Impaired Driving: What is too much?

How many times have you heard someone say, “It’s okay to drive impaired, as long as you’re not too impaired.” When it comes to mixing alcohol—or drugs—and driving, this message has been implied and reinforced for generations.

It’s hard to believe that the first legal Blood Alcohol Concentration (BAC) was set at .15 in the 1930s. In the 50s and 60s, states gradually lowered the legal limit to .10. It wasn’t until 2004 that all states adopted the current .08 as the legal limit for impaired driving offences. A BAC of .08 or above is now widely accepted by many as being too impaired for safe driving. Reaction time, vehicle control, divided attention, vigilance to the driving task, decision making, and controlling speed are all impaired at .08. At .05 most of them are. The fact is that when it comes to driving there appears to be no safe BAC. In fact, you may be prosecuted for alcohol impaired driving even when your BAC is well below the legal standard of .08. This often comes as a big surprise to those convicted for DUI.

Initial levels of impairment are reflected in judgement, and specifically in one’s ability to accurately assess one’s level of impairment. Unfortunately, this is when we have expected people to take responsibility for deciding whether or not they should be driving. Often, the question people ask themselves is am I too impaired to drive when the question should be have I been drinking.
The National Transportation and Safety Board is convinced that lowering the legal limit again would reduce the number of fatal accidents and wants states to lower the legal limit to .05 or lower. This would bring the U.S. into alignment with much of the rest of the world and essentially move the bar for arrest to detectable levels of alcohol when one is operating a motor vehicle. The message here is clear: Impairment begins with the first drink: The only safe driver is one with zero BAC.

As medical and recreational marijuana has become legal in many states, it appears that we are poised to make similar missteps in determining impairment levels for marijuana use. From my experience as a substance use counselor, it seems that for many people the risk for future impaired driving actually rises with the medicinal marijuana card, as it will with marijuana legalization—especially when folks tend to believe that legalization gives them license to drive while using marijuana. This belief system is currently quite prevalent, and most likely, commercialization will reinforce it.

It’s unclear how difficult it will be to get arrested for marijuana impaired driving in the coming months and years, but given the current climate in law enforcement, my guess is that it will become much easier and more common (as it has in other states). Most likely, the question of impairment level for marijuana will be decided by the legislature, law enforcement, and the courts.

So, as we enter a season of celebrations which often include alcohol, perhaps the most important question to consider before getting behind the wheel of a vehicle is not how impaired are we, but have we been using alcohol or other drugs. If so, please keep in mind some of the tried and true practices for celebrating sober. Appoint a designated driver before heading out to a social gathering. Make plans for public transportation to and from an event. Ask a friend to keep your keys if you are too impaired to drive. If you are hosting a gathering, be sure to include non-alcoholic beverages. Most important, stay safe during this season and throughout the year.

Kim Hubbard, LADC
Program Manager/Impaired Driver Programs
Howard Center