Is There Really That Big of a Difference between .05 and .08 BAC?

By February 10, 2017Thomas Law Firm

In Colorado, driving with a BAC of .08 is illegal and can net you a DUI charge. Driving with a BAC of .05 can get you a lesser charge of DWAI (driving while ability impaired). But what the distinction? Is a BAC of .05 really that different from a .08? What’s the science behind these two numbers?

The Science of Booze in the Blood

Using the standard definition of one drink (that being 12 ounces of 5 percent alcohol beer, five ounces of 12 percent alcohol wine or one and a half ounces of 80 proof liquor), in the average person, about three beers will bring BAC up to .05. The Centers for Disease Control and Prevention (CDC) say that at .05, drivers have reduced coordination and ability to track moving objects as well as a harder time steering.

One more beer would take a person’s BAC up to .08. At .08, drivers have trouble controlling their speed as well as difficulty processing information and reasoning. Balance, vision and reaction time are often affected at this level, making it difficult to notice roadway dangers.

Beyond .08, drivers have a clear loss of reaction time and control as well as difficulty staying in their lane and braking appropriately.

Studies dating back to the 1960s suggest that drivers with .05 BAC levels have a relative crash risk of 1.38 compared to sober drivers. At .08, that risk jumps to 2.69. At .10? A whopping five times relative crash risk.

Because .05 BAC does suggest impairment, Colorado has the lesser DWAI charge to keep these mildly impaired drivers off the roads. Someday, we could see the law change such that .05 BAC will become the new threshold for DUI charges as well. Some countries like France, Germany and Australia already have, and in 2013, the National Transportation Safety Board suggested that the U.S. do the same.

Our DUI defense attorneys are dedicated to helping those charged with drunk driving in Colorado.

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