Tolerance is defined as the diminished effect of alcohol on a body. What happens is that if a person drinks large amounts of alcohol on a regular basis, their body will adapt to the presence of alcohol. It will have less of an effect in comparison with when they were a naïf with alcohol.
But in terms of impairment, which is the focus of this committee, you cannot get tolerance to all aspects of impairment. Certain very complex functions are required to operate a motor vehicle, and you cannot get tolerance to that. Tolerance is intoxicated practice. You have to experience the event in the presence of alcohol, and you can't get tolerant to responding to complex driving situations, such as driving on a busy road when someone jumps out in front of the car.
You cannot develop tolerance to everything.