A Texas attorney who got a man's DUI charge dropped even though a breath test showed him well above the legal alcohol limit says it happened because of the man's low-carb diet. According to the attorney, ketosis resulting from the low-carb diet caused the false positive.
Acetone is a byproduct that occurs during ketosis when the liver is processing fat. People may then breathe out acetone as isopropyl alcohol. Some types of breath tests may not be able to distinguish between this and ethanol alcohol. For example, inexpensive self-check models may be inaccurate for people in ketosis. Air that has alcohol in it does not have the same number of molecules as breath from the lungs, and the device estimates blood alcohol content by analyzing these molecules. However, it might treat isopropyl and ethanol alcohol the same way.
Most law enforcement officers have devices that use fuel cells. Manufacturers say their devices can distinguish between the two types of alcohol, but according to the attorney who defended the man in Houston, there has not been peer-reviewed research that examines this. Furthermore, it is uncertain what would happen if someone in ketosis drank a small amount of alcohol. Machines in police stations that use infrared spectroscopy can distinguish between the two types of alcohol, however. A person may also be able to request a blood test.
People who are facing DWI charges may want to talk to an attorney about their options. For example, if it is a first-time charge, the person might want to try to get the charges dropped. A person who already has multiple convictions may be primarily concerned about avoiding or reducing jail time. A DWI conviction can also affect a person's career. An attorney might consider unusual circumstances, such as ketosis, or look at whether law enforcement violated the person's rights.