“Auto-Brewery” Syndrome as a Nevada DUI Defense
Explained by Las Vegas Drunk Driving Defense Lawyers

man blowing into handheld DUI breath testing device

Can auto-brewery syndrome "trick" a Nevada DUI breath test?

“Auto-brewery” syndrome -- also known as gut fermentation syndrome -- is a rare medical condition in which a person's digestive system produces its own ethanol. The technical term for this is “endogenous fermentation.”

Ethanol – also referred to as ethyl alcohol – is the type of alcohol found in alcoholic beverages.

Is auto-brewery syndrome real?

Claimed instances of auto-brewery syndrome are extremely rare and, therefore, controversial.

According to a 2000 article on auto-brewery syndrome as a drunk driving defense in the British journal Medicine, Science and the Law, concentrations of blood alcohol in people whose systems self-produced alcohol “are far too low to have any forensic or medical significance.”[1]

However, some doctors claim that auto-brewery system is real. They say that carbohydrates have the potential to be fermented in the upper gut. This can result, these doctors say, in medical problems that can include irritable bowel or bladder, arthritis, fibromyalgia and chronic fatigue syndrome.[2]

Can self-produced alcohol “fool” a Nevada DUI breathalyzer?

Nevada DUI breath tests work by measuring the amount of alcohol in your breath. The breath testing device than mathematically converts this quantity to an equivalent blood alcohol concentration or “BAC.”

The problem is that Nevada breath testing devices are supposed to measure “deep lung” air. This is because some of the alcohol absorbed by the bloodstream when we drink alcoholic beverages passes from our capillaries (tiny blood vessels) into the lungs.

When we exhale this deep lung air, it can be captured by a Nevada breath testing device. The device can then measure the alcohol in our breath and come up with a reasonable (though not strictly accurate) approximation of the amount of alcohol in our blood.

However, before deep lung air can pass into a breath testing device, it must pass through our throat and our mouth. If there is any alcohol there, the device will assume it came from deep within our lungs.

Imagine, for instance, that you swish some alcohol in your mouth and spit it out. If you were to then take a Nevada DUI breath test, the device would register you as drunk – even though the alcohol never passed into your bloodstream.

Breath testing device manufacturers claim their equipment can tell the difference between the alcohol in deep lung air and mouth alcohol.[3] But tests have shown this isn't always the case.

Wouldn't alcohol in the digestive tract make you drunk?

When we drink, most alcohol is absorbed in our digestive tract. But some is excreted in our urine and in our breath (which is how a breath-testing device can measure it).[4] If we drink too much, however, our kidneys and lungs can't keep up. The excess alcohol passes into our bloodstream.

So the short answer is yes -- too much alcohol in the digestive tract, regardless of the source, will eventually make you drunk.

However, for reasons that are poorly understood, it appears that it may take more than .08% of self-produced alcohol to make people with auto-brewery syndrome drunk. On her arrest, one woman with auto-brewery syndrome blew a .40% -- five times the legal limit in Nevada for an adult.

According to her lawyer, however, the woman exhibited no signs of intoxication until she reached a blood alcohol level of between 0.30% and 0.40%. A judge apparently agreed, and her New York DUI case was dismissed.

There are other reports, however, of people with auto-brewery syndrome becoming drunk after eating carbohydrates. If you know you are ones of these people, a DUI defense based on auto-brewery syndrome is unlikely to be successful.

Is auto-brewery syndrome a legal defense to DUI in Nevada?

Auto-brewery syndrome has yet to be tested as a DUI defense in Nevada. However, defenses based on other digestive disorders – such as gastroesophageal reflux disease (GERD) – can sometimes be successful.

Until it is actually tested in court, there is no way to know whether a defense based on auto-brewery syndrome would work. It would most likely prove a success if you didn't know you had it or it had never made you "drunk." Otherwise, it could be argued, eating your trigger foods would make you just as guilty as if you had drunk too much alcohol.

But there other ways to beat a Nevada DUI…

Arrested for DUI in Nevada? Call us for help…

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If you or someone you know has been charged with a Nevada DUI, we invite you to contact us for a free consultation.

Our caring Las Vegas and Reno, Nevada DUI defense lawyers know that there are many ways to challenge your Nevada DUI charges – from asserting a medical condition to challenging the legality of your arrest.

Call us at 702-DEFENSE (702-333-3673) or fill out the form on this page to schedule your free consultation.

And to learn about DUI defenses based on medical conditions in California, please see our article: How conditions such as GERD can “trick” a California DUI breath test.

Legal references: 

  1. Logan BK and Jones AW, Endogenous ethanol 'auto-brewery syndrome' as a drunk-driving defence challengeMed Sci Law. 2000 Jul;40(3):206-15.
  2. See, e.g., Dr Sarah Myhill and Craig Robinson, Fermentation in the gut and CFS.
  3. See, e.g., Jeanne Swartz, Breath Testing for Prosecutors: Targeting Hardcore Impaired Drivers, American Prosecutors Research Institute.
  4. MedicineNet.com, How is Alcohol Metabolized?; Brown University Health Education, Alcohol and Your Body.

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