Author: Sasha Tanner
Does the ignition interlock device (IID) live up to its purpose? The short answer: yes. Stick around for more details where Zeithammer, Macinko, and Silver uncover the overall effectiveness of these devices.
Measuring IID’s Deterrent Effects
Since previous studies only cover interlock effectiveness from a panel of DWI offenders, the researchers want to test to see if ignition interlock devices truly stop impaired driving behaviors among the broader population. The study’s design was based on the discrete choice experimental model:
- Discrete choice experiment (DCE): stems from the economic utility theory; it is a form of econometric and behavioral analysis that looks at human decision-making processes by measuring the utility levels of product or choice alternatives
- Survey design and questions are usually based on hypothetical situations to predict future behaviors.
Covering the Bases: The 4 W’s
- Who ~ 583 adults (18+) from 46 states who have consumed alcohol at least once a week completed a 19-minute online survey
- Participants ranged from little to heavy alcohol consumption and convicted to non-convicted individuals
- What ~ Study participants were asked to answer whether they would drink and drive based on the severity of the law and if they had an IID for a certain amount of time
- When ~ The survey was open for the entire year of 2023
- Why ~ To understand whether IID can deter people from driving under the influence of alcohol before being convicted with a DWI
A Comparison Between Penalties and IID Deterrent Effects
Penalties for DWI were measured from low to high enforcement. Participants selected whether they would drink in drive in circumstances of lesser to severe punishments. Here is what the researchers found:
- Low Enforcement: 39% wouldn’t drink and drive under these terms
- Penalties include small fines ($400), no imprisonment, no conviction, etc.
- High Enforcement: 53% wouldn’t drink and drive under these terms
- Penalties include longer prison times and heftier fines
Simultaneously, the researchers wanted to know the impact of ignition interlock device penalties juxtaposed to other kinds:
- Interlock penalties (0-1 years) had a greater impact on deterring DUIs than did mandatory alcohol treatment (0-6 months)
- A year of interlocking had a greater deterrent effect than a fine of $400 and the same impact as higher police enforcement
In the end, IIDs could potentially deter DWI cases among a range of individuals as much as and even more so than penalties.
IID Benefits: Policy Implications
- Since this study includes people with different levels of alcohol consumption and whether they had previous convictions, it implies that the IID discourages the general population from drinking and driving, thus encouraging states without IID penalties to adopt this into practice.
- States without IID penalties can see that its implementation is just as effective as charging a $2,200 fine or issuing 10 days in jail, encouraging them to use IIDs to discourage people from drinking and driving.
- States with these penalties can broadcast this information to educate the citizens on its deterrent effects.
If you’re interested in digging deeper into the study methods and results, the link to the article is below!
Sources
- Friedel, J. E., Foreman, A. M., & Wirth, O. (2022). An introduction to “discrete choice experiments” for behavior analysts. Behavioural Processes, 198, Article 104628. https://doi.org/10.1016/j.beproc.2022.104628
- Zeithammer, R., Macinko, J., & Silver, D. (2025). Assessing the deterrent effects of ignition interlock devices. American Journal of Preventive Medicine, 68(1), 137–144. https://doi.org/10.1016/j.amepre.2024.09.009
