How Many Drinks Is Too Many To Drive?

Posted on May 2, 2011   |   by Lundin Law PLLC

Clients often ask us, “How much is too much to drink before getting behind the wheel?” Unfortunately, our answer is always “It’s complicated.”

The simple answer is that “too much” is the amount that causes a breath test reading of .08 or more within two hours of driving. This is the clear cut standard set by law under RCW 46.61.502.

But how is a driver to determine whether he or she is .08 or higher before driving? The fact is that there is no practical way to make this determination with precision. Although you might recall hearing a “One Drink Per Hour” rule, and the liquor control board publishes charts that are helpful, there are so many variables (biological, instrumental, etc) involved that the rule or chart is at best only an estimation.  Even if the chart was 100% accurate in a given case, simply having a reading under .08 is no guarantee that that a DUI arrest and prosecution cannot occur because the officer can arrest and charge in such a case if he is of the opinion that the suspect’s ability to drive was impaired in any appreciable degree.

Another difficulty in determining whether it is “safe to drive” is that there is tremendous variability regarding what constitutes a “drink” depending upon who mixed the drink and further, there is variability in the amount of alcohol in certain similar-sounding drinks. For example, a glass of beer might have 5.6% alcohol (Anchor Porter) or 2.5% alcohol (Pabst Extra Light) depending upon the brand/type. In the example above, two glasses of Anchor Porter would have approximately the same alcohol content as four glasses of Pabst Extra Light, but there are not many people who make this type of calculation when they are out on the town.

It is possible to reasonably estimate the alcohol level in one’s blood using a time-tested formula known as Widmark’s formula. This formula is used in DUI trials to calculate a breath alcohol level based upon percentage of alcohol in the drink, number of drinks, time of consumption, sex, weight and other factors. Although this formula is accepted evidence in DUI trials, as a practical matter it is of little use to the driver who wonders whether he/she is safe to be on the road.

The best advice, as always, is that if you are going to drive, don’t have anything to drink at all. The next best options is to have designated driver provide transportation. That is the only sure way to avoid problems given the severe penalties in Washington State’s DUI laws.