Kentucky residents who have certain medical conditions might blow a false positive on breath tests, but there is some disagreement about how accurate the different types of tests may be. Ketosis, which is a state that a low-carb diet can put people into, may cause people to breathe out isopropyl alcohol, and some breath tests might not distinguish this from ethanol alcohol. Diabetes and GERD are among the other conditions that could lead to a similar false positive.
A Texas attorney was able to get DUI charges against his client who was in ketosis dropped, but manufacturers of breath tests that use fuel cell technology say their devices are accurate. The attorney says that there are not peer-reviewed studies to support this claim. Furthermore, one professor of forensic technology published a paper in 2006 about a man who could not get past the breath test ignition lock on a vehicle while he was in ketosis. This device also used fuel cell technology.
The portable devices that law enforcement carry in their vehicles to do breath tests during traffic stops generally use fuel cells. However, most of them have a device back at the station that uses infrared spectroscopy. According to the Texas attorney, these are capable of distinguishing between the two types of alcohol. People may also request a blood test.
A DUI conviction can have serious consequences that could include fines, jail time, or a suspended license depending on whether or not it is a first-time offense. A DUI can also affect a person's employment. However, people who are facing drunk driving charges may have options other than simply pleading guilty. In addition to questioning test results, an attorney may look at what prompted the traffic stop.