William B. Mange

Criminal Defense Lawyer in Austin, Texas

Criminal Law Blog

February 07, 2010

Your criminal defense lawyer should be able to take probable cause affidavits in DWI cases apart, piece by piece. The piece I want to take apart today is the part that says that the driver had a “strong,” “moderate,” or “faint” odor of alcohol on his breath.

If you’ve seen a probable cause affidavit, you’ve probably noticed that there are checkboxes for the officer to mark regarding the driver’s breath.

There is a paper entitled “Police officers’ detection of breath odors from alcohol ingestion” written by Herbert Moskowitz, Marcelline Burns, and Susan Ferguson. Marcelline Burns is the government’s “go to” gal in putting together scientific papers that favor the Standardized Field Sobriety Tests. If you want to read the paper, click here.

The abstract to the paper says “[e]stimate of BAC [Blood Alcohol Concentration] level failed to rise above random guesses. These results demonstrate that even under optimum laboratory conditions, breath odor detection is unreliable, which may account for the low detection rate found in roadside realistic conditions.

In the conclusion, the authors wrote: “[t]his laboratory situation created an optimum opportunity to use alcohol odor as a sole indication of the presence of alcohol and for estimation of its strength. Clearly, estimates of strength, even in this situation, were invalid as were identifications of the beverage consumed. Also, even these extremely experienced officers were capable of detecting the presence of alcohol relatively reliably only in the region of 0.08% and higher.” With regard to this last sentence, please remember that these tests were conducted under optimum laboratory conditions, not in the field. In other words, this study doesn’t prove how reliably even extremely experienced officers can detect the presence of alcohol by smelling a driver’s breath.

The conclusion also says: “[g]iven the difficulty of detecting the odor of alcohol under roadside conditions and the likelihood of underestimating BAC from the strength of the odor, it would seem prudent for an officer who detects any odor of alcohol on a drivers [sic] breath, (assuming that the driver hasn’t drunk in the last 15 or 20 min), to administer field sobriety tests or an alcohol breath sensor.”

If police officers read “it would seem prudent” to mean “you have grounds for reasonable suspicion that the driver has been driving while intoxicated,” then they are making a big mistake. When the officer detains someone, he has to have reasonable suspicion. To have a reasonable suspicion, there has to be a reason for that suspicion. It can’t be mere guess work. But that’s what the paper says detection of alcohol consumption by smelling the odor of an alcoholic beverage is: no better than a random guess.

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William B. Mange

Criminal Defense Lawyer in Austin, Texas

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