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Q. What is the legal drinking limit for CDL drivers? I have a Class A, in the DMV manual it says that it is .04%. Does this only apply if you are operating a commericial vehicle? Or does it carry over to personally owned vehicles as well? I had an unreliable source say that they recently changed it to .02 for both CMV and POV's. Could you shed some light on these questions please?
Dear Juneau Resident,
I can shed some light on this and your instincts are on, in that your source is unreliable. The short answer is there is no ‘legal’ level of alcohol allowed. .04 for commercial vehicles and .08 for personal vehicles is the intoxicated ‘per se’ limit. That means any driver over those levels is considered illegally impaired. You can and people do get arrested below those limits.
Alcohol starts impairing a person, any person, with the very first mouthful and the point where the person is a danger to themselves and others can and often does come below the per se limit. It might be one beer for someone and substantially more for another person. The test is how that person is responding to the alcohol not the level a breath machine shows. Many of the drivers JPD has investigated for DWI are mixing alcohol with prescription or over the counter drugs. The alcohol level might be quite low but enough to make the drugs much more powerful. This could lead to substantial impairment of motor skills well below the per se limit.
People with low tolerance for alcohol will become visibility impaired at a lower consumption level than what you would see with a regular drinker. Women also will show impairment faster than a man of the same size and same tolerance because women have water as a larger percentage of their bodies than men.
The best practice is no driving after any drinking because anything beyond no alcohol is a roll of the dice. Designated drivers should have no alcohol. JPD officers have had to explain many times that selecting the least drunk person to drive is not appropriate planning. This generally happens right after the 'designated driver' gets arrested.