During the process of burning fat, the liver produces toxic byproducts called “ketones.” Ketones are chemically similar to the isopropyl alcohol found in solvents such as acetone.
Some of these ketones are excreted in the breath. Unfortunately, in many states, breath testing devices can be tricked by ketones. This is because they don’t always reliably distinguish isopropyl alcohol from ethyl alcohol, the type found in alcoholic drinks. This can lead to a falsely high BAC reading on a DUI breath test.
Breath that smells like alcohol.
Example: Les was stopped at a DUI sobriety checkpoint. An officer noticed that Leo’s eyes were red and that Leo seemed confused. Leo performed poorly on FSTs, and a preliminary breath test showed his BAC at .10%. Leo was arrested under suspicion of DUI. After Leo was arrested, he chose to take a DUI blood test at the station, rather than another breath test. The blood test showed Leo’s BAC to be just .05. It turned out that Leo had been working on a project on his computer for the better part of three days straight. During that time he had eaten almost nothing. When the project was finally finished, he had a beer to celebrate.