Mandating drunk-driving charges against young drivers with any detectable amount of alcohol in their bodies has had no effect on the number of alcohol-related crashes or fatalities in the states where they have been implemented, according to a new study from a Sam Houston State University economics expert.

WBTX-TV reported April 24 that economics professor Darren Grant drew his conclusions from an analysis of 30,000 fatalities in nighttime crashes involving drivers under age 21, comparing data from states with zero-tolerance laws to those without such laws.

"If you look at the total number of accidents or the types of drinkers involved in these accidents, they just aren't affected," said Grant. "Other factors matter, but not these laws."

Grant said the flaw in the law is that it doesn't make the penalty for drunk driving harsher per se: "It is just harder to satisfy the law. Drivers now have to give up drinking all together. It's more exacting in that sense."

"Because you must sacrifice more to comply with the law, we should expect two responses: some people will comply and drink less, but others will just give up trying to satisfy the law and drink more, Grant said. "So we should not assume a zero-tolerance law will inevitably reduce drunk driving."

In fact, Grant found no change in the number of heavy drinkers or nondrinkers in the states with zero-tolerance laws. "Instead, among drivers involved in traffic accidents, there is the same fraction of heavy drinkers, the same fraction of mild drinkers, the same fraction of nondrinkers," he said. "It's just not changing."

The study, "Dead on Arrival: Zero Tolerance Laws Don't Work," will be published in the journal Economic Inquiry.