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Keto diet may cause breath test false positives

On Behalf of | May 14, 2019 | Drunk Driving |

An odd circumstance regarding the defendant’s diet got DUI charges dropped in a recent case. Readers in New Jersey might be interested in the case’s demonstration of challenges to prosecution evidence in a drunk driving case. In the case, the defendant was pulled over and given a field sobriety test, during which he seemed largely fine. When the driver blew into a breath testing device, he tested above the legal limit for alcohol.

His attorney learned that the driver had been on the keto diet, and also learned that some breath testing machines cannot tell the difference between isopropyl alcohol and ethanol alcohol. These facts were relevant because when people are on the keto diet, their livers break down fat to use as fuel, which has acetone as a byproduct. When people who are on the keto diet breathe into some breath tests, the devices pick up on the acetone that is released in the person’s breath as isopropyl alcohol.

Most law enforcement agencies use fuel cell-based devices, which they claim can differentiate between the two kinds of alcohol. Breath tests that are based on semiconductors cannot tell the difference. It is not a strong enough challenge simply to be on the keto diet in most drunk driving cases; law enforcement is likely to have other evidence to support its case as well.

Those who are charged with drunk driving offenses in New Jersey might want to speak with a lawyer. A criminal defense lawyer may be able to find ways to challenge the admissibility or strength of prosecution evidence. He or she may be able to have evidence excluded, for example, if the defendant’s Constitutional rights have been violated. An attorney may also be able to negotiate a plea bargain out of court if there are weaknesses in the prosecutor’s case or other extenuating circumstances.