Why Will Universal Interlocks Be Set Below .08 BAC?

The BAC threshold for a driver to be considered legally “drunk” is already quite low. By 2005 every state in the U.S. had lowered its legal limit from 0.10 to 0.08 percent—even though drivers talking on a hands-free cell phone make more driving errors and have longer reaction times than drivers who are legally “drunk” at 0.08 BAC. (In fact, the average BAC in 2005 of a driver involved a fatal accident was 0.17—more that twice the current legal limit.)

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Number of drinks*:	1 2 3 4 5 6 7 8 9 10	?
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* A “standard” drink in the U.S. is defined as a 5 oz glass of wine, a 12 oz beer, and a mixed drink with 1.5 oz of spirits. Because of variance in proof (alcohol per volume), these three different servings all contain the same amount of alcohol: 17 grams.

At less than 0.08 percent most people don’t exhibit any signs of intoxication. But under “presumptive” laws in almost half of the states, drivers can be arrested for driving while “impaired” with BAC levels as low as 0.02 percent.

Since car manufacturers build vehicles that may be driven in all 50 states, the lowest threshold for interlocks would trump the higher BAC limits. Interlocks would have to be set based on the lowest BAC threshold. With a give-or-take 0.02 BAC margin of error built into interlock technology, these devices would effectively establish zero-tolerance.

After interlocks become universal, the debate over BAC limits would be moot. Technology -- not democracy -- would decide.

The hidden agenda behind universal interlocks is not to eliminate drunk driving, but to end any drinking before driving. This intrusive technology would treat a couple who enjoyed wine with dinner the same as an alcoholic who just finished his eighth drink. Right now the law recognizes the difference, but soon your car may not.