I don’t think I have ever seen a DUI police report where the arresting officer didn’t smell alcohol on the person’s breath. This was even true when the person was found to be under the legal limit. Nor do I think that I will ever see a DUI police report where the arresting officer doesn’t smell alcohol on the DUI suspect’s breath.
Whether the person has been drinking or not, the officer’s observation of alcohol smell is extremely damaging.
Does the smell of alcohol necessarily mean that a person has been driving under the influence? Absolutely not.
Alcohol, itself, has little or no odor. Rather, what is being smelled are the other ingredients in any particular alcohol. Take for example non-alcoholic beer. Both non-alcoholic beer and alcoholic beer are made from grains, malts, hops, and yeast. A person who has consumed three non-alcoholic beers will smell substantially similar to someone has consumed three alcoholic beers, yet the person who consumed the non-alcoholic beers will have little to no alcohol in their system.
Even if the person had been drinking, the strength of the smell of alcohol does not necessarily correlate to the level of intoxication. For example, beer and wine produce the strongest “odor of alcohol” when, in fact, they contain less alcohol than nearly all spirits. Yet in most DUI police reports, the strength of the smell of alcohol almost always correlates to how intoxicated the arresting officer perceives the driver. In other words, when the officer observes a “strong odor of alcohol,” they almost always perceive the driver to be heavily intoxicated. Again, I have found this “correlation” to be present even when it was later determined that the driver was actually under the legal limit.
A 1999 study found that officer estimates of blood alcohol levels based on smell were no more accurate than random guesses.
This is a little disturbing, to say the least, given that odor on the breath is one of the main “pieces of evidence” of intoxication for police and prosecutors in DUI cases.