Program Profile: Reducing Blood Alcohol Concentration (BAC) Limits for Motor Vehicle Operations (New Jersey)

This program comprises legislation that was passed to reduce alcohol-related crash fatalities by lowering the blood alcohol concentration limit for adult drivers from 0.10 to 0.08. The program is rated Ineffective. There was a statistically significant reduction in passenger fatalities per crash after the implementation of the legislation; however, there were no statistically significant impacts on driver fatalities per crash or total fatalities per crash.

An Ineffective rating implies that implementing the program is unlikely to result in the intended outcome(s).

Program Goals/Program Components

On August 1, 2002, a bill was introduced into the New Jersey Assembly that proposed reducing the blood alcohol concentration (BAC) level necessary to convict a person for driving under the influence (DUI), from 0.10 to 0.08. The goal of the legislation was to reduce alcohol-related crash fatalities by lowering the allowable BAC limit for adult drivers. The bill targets adults who intend to drive after consuming alcoholic beverages and seeks to reduce the fatalities of these drivers and their potential passengers.

An amended version of the bill, S492/921, was approved by the New Jersey Senate (37–1) and Assembly (61–8–5) and was signed by the governor 2 years later. The bill went into effect on January 30, 2004 (Chamlin 2017).

Program Theory

This legislation is rooted in the theory of deterrence. The theory assumes that drivers make a rational choice that considers the costs and benefits of driving a vehicle after consuming alcoholic beverages. Costs of driving drunk include the risks of crashing or being arrested and convicted for driving under the influence, but benefits can include avoiding transportation costs or avoiding the embarrassment of being too drunk to drive (Thurman, Jackson and Zhao 1993). The theory of deterrence suggests that people are deterred from committing a crime when punishment for that crime is swift, severe, or certain. By reducing the BAC limit for adult drivers from 0.10 to 0.08, the bill increased the certainty of punishment and therefore increased the costs of driving drunk. Following from this theory, crash fatalities from alcohol-related car crashes will then be reduced because drivers will be deterred from operating their vehicles after consumption of alcohol (Chamlin 2017).

Study

Chamlin (2017) conducted an interrupted time series analysis to determine the effect of the 2004 New Jersey BAC legislation on crash fatalities. The outcomes of interest were total crash fatalities, driver fatalities, and passenger fatalities. Data were collected every month from January 1998 to December 2011 (n = 168). These dates were selected to encompass the period of time before and after the law went into effect on January 30, 2004. The number of fatalities and vehicle crashes involving fatalities was obtained from Fatal Motor Vehicle Crash Yearly Reports, an annual report from the New Jersey State Police.

An autoregressive integrated moving average (ARIMA) analytic technique was used to determine the difference in crash fatalities pre- and post-intervention. An ARIMA model consists of 1) the “noise” component, and 2) the intervention component. The noise component uses information from previous observations of an outcome to model the variation within the outcome series. This is used to separate confounding influences from those that are associated with the intervention. Once this is achieved, the intervention component is added, which can then determine the impact on the outcomes that resulted directly from the intervention. The study authors did not conduct subgroup analyses.

These sources were used in the development of the program profile:

These sources were used in the development of the program profile: