What trips people up most is that alcohol can sometimes be created inside the body without anyone taking a drink. That is endogenous ethanol production: a natural process where small amounts of ethanol are formed during digestion or fermentation, usually by yeast or bacteria in the gut, and sometimes linked to medical conditions such as auto-brewery syndrome, diabetes, or severe digestive problems. In most healthy people, the amount is tiny and not enough to explain obvious intoxication, but in rare cases it can matter.

Practically, this issue comes up when a blood, breath, or urine alcohol result does not match the person's behavior, medical history, or timeline. If someone claims the body made the alcohol, that is not something to argue from the shoulder of I-55 or at the crash scene. It takes medical records, lab work, timing evidence, and often an expert who can connect symptoms, food intake, medications, and test results. Chain of custody and proper testing still matter, because blood alcohol concentration (BAC) numbers can be challenged for more than one reason.

For an injury claim, the stakes are obvious. A DUI allegation can shape liability, insurance negotiations, and witness credibility. Mississippi uses a pure comparative fault rule, so even if alcohol is part of the dispute, fault still has to be sorted out percentage by percentage. Endogenous production is a narrow defense, not a magic one, and it usually needs real proof fast.