Many people think that their tolerance for alcohol—or lack thereof—may have some impact on an operating while intoxicated trial. This idea is misguided, as any alcohol tolerance or intolerance has no bearing whatsoever on an OWI trial.
A state prosecutor may prove a defendant’s guilt of operating while intoxicated in one of two ways: OUIL or UBAL.
OUIL, which stands for operating under the influence of liquor, is the common law theory of OWI. When operating under this theory, the state is trying to show that your ability to safely drive a vehicle was substantially lessened due to the consumption of alcohol or a controlled substance. To prove this, the prosecution will generally use witnesses to testify that you were, in fact, drunk.
UBAL—short for unlawful blood alcohol level—is the statutory theory of OWI. To prove OWI under this theory, all the prosecution must do is demonstrate that a chemical test reliably and accurately showed your BAC to be .08% or higher at the time you were pulled over.
If the state is operating under the UBAL theory, then alcohol tolerance is completely irrelevant to the case. In this situation, the prosecution does not need to demonstrate that your ability to safely operate the vehicle was impaired. Because Michigan state law says that it is unlawful to operate with a BAC of .08% or above, the prosecution will simply rely on evidence related to your blood alcohol content.
When arguing the OUIL theory, the state will generally rely on testimony from witnesses—specifically, the arresting officer who can attest to the results of any field sobriety tests you took. If the officer testifies that you passed the field sobriety tests, then your ability to safely operate the vehicle may not have been substantially impaired, regardless of whether you have a tolerance for alcohol or not.