Current interlock technology

Current Interlocks

Ignition interlocks are in-car breathalyzers that measure a driver’s blood alcohol concentration (BAC). They prohibit the engine from starting if a breath sample registers above a pre-set level, typically around 0.02 BAC.

Government statistics show that drivers who cause the majority of alcohol-related fatalities have incredibly high BACs—twice the legal limit in most cases. In-car breathalyzer technology was developed to keep these chronic alcohol abusers off the road.

But instead of using the technology to punish the worst offenders, activists are lobbying state governments to require the devices for low-BAC (blood alcohol concentration), first-time offenders.

The problem is that laws mandating ignition interlocks for all offenders deny judges the ability to distinguish between a driver one sip over the limit and high-BAC, repeat offenders.

That’s why 27 states have passed interlock mandates for high-BAC (.15 and higher) and repeat-offenders, while just 11 states target low-BAC, first-time offenders. Learn about state laws here.

Low-BAC, first-offender mandates are the first step in getting the public to accept mandatory interlocks in all cars.[1]

Once the devices become mandatory in all cars, they will be set at low enough levels to prevent all moderate, responsible drinking prior to driving. Why such low levels?

Next step: Find out the difference between First Offenders and the Worst Offenders.


  1. Toward a Global Vaccine for Drunk Driving, 9th International Alcohol Interlock Symposium, pages 13-14

Did you know?

Did you know that Congress Might Pass an Interlock Mandate?

The Highway Bill, which is currently being debated in Congress, contains an extreme ignition interlock mandate that would force every state to punish all first-time DUI offenders with an in-car breathalyzer, even if they were just one sip over the legal limit.

Find out why that is the wrong way to fight drunk driving.