism.

Several investigators have found that administrative license revocation laws are effective general

deterrents in reducing crashes (Zador et al. 1988; Klein 1989; Lacey et al. 1990). Other research

found that implementing administrative license revocation laws is cost-effective for states (Lacey,

Jones, and Stewart 1991) and that, typically, license revocation does not result in a severe

negative impact on offenders' jobs and income. It is because of the greater support shown for the

effectiveness of administrative license revocation laws that they cannot be ignored by evaluations

of 0.08 laws. Analyses of the impact of lowering BAC limits must identify and attempt to isolate

the impact of administrative license revocation to be certain that its effects are not mistaken for

the results of 0.08 legislation.
The Effects of 0.08 Laws -15-

CURRENT STUDY METHODS

Dependent Measures

To assess the impact of 0.08 laws, we chose three indices maintained for all states since 1982 by

NHTSA's Fatality Analysis Reporting System (FARS). FARS contains information about motor

vehicle crashes on public roadways that result in an occupant's or nonmotorist's death within thirty

days of the crash. We examined two possible effects of 0.08 legislation. The first is that of

reducing the level of intoxication among individuals who drive after drinking. This was measured

with a FARS index of the number of fatalities in crashes in which any driver produced a BAC $

0.10. If individuals decrease the amount they drink before driving, then fewer drivers in fatal

crashes should demonstrate a relatively high level of intoxication after 0.08 laws take effect. 

Another possible effect of lower BAC limits is that many individuals become more cautious about

the amount of drinking before driving. Even individuals who do not drink enough to reach a BAC

of 0.10 might reduce the amount they drink before driving. Thus, 0.08 legislation could decrease

the number of crashes in which drivers are moderately impaired. This possibility was measured

with a FARS index of the number of fatalities in which any driver tested positive for alcohol

(BAC > 0.00).

The third FARS index was employed as an internal comparison (control) measure to help isolate

the causal role of 0.08 legislation. There is no reason to expect that lowering BAC limits will

affect drivers who do not drink. Thus, if 0.08 legislation operates as anticipated, the number of

intoxicated drivers involved in fatal crashes should decline as a result of the law while the number

of sober drivers involved in fatal crashes remains unaffected. Conversely, if a decline occurs for

both intoxicated and sober drivers involved in fatal crashes, the cause of the reduction might be a

general phenomenon that affects both intoxicated and sober drivers. The third FARS index was

chosen to test whether reductions occurred for only drinking drivers or for both drinking and

sober ones. This index consists of the ratio of the number of fatalities in crashes involving

intoxicated drivers (BAC > 0.10) to the number of fatalities in crashes with no drinking drivers

(BAC=0.00).

Analyses

Time series analysis is currently the most powerful statistical tool employed by traffic safety

researchers for assessing the impact over time of laws aimed at changing driving behavior. With

time series analysis, it is possible to detect the impact of an intervention, such as 0.08 legislation,

and also distinguish the effects of that intervention from many other influences on driving

behavior, such as seasonal variation, long-term trends unrelated to the passage of a new law, and

implementation of other legislation, such as administrative license revocation.

We used the Box-Jenkins (1970) ARIMA modeling process for analyzing each of the three FARS

indices for each state that: (1) had lowered its BAC limit from 0.10 to 0.08, and (2) for which a

minimum of one year of FARS data existed for the period following implementation of the law. 

The modeling process consisted of three steps. First, the characteristics of a time-series were

examined and a tentative model was derived. Second, the parameters of the tentatively identified

model were estimated. Third, the model was checked for statistical accuracy (over and under
The Effects of 0.08 Laws -16-

specified) and the residuals were checked for randomness. Initially, each series was plotted for

visual observation. If any extreme values were observed, they were smoothed using the averages

(this was crucial in dealing with the ratio series). Each series was tested for stationarity. If a

series was not stationary, differencing (regular and/or seasonal) was performed to achieve

stationarity. Autocorrelation and partial autocorrelation (ACF and PACF) procedures were

employed to arrive at a tentative autoregressive-integrated-moving average (ARIMA) model. 

Using the tentatively identified model, we estimated parameters and checked for statistical

significance, and residuals were analyzed for randomness. Based on these diagnostics, the

ARIMA model was adjusted, and parameters were re-estimated. This iterative procedure was

repeated until a statistically correct ARIMA model was achieved.

The above univariate process extracts all of the statistical information inherent in serially and/or

seasonally correlated data, such as crash-related measures. However, time-series are often

affected by various external events commonly known as interventions. When such interventions

are known to us, we can evaluate their effect by using the "intervention models" of Box and Tiao

(1975). 

In the case of a single intervention, the form of the Box-Tiao intervention model is

Yt = C +

ù (B) Ét

 + Í t

ä(B)

Yt is the time series under study. C is a constant. The rational polynomial (ù (B)/ä(B))

characterizes the effects of the intervention. The operator in the numerator, ù (B), represents the

impact of the intervention and the length of time it takes the intervention to affect the time series. 

The operator in the denominator, ä(B), represents the way in which the effect of an intervention

dissipates. Ét is a binary vector that defines the period of the intervention. It is assigned the value

0 for the pre-intervention period and the value 1 for the intervention and post-intervention period. 

Í t is the noise series, or disturbance and can be modeled as an ARIMA process. 

In the present situation, two intervention variables are possible, namely 0.08 laws (É1t) and ALR

laws (É2t). Therefore, the intervention model is of the type:

Yt = 

ù 1(B) É1t + ù 2(B) É2t + Í t

ä1(B) ä2(B)

Since we are using differenced series to achieve stationarity, the constant term, C, representing a

long-term serial or annual trend, may or may not appear. In all our analyses of FARS data, C was

zero. The steps in the intervention analysis are similar to those used for univariate analysis and

consist of identifying the model, estimating the parameters, and diagnostic checking and

improving the model until a statistically correct model is obtained. The objective of this process is

to determine whether or not the transfer functions, which represent the impact of a law, are

statistically significant.
The Effects of 0.08 Laws -17-

Exhibit 7

Effective Dates of 0.08 Laws and Administrative License Revocation Laws

State 0.08 Date ALR Date

California 1/90 7/90

Florida 1/94 10/90

Kansas 7/93 7/88

Maine 8/88 1/84

New Hampshire 1/94 7/92

New Mexico 1/94 7/84

North Carolina 10/93 10/83

Oregon 10/83 7/84

Utah 8/83 8/83

Vermont 7/91 12/89

Virginia 7/94 1/95

Separate analyses of 0.08 and administrative license revocation laws were conducted on a stateby-state basis in order to assess the independent impact of these two types of legislation. 

However, it is unreasonable to expect that the analyses can distinguish independent effects of

these laws in states where they were passed within close temporal proximity of one another, e.g.,

one year or less, as was the case in California, Oregon, Utah, and Virginia. This is especially true

since the analysis considers data back to 1982. For example, California’s 0.08 law was in effect

during January 1990-December 1995, while ALR was in effect during July 1990-December 1995. 

With only six months between the two laws, there is little or no chance that any type of analysis

could distinguish between the individual effects of the two laws. The remaining seven states

enacted their 0.08 legislation more than one year after passage of an administrative license

revocation law (Florida, Kansas, Maine, New Hampshire, New Mexico, North Carolina, and

Vermont). 

State-by-State Analyses

The state-by-state analyses of the impact of 0.08 BAC and ALR laws are presented in

chronological order, based on the effective date of the 0.08 BAC law. In most cases, these states

implemented administration license revocation laws prior to or (essentially) coincident with 0.08

BAC laws.
The Effects of 0.08 Laws -18-

Exhibit 8

Utah

BAC Level Ratio

> 0.10 > 0.01 0.00 > 0.10/0.00

0.08 & ALR

Aug 1, 1983

Estimate -0.7123 -0.6672 1.1395 -0.0870

Std Error 0.8766 1.0107 1.3176 0.0624

t-value -0.81 -0.66 0.86 -1.39

Note: Bold italics indicates statistically significant reduction (á=0.05, one-tailed test, t = -1.645)

Both the ALR law and the 0.08 law became effective on August 1, 1983 in the State of Utah,

leaving only 19 months of baseline data upon which to make an assessment of the combined

effects of 0.08 and ALR. Therefore, any estimates should be interpreted with caution. None of

the graphical presentations of these data indicate any noticeable shift before vs. after the

implementation of these two laws; the statistical models corroborate this observation, with none

of the measures showing significant changes before vs. after the August 1983 effective date. 

However, another factor worth noting for the State of Utah in 1982 is that their alcoholinvolvement rate in fatal crashes was substantially lower than the national average to begin with,

and lowering it even further would probably have been difficult.

Exhibit 9

Oregon

BAC Level Ratio

> 0.10 > 0.01 0.00 > 0.10/0.00

0.08

Oct 15, 1983

Estimate 2.6223 4.3968 -0.4142 0.1574

Std Error 2.2225 2.5600 2.5991 0.1168

t-value 1.18 1.72 -0.16 1.35

ALR

Jul 1, 1984

Estimate -4.9693 -6.4567 8.6646 -0.6032

Std Error 2.0430 2.3676 2.2875 0.1044

t-value -2.43 -2.73 3.79 -5.78

Note: Bold italics indicates statistically significant reduction (á=0.05, one-tailed test, t = -1.645)

Oregon’s 0.08 law became effective on October 15, 1983 and the ALR law on July 1, 1984. Due

to the relatively early implementation dates for the two laws, there are not much historical data to
The Effects of 0.08 Laws -19-

perform reliable analyses. To complicate matters, the two laws became effective less than ten

months apart, so any attempt to develop separate estimates for the two laws will suffer from the

potentially confounding influences of each piece of legislation, and the surrounding public

information, upon one another. Visual inspection of the graphs of high-BAC fatalities and

alcohol-related fatalities leaves the distinct impression that there was little impact in the 2-3 years

after both 0.08 and ALR became effective. The most dramatic changes in these alcohol series

appear to have begun around the spring of 1990, where both high-BAC and alcohol-related

fatalities dropped relatively precipitously, and remained at this lower level throughout the analysis

period (December 1995). The fact that this occurred 5-6 years after implementation of these laws

strongly suggests that some other factor was at play. At the same time, sober fatalities were

increasing throughout the period 1982 through 1989, approximately doubling in this seven-year

period, which is probably the driving force behind the decline in the high-BAC to sober fatality

ratio, which demonstrated a significant decline before vs. after the July 1984 implementation of

ALR. In spite of the short interval between the two laws, the ratio series did not decline until

after ALR implementation.

Exhibit 10

Maine

BAC Level Ratio

> 0.10 > 0.01 0.00 > 0.10/0.00

0.08

Aug 4, 1988

Estimate -0.4384 -0.5637 0.6980 0.0887

Std Error 0.9613 1.1278 0.6542 0.1573

t-value -0.46 -0.50 1.07 0.56

ALR

Jan 1, 1984

Estimate 0.9481 1.7187 2.0892 0.1030

Std Error 0.8708 1.0194 0.9238 0.1415

t-value 1.09 1.69 2.26 0.73

Trend term Estimate -0.3054 -0.3681 -0.0607

Std Error 0.1350 0.1585 0.0219

t-value -2.26 -2.32 -3.07

Note: Bold italics indicates statistically significant reduction (á=0.05, one-tailed test, t = -1.645)

Maine’s ALR law became effective on January 1, 1984 and the 0.08 law on August 4, 1988. 

Unfortunately, there are only 24 months of historical baseline data available to analyze the effect

of the ALR law. From a conceptual standpoint, the 24-month baseline period is less valuable than

would 24 months of experimental experience at the end of the data series. Thus, while the

analysis considered the January 1984 implementation of ALR, the reliability of these estimates, as
The Effects of 0.08 Laws -20-

indicators of ALR effectiveness, is suspect. As Maine is a relatively small state, monthly fatalities

are of relatively low frequency. However, the low level of monthly fatalities still exhibits some

fairly strong tendencies, including a 12-month seasonal cycle and an overall long-term downward

trend. This trend term was estimated in the statistical models, which was found to be statistically

significant in the high-BAC and alcohol-related fatality series, as well as in the high-BAC to sober

fatality ratio. In the presence of this significant downward trend, neither of the reductions in highBAC and alcohol-related fatalities after the August 1988 implementation of the 0.08 BAC law

were found to be statistically significant. The analysis of the ratio series, also exhibiting a

significant long-term trend, did not find statistically significant reductions associated with either

0.08 BAC or administrative license revocation.

Exhibit 11

California

BAC Level Ratio

> 0.10 > 0.01 0.00 > 0.10/0.00

0.08

Jan 1, 1990

Estimate -7.4815 -6.3439 15.1137 -0.0669

Std Error 9.5967 11.4227 11.3757 0.0609

t-value -0.78 -0.56 1.33 -1.10

ALR

Jul 1, 1990

Estimate -33.0588 -42.4927 -34.9109 -0.0445

Std Error 9.6122 11.4237 11.2403 0.0604

t-value -3.44 -3.72 -3.11 -0.74

Note: Bold italics indicates statistically significant reduction (á=0.05, one-tailed test, t = -1.645)

California’s 0.08 law became effective on January 1, 1990 and the ALR law on July 1, 1990. Due

to the temporal proximity of the effective dates of these laws, any observed effect may be due to

either one or the combined effect of both of these laws. California experienced a statistically

significant decrease of 33 high-BAC fatalities (BAC > 0.10+) per month associated with the July

1990 ALR effective date, and a significant reduction of 42 alcohol-related fatalities per month. 

During the same time period, there was a statistically significant decrease among sober fatalities of

approximately 35 per month. The combination of high-BAC fatalities per sober fatalities (ratio)

did not exhibit a significant decline. As stated earlier, the implementation of the 0.08 and ALR

laws occurred only six months apart. In light of this, it seemed reasonable to estimate a statistical

model using only one intervention, beginning January 1990, to represent the “combined” effect of

both the 0.08 and ALR laws. The results of this analysis appear below.
The Effects of 0.08 Laws -21-

Exhibit 11a

California – Supplemental Analysis of Combined 0.08 & ALR Intervention

BAC Level Ratio

> 0.10 > 0.01 0.00 > 0.10/0.00

Combined

Effect of

0.08 & ALR

Jan 1, 1990

Estimate -26.7105 -31.4670 -9.8774 -0.0977

Std Error 6.9125 8.5888 8.1865 0.0425

t-value -3.86 -3.66 -1.21 -2.30

Note: Bold italics indicates statistically significant reduction (á=0.05, one-tailed test, t = -1.645)

As can be seen in the above Exhibit, both high-BAC fatalities and alcohol-related fatalities exhibit

statistically significant decreases before vs. after January 1990. In contrast to the previous

analysis, however, the ratio of high-BAC to sober fatalities now yields a statistically significant

reduction, associated with the combined effect of 0.08 and ALR, which is represented in the

analysis as a single intervention beginning in January, 1990.

Exhibit 12

Vermont

BAC Level Ratio

> 0.10 > 0.01 0.00 > 0.10/0.00

0.08

Jul 1, 1991

Estimate -1.0317 -1.5047 1.2823 -0.4824

Std Error 0.5122 0.6817 0.7018 0.2299

t-value -2.01 -2.21 1.83 -2.10

ALR

Dec 1, 1989

Estimate -0.1440 -0.3516 -0.8188 -.0809

Std Error 0.4813 0.6509 0.6839 0.2247

t-value -0.30 -0.54 -1.20 0.36

Note: Bold italics indicates statistically significant reduction (á=0.05, one-tailed test, t = -1.645)

Vermont’s ALR law became effective in December 1989, and 0.08 BAC became effective in July

1991. Being a small state, Vermont’s data series show a great deal of month-to-month variability. 

None of the alcohol series, nor the sober fatalities nor the ratio show any statistically significant

declines associated with the implementation of ALR. On the other hand, both high-BAC and

alcohol-related fatalities, as well as the ratio of high-BAC to sober fatalities show significant

reductions after the implementation of law 0.08 law in July 1991. A trend term introduced into
The Effects of 0.08 Laws -22-

the statistical model failed to reach statistical significance (t = -0.75) and was, therefore, dropped

from the model.

Exhibit 13

Kansas

BAC Level Ratio

> 0.10 > 0.01 0.00 > 0.10/0.00

0.08

Jul 1, 1993

Estimate -0.4118 -1.5406 3.6169 -0.1475

Std Error 1.2679 1.3730 1.3954 0.0689

t-value -0.32 -1.12 2.59 -2.14

ALR

Jul 1, 1988

Estimate -1.0843 -2.1598 -2.9491 0.0006

Std Error 1.1186 1.1343 1.0888 0.0522

t-value -0.97 -1.90 -2.71 0.01

Note: Bold italics indicates statistically significant reduction (á=0.05, one-tailed test, t = -1.645)

Kansas’ ALR law was effective on July 1, 1988, and the 0.08 law became effective on July 1,

1993. Neither the early implementation of ALR nor the later 0.08 law was associated with a

statistically significant reduction in high-BAC fatalities, which appeared to reach a peak around

January 1987 and then begin to decline, a full 18 months before ALR became effective. These

fatalities again began to decline around January 1991, approximately midway between the

implementation of the two laws. This same pattern is observed for alcohol-related fatalities,

except that the reduction associated with ALR, which was about double that for high-BAC

fatalities (2.1598 vs. 1.0843 per month) was found to be statistically significant. The pattern for

sober fatalities is very similar, with the major distinguishing feature that in January 1993, sober

fatalities experienced a relatively large increase, and remained at this increased level during the

period January 1993-December 1995. The ratio of high-BAC to sober fatalities exhibited

essentially no change before vs. after the July 1988 ALR implementation. In contrast, however,

this ratio was found to be significantly less during the period of the BAC 0.08 law (beginning July

1993). A review of the fatality ratio graph indicates that this series began to decline in early 1991,

several years before 0.08 BAC became effective. A trend term, added to the statistical model,

was found to be nonsignificant (t = -0.64) and thus, it was dropped from the model.
The Effects of 0.08 Laws -23-

Exhibit 14

North Carolina 

BAC Level Ratio

> 0.10 > 0.01 0.00 > 0.10/0.00

0.08

Oct 1, 1993

Estimate -2.3864 -2.4834 9.4335 -0.0765

Std Error 2.3523 3.0269 2.4815 0.0426

t-value -1.01 -0.82 3.80 -1.80

ALR

Oct 1, 1983

Estimate 1.3357 2.3339 21.1776 -0.2219

Std Error 2.4598 3.1662 2.7483 0.0447

t-value 0.54 0.74 7.71 -4.97

Trend Term Estimate -1.1769 -1.5020 -0.0158

Std Error 0.2603 0.3350 0,0047

t-value -4.52 -4.48 -3.37

Note: Bold italics indicates statistically significant reduction (á=0.05, one-tailed test, t = -1.645)

North Carolina’s ALR law became effective on October 1, 1983 and the 0.08 law on October 1,

1993. This early implementation of ALR yields only 22 months of baseline data for studying the

impact of ALR. A review of the respective graphs indicates little change before a downturn that

began around January 1989, over five years after implementation of ALR. A similar pattern of

change is associated with the 0.08 BAC law, which became effective in October 1993. These

same graphs indicate that high-BAC and alcohol-related fatalities began a long-term decline in

early 1987, which appeared to accelerate beginning around January 1992, about 21 months prior

to 0.08 implementation. The statistical models incorporated a long-term trend in each of the

models estimated, which appeared to account for most of the decline in the alcohol-related and

high-BAC fatality series. However, for the high-BAC to sober fatality ratio, statistically

significant reductions (t = -1.80 for 0.08 and -4.97 for ALR, with a critical value of -1.645 for á =

0.05 one-tailed test) were found for both 0.08 and ALR, in light of a statistically significant longterm downward trend. The reduction around the implementation of 0.08 was relatively

pronounced and very stable, remaining at this lower level throughout the remainder of the time

period under study (December 1995). At the same time, sober fatalities began a pronounced

climb beginning in January 1993 and continued to increase through December 1995, leading to a

pronounced decline in the ratio of high-BAC to sober fatalities during the 0.08 BAC law time

period. North Carolina has unusually strict enforcement of DWI and the arrest rate is higher than

the national average. Several checkpoint campaigns were initiated in the 1990's which could

account for the decrease that was observed to have begun in 1992.
The Effects of 0.08 Laws -24-

Exhibit 15

Florida

BAC Level Ratio

> 0.10 > 0.01 0.00 > 0.10/0.00

0.08

Jan 1, 1994

Estimate -10.6090 -12.2759 20.8136 -0.1453

Std Error 2.8960 3.4807 4.3869 0.0313

t-value -3.66 -3.53 4.74 -4.64

ALR

Oct 1, 1990

Estimate -23.8206 -30.0966 -24.7723 -0.0982

Std Error 3.0587 3.6710 4.6174 0.0228

t-value -7.79 -8.20 -5.36 -4.31

Trend Term Estimate 1.2147 1.4041 2.8777

Std Error 0.3934 0.4737 0.6187

t-value 3.09 2.96 4.65

Note: Bold italics indicates statistically significant reduction (á=0.05, one-tailed test, t = -1.645)

The effective dates for Florida’s laws were: ALR on October 1, 1990, and 0.08 on January 1,

1994, leaving only 2 years of data (24 data points) for analysis during the post-0.08 time frame. 

A review of the graphs for the State of Florida indicates the presence of an increasing trend during

the period 1982 through mid-1989. Long-term trends were included in each of the statistical

models, and were found to be statistically significant (t = + 1.96, á = 0.05, two-tailed test) and

greater than zero, confirming the presence of the baseline upward trend. The October 1990

implementation of the ALR law is associated with statistically significant reductions in both highBAC fatalities and alcohol-related fatalities (BAC > 0.01), as well as a significant reduction in

sober fatalities (although there is no reason to believe this was causally related). A similar pattern

was observed for the January 1994 implementation of the 0.08 law, with significant reductions in

both high-BAC and alcohol-related fatalities. During this time frame, sober fatalities, which began

increasing about mid-1992, continued to increase to the point where they exceeded their level

during any time since the beginning of the 1982 baseline period. The ratio of high-BAC to sober

fatalities experienced statistically significant declines associated with both the October 1990 ALR

law implementation and the January 1994 BAC 0.08 law implementation. A trend term estimated

in the ratio series failed to reach statistical significance (t = -0.0038) and was, therefore, dropped

from the model.
The Effects of 0.08 Laws -25-

Exhibit 16

New Hampshire

BAC Level Ratio

> 0.10 > 0.01 0.00 > 0.10/0.00

0.08

Jan 1, 1994

Estimate 0.2937 0.5256 -0.7659 0.1597

Std Error 0.9232 1.1252 0.9716 0.3692

t-value 0.32 0.47 -0.79 0.43

ALR

Jul 13, 1992

Estimate -2.8392 -3.4313 0.0185 0.3160

Std Error 0.767 1.0573 0.7886 0.2861

t-value -3.70 -3.25 0.02 1.10

Note: Bold italics indicates statistically significant reduction (á=0.05, one-tailed test, t = -1.645)

The ALR law was implemented in the State of New Hampshire on July 13, 1992; 0.08 BAC

became effective on January 1, 1994. Being a small state, New Hampshire’s monthly fatalities

occur with relatively low frequency, and the timing of the two laws leaves 24 months of 0.08

BAC law experience upon which to base an assessment. From all indications, none of the data

series exhibited statistically significant declines during the 0.08 BAC time period. ALR, which

became effective in July 1992, was associated with statistically significant decreases in high-BAC

and alcohol-related fatalities. However, a review of the graph suggests that both series began

their declines around January 1992, seven months before the law became effective. At the same

time, the ratio of high-BAC to sober fatalities appears to have begun its decline even earlier, in the

fall of 1991, almost one year before ALR became effective.
The Effects of 0.08 Laws -26-

Exhibit 17

New Mexico

BAC Level Ratio

> 0.10 > 0.01 0.00 > 0.10/0.00

0.08

Jan 1, 1994

Estimate -1.6780 -1.4533 2.9498 -0.3636

Std Error 1.6046 1.8216 1.1475 0.0976

t-value -1.05 -0.80 2.57 -3.72

ALR

Jul 1, 1984

Estimate 0.8070 1.0169 -0.9824 -0.0586

Std Error 1.5626 1.7782 1.0520 0.0897

t-value 0.52 0.57 -0.93 -0.65

Trend Term Estimate -0.5327 -0.6967

Std Error 0.1836 0.2153

t-value -2.90 -3.24

Note: Bold italics indicates statistically significant reduction (á=0.05, one-tailed test, t = -1.645)

New Mexico’s ALR law became effective on July 1, 1984 and the 0.08 BAC law took effect on

January 1, 1994. Reviewing the graphs for alcohol-related and high-BAC fatalities suggests the

presences of a long-term trend during the 1982 through 1993 time frame, and thus, terms

representing this trend were included in each of the statistical models. Significant trend terms

were found for both the alcohol series, while neither the sober fatality nor ratio series yielded

statistically significant trends, and thus, were dropped from the models. While the estimated

change in high-BAC fatalities (-2.2826 per month) was found to be statistically significant, a

review of the graph suggests that this is almost invariably due to the drop in high-BAC fatalities

that began in mid-1990, six years after the ALR law took effect. Alcohol-related fatalities show a

very similar pattern, although the estimate (-2.4005) just failed to reach statistical significance (tvalue of -1.59 vs. the critical value of -1.645). In any case, the ratio of high-BAC to sober

fatalities does not demonstrate a statistically significant reduction associated with ALR. On the

other hand, the 0.08 BAC law, which was effective in January 1994 (leaving 24 months of post0.08 experience for analysis) is associated with statistically significant reductions in high-BAC

fatalities, alcohol-related fatalities, and the ratio of high-BAC to sober fatalities. Inspection of the

graphs of these series indicate the drop beginning in January 1994 was relatively easy to see. A

trend term, added to the statistical model for the high-BAC to sober fatality series failed to reach

statistical significance (t-value of -1.54 vs. the critical value of -1.645) and was dropped from the

model. However, even the model containing this term yielded a statistically significant decline for

0.08 (t-value of -1.92).
The Effects of 0.08 Laws -27-

Exhibit 18

Virginia

BAC Level Ratio

> 0.10 > 0.01 0.00 > 0.10/0.00

0.08

Jul 1, 1994

Estimate -3.0888 -4.1830 6.7277 -0.1336

Std Error 3.4273 4.4738 3.7646 0.0896

t-value -0.90 -0.93 1.79 -1.49

ALR

Jan 1, 1995

Estimate -2.1217 -1.3853 -4.4790 0.0083

Std Error 3.7400 4.8893 4.1694 0.0998

t-value -0.57 -0.28 -1.07 0.08

Note: Bold italics indicates statistically significant reduction (á=0.05, one-tailed test, t = -1.645)

The 0.08 BAC law became effective in the State of Virginia in July 1994. This was followed by

implementation of the administrative license revocation law, six months later, in January 1995. 

Being so close to the end of the time period under study, there was only 12-18 months of data to

study the impact of these laws. None of the alcohol fatality series (high-BAC, alcohol-related

fatalities and the ratio) exhibited statistically significant reductions associated with either of these

laws. However, as stated earlier, when two interventions occur in such close temporal proximity,

it is essentially impossible to estimate the separate impacts of each. Therefore, as was done

previously, a supplemental analysis was conducted, using a single intervention variable, beginning

in July 1994, to represent the combined impact of both 0.08 and ALR. The results are presented

below.

Exhibit 18a

Virginia – Supplemental Analysis of Combined 0.08 & ALR Intervention

BAC Level Ratio

> 0.10 > 0.01 0.00 > 0.10/0.00

Combined

Effect of

0.08 & ALR

Jul 1, 1994

Estimate -4.5637 -5.1332 3.6260 -0.1273

Std Error 2.2928 3.0193 2.4907 0.0588

t-value -1.99 -1.70 1.46 -2.17

Note: Bold italics indicates statistically significant reduction (á=0.05, one-tailed test, t = -1.645)
The Effects of 0.08 Laws -28-

The analysis of the combined effect of Virginia’s 0.08 and ALR implementation shows that highBAC and alcohol-related fatalities were significantly fewer for the period July 1994 through

December 1995, compared with 1982 through June 1994. However, inspection of the graph of

these data indicates that the reductions in high-BAC and alcohol-related fatalities began at the

start of 1991, three and one-half years prior to implementation of these laws. These alcohol

fatalities appeared to reach a new level in 1992, and remained at this level throughout the period

under study (December 1995). No noticeable decline occurred in these alcohol-related fatalities

after July 1994. In contrast to these data, the high-BAC to sober fatality ratio appears to have

declined beginning around September 1994, about midway between the implementation of these

two laws. This is likely associated with the increase in sober fatalities that began just after 0.08

implementation (July 1994), leading to a decline in the ratio.

Discussion of Fatality Analyses

Exhibit 19

Effects of 0.08 BAC Laws on High-BAC (BAC $.10) Fatalities, 

Alcohol-Related Fatalities (BAC >0.01) and the Ratio of High-BAC to Sober Fatalities

BAC Level

State Effective

Date

0.10+

Fatalities

0.01+

Fatalities

Ratio

High-BAC / Sober

Utah * Aug 1983 N N N

Oregon * Oct 1983 N N N

Maine Aug 1988 N N N

California * Jan 1990 N N N

Vermont Jul 1991 Y Y Y

Kansas Jul 1993 N N Y

North Carolina Oct 1993 N N Y

Florida Jan 1994 Y Y Y

New Hampshire Jan 1994 N N N

New Mexico Jan 1994 N N Y

Virginia * Jul 1994 N N N

Significant

Reductions

2

States

2

States

5

States

Notes: * Administrative License Revocation and 0.08 Laws passed within one year of each other.

Y in bold italics indicates statistically significant reduction.

California and Virginia experienced significant declines with 0.08 & ALR were treated as a single factor.
The Effects of 0.08 Laws -29-

Evaluating social science interventions, where the ability to “control” the characteristics of the

treatment (or intervention) applied is a complex process. The mere passage or implementation of

a law or policy may be marked by only a point in time, or it may be accompanied by various levels

of public information and education campaigns. In addition, implementation of such a law or

policy may be linked to the opportunity to publicize other countermeasure areas, such as

enforcement, drawing the public’s attention to the fact that their risk of detection, apprehension

and conviction for drinking and driving may be greater now than it used to be. The new law may

make it possible to apply other sanctions, such as administrative license revocation, to a broader

category of offender, who previously had not been eligible for such a sanction. All of these

possibilities, and others, may be applied in varying degrees from state to state, making it that

much more difficult to draw comparisons from the implementation of what appears to be a simple,

uniformly defined law or policy. BAC 0.08 laws are no different; neither are administrative

license revocation laws. The definition of each of these laws can be described briefly and in very

simple terms. Their actual implementation, however, can vary greatly from state to state, and

possibly even among jurisdictions within the state. Both of these laws are likely to have been

implemented in differing ways among the states, with differing degrees of enforcement and public

information. It is not always a matter of better or worse, but rather different, as differing policies

and needs exist among the various municipalities. Thus, it is not surprising when such laws and

policies yield mixed results, both over time, and across political jurisdictions. 

The early experiences with 0.08 BAC laws (the States of Utah and Oregon, both became effective

in 1983) did not demonstrate statistically significant reductions in the either the raw numbers of

high-BAC or alcohol-related fatalities, nor the rate of alcohol-involved fatalities (as evidenced by

the ratio of high-BAC to sober fatalities). At the time of their 0.08 implementation, neither state

had an ALR law on the books. Utah implemented ALR at the same time as their 0.08 law

(August 1983), while Oregon implemented ALR 10 months after its 0.08 effective date (July

1984); Oregon’s ALR law was found to be associated with a statistically significant reduction in

alcohol-related fatalities as well as the ratio of high-BAC to sober fatalities.

After a 5 year hiatus, Maine became the third state to implement a 0.08 BAC law, in August

1988. Maine experienced fewer high-BAC and alcohol-related fatalities, as well as a lower rate of

alcohol involvement after 0.08 implementation, compared to the prior period. Visual inspection

of the above graph indicates that the high-BAC to sober fatality ratio had already begun to decline

as early as mid-1985, three years prior to 0.08 implementation, making it difficult to attribute

reductions to 0.08. At the same time, Maine had already implemented its ALR law in January

1984. Long-term trend factors, included in the Maine analyses, were found to be statistically

significant for all of the alcohol-related series (high-BAC, any alcohol, and the ratio), leaving the

observed reductions associated with both 0.08 and ALR to be not statistically significant. Thus,

while there was apparently no immediate impact of Maine’s ALR law, it would be worthwhile to

investigate whether enforcement or administrative policies were changed during the mid-1985

time frame, that would point to a possible delayed effect of ALR on fatal crash alcohol

involvement. This type of investigation was beyond the scope of the present study.

With the onset of the 1990's the pace of 0.08 implementation sped up. The next state to

implement 0.08, California, experienced declines in both high-BAC and alcohol-related fatalities. 
The Effects of 0.08 Laws -30-

However, the rate of alcohol involvement remained essentially unchanged for approximately 12

months after implementation of 0.08 (and six months after ALR). Whether this “delayed effect”

was due to a maturation of these policies or changes in enforcement or other countermeasure

areas is beyond the scope of this study. However, there is no question that the rate of alcohol

involvement and the numbers of high-BAC and alcohol-related fatalities have declined

dramatically in the State of California, and have continued to remain at these lower levels,

especially after implementation of ALR. As demonstrated in the previous section, when the two

laws (implemented only six months apart) are treated as a single intervention, a statistically

significant reduction results, with the major portion of the reduction still occurring 12 months

after the 0.08 effective date.

Vermont was the next state to implement a 0.08 BAC law. While fatalities in the State of

Vermont occur with very low frequency, leading to relatively wild swings, the analysis indicates

that both alcohol-related fatality series, as well as the high-BAC to sober fatality ratio experienced

statistically significant reductions after the implementation of 0.08. It is also clear that the rate of

alcohol involvement had not been declining prior to 0.08 implementation (the estimate for longterm trend was small and not approaching statistical significance), and thus, these reductions

cannot be considered a continuation of an already existing downward trend. At the time of 0.08

implementation, ALR had been in effect since December 1989.

The next six states to implement 0.08 BAC laws did so over a relatively short period of time (the

13 months from July 1993 through July 1994). Four of these six states are associated with

significant reductions in the rate of alcohol involvement, (five, if the combined effect of 0.08 and

ALR in Virginia is considered), although at least some of these states may have implemented their

law in the midst of an existing downward trend in the alcohol involvement rate (North Carolina,

Florida and New Mexico).

In the State of Kansas, neither high-BAC fatalities nor alcohol-related fatalities exhibited

statistically significant reductions associated with 0.08 implementation. Both alcohol measures

appeared to have peaked in early 1991 and began a decline about two years prior to the effective

date of the 0.08 BAC law. In Kansas, non-alcohol-related fatalities increased relatively

dramatically around the time of the 0.08 BAC law, leading to decline in the rate of alcohol

involvement; although this decline appears to have also begun as early as 1991.

North Carolina’s implementation of 0.08 appears to have occurred in the presence of an already

existing downward trend in both alcohol fatality measures and the rate of alcohol involvement, all

of which appeared to begin in early 1992, about 18 months prior to 0.08 implementation. While

the statistical models, which compare the October 1993 through December 1995 period to the

11+ prior years of data, demonstrate statistical significance, it is difficult to attribute all of this

reduction, in a causal way, to 0.08 implementation. Statistically significant long-term trends are

apparent in the high-BAC and alcohol-related fatality series, yielding nonsignificant reductions in

the raw numbers of fatalities. In contrast, the significant reduction in the rate of alcohol-involved

fatalities, even after accounting for the significant long-term trend, is evidence of at least some

impact being associated with 0.08 BAC laws.
The Effects of 0.08 Laws -31-

The experience in the State of Florida is very similar to that in North Carolina, wherein the rate of

alcohol involvement appears to have been declining beginning in early 1992, but also continued to

decline, reaching new lows after the implementation of 0.08 in January 1994. Florida also

experienced significant reductions in both alcohol-related fatality measures, while at the same time

experienced dramatic growth in non-alcohol-related fatalities beginning in January 1992.

New Hampshire exhibited no impact in any of its measures associated with the January 1994

implementation of its 0.08 BAC law. However, the July 1992 implementation of ALR was

associated with statistically significant reductions in high-BAC and alcohol-related fatalities; no

significant change in the rate of alcohol involvement was found.

After the January 1994 implementation of its 0.08 law, New Mexico experienced a significant

reduction in the rate of alcohol involvement. Significant downward trends were found in the

high-BAC and alcohol-related fatality series, leaving 0.08 associated with nonsignificant

reductions in the raw numbers of alcohol-related fatalities.

Lastly, the State of Virginia implemented 0.08 in July 1994, leaving only 18 months of data for

analysis in this study. None of the alcohol measures in Virginia showed statistically significant

reductions during the six months after 0.08, but prior to ALR implementation. However, the

State of Virginia did experience significant declines after the January 1995 implementation of

ALR.

A clear effect of 0.08 legislation is in reducing beer consumption. In four of the five states

(California, Maine, Utah and Vermont) for which sufficient beer consumption data were obtained,

annual consumption trends indicate decreases associated with implementation of a 0.08 law. The

association, however, was strong in only two of the four states (California and Vermont). The

absence of a decrease in the fifth state, Oregon, may be due to a large decrease in beer

consumption that occurred earlier, making it difficult for a further decline to occur when the 0.08

law was passed.

In summary, the analysis of the impact of 0.08 BAC laws found that 5 of the 11 states that

implemented such laws experienced significantly lower rates of alcohol involvement among

fatalities, and that 2 of these states experienced significantly fewer high-BAC and alcohol-related

fatalities during the period after implementation. Four of these states (Maine, North Carolina,

Florida, and New Mexico) were apparently already experiencing a downward trend in alcohol

involvement, due possibly to other factors such as the presence of laws (ALR), the use of sobriety

checkpoints, or a general societal trend for reduced alcohol consumption. Two additional states

of the 11 (California and Virginia) experienced statistically significant reductions in the rate of

alcohol involvement among fatalities when the 0.08 and ALR laws, which became effective within

about 6 months of one another, were modeled as a single intervention.

Each and every state in the group exhibiting a significant association between 0.08 and reductions

in alcohol involvement either already had an administrative license revocation law in effect

(Vermont, Kansas, North Carolina, Florida and New Mexico), or that reductions did not occur

until after ALR was in place (California and Virginia). Clearly, other factors may be at work, as
The Effects of 0.08 Laws -32-

evidenced by the presence of declines in alcohol involvement that began around 1992, which

coincided with the implementation of neither 0.08 nor ALR. While it is difficult to pinpoint

exactly what factors may be responsible, the data and analyses are clearly suggestive that 0.08

BAC laws have some deterrent effect, leading to reductions in drinking and driving, most notably

in conjunction with the presence of other drunk-driving laws and practices, especially

administrative license revocation.

Does merely changing the definition of the legal blood alcohol concentration driving limit result in

significant reductions? It is hypothesized that implementing a 0.08 BAC law has a synergistic

effect on the other components of the anti-drunk driving system, namely the enforcement,

adjudication, judicial, licensing, and public information / education components. It is strongly

suggested that combating drunk driving is most effective when ALL of the components are at

play, in the same vein as the approach espoused by the U.S. Department of Transportation’s $88

million Alcohol Safety Action Projects of the 1970's and 1980's, which emphasized the systems

approach to addressing this societal problem. Implementing 0.08 BAC laws and the publicity

surrounding them serves to remind the public about the dangers of drinking and driving, and may

catalyze the enforcement, judicial and licensing communities to refocus its efforts and draw

renewed attention to the importance of removing drunk drivers from the nation’s roads.
The Effects of 0.08 Laws -33-

Exhibit 20

Effects of ALR Laws on High-BAC (BAC $.10) Fatalities, 

Alcohol-Related Fatalities (BAC >0.00) and the Ratio of High-BAC to Sober Fatalities

BAC Level

State Effective

Date

0.10+

Fatalities

0.01+

Fatalities

Ratio

High-BAC / Sober

Utah * Aug 1983 N N N

North Carolina Oct 1983 N N Y

Maine Jan 1984 N N N

Oregon * Jul 1984 Y Y Y

New Mexico Jul 1984 N N N

Kansas Jul 1988 N Y N

Vermont Dec 1989 N N N

California * Jul 1990 Y Y N

Florida Oct 1990 Y Y Y

New Hampshire Jul 1992 Y Y N

Virginia * Jan 1995 N N N

Significant

Reductions

4

States

5

States

3

States

Note: * Administrative License Revocation and 0.08 Laws passed within one year of each other.

Y in bold italics indicates statistically significant reduction.

California and Virginia experienced significant declines when 0.08 & ALR were treated as a single factor.
The Effects of 0.08 Laws -34-

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