Can a Person Be Convicted of Drunk Driving if His BA Is Below .08%?

Drivers in Kootenai County and elsewhere in Idaho can be prosecuted if they drive while legally impaired, either from alcohol or drugs (even drugs prescribed by a physician).

With regard to alcohol, there is a specific Idaho statute which makes it illegal to drive with a blood alcohol level blood concentration greater than .08%. The law was previously .1% and, years ago, some states allowed a blood alcohol level of .15%.

States have gradually been reducing the level of illegal alcohol level based upon a large number of scientific studies. These studies demonstrate that all drivers become legally impaired at some point between .06 and .08. For this reason alone, a driver with a blood alcohol level could be prosecuted if the arresting officer’s field sobriety tests demonstrate that the driver was too impaired to drive, even if his BA level was .07%.

Typically, the investigating officer will perform the following tests at the scene, after a suspect driver has been pulled over:

  • The line walk test (asking the person to walk 10 steps, heel to toe, in a straight line.
  • The leg lift test (asking the person to lift one leg off the ground and to keep it there for a segment of time).
  • The finger to nose test (the driver is asked to close his eyes, lean his head back, and have his arms extended and then touch the tip of his nose with a single finger from each arm).
  • The Horizontal Gaze Nystagmus test – see

If the driver performs poorly on these tests, he can be prosecuted for DUI even though his blood level was not .08% or above. Other factors leading to an arrest are whether the person has a flushed face, slurs his speech or has bloodshot eyes.

The second reason a person with a blood alcohol level below .08% can be prosecuted is because the statute refers to the impairment while driving. For example, if a person is asleep in his car, parked by the side of the road, it may have been several hours since he was driving his car. Because the human body continually metabolizes alcohol during and after drinking, the driver’s blood alcohol may have been at an illegal level several hours ago when he was driving, even though his alcohol level is legal after he has had a few hours sleep by the side of the road.

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