Is it possible to cheat a breath test or fool a breathalyser?

An episode of the popular science show MythBusters tested a number of methods that supposedly allow a person to fool a breathalyzer test. The methods tested included the use of breath mints, onions, denture cream, mouthwash, pennies and batteries; all of these methods proved ineffective. The show noted that using items such as breath mints, onions, denture cream and mouthwash to cover the smell of alcohol may fool a person but since they don’t actually reduce a person’s BAC (Blood Alcohol Content), there is no effect on a breathalyzer test regardless of the quantity used.

Pennies supposedly produce a chemical reaction, while batteries supposedly create an electrical charge, yet neither of these methods affected the breathalyzer results.

The Mythbusters episode also pointed out another complication – it would be necessary to insert the item into one’s mouth (eat an onion, rinse with mouthwash, conceal a battery) to take the breath test and then remove the item – all of which would have to be accomplished discreetly enough to avoid alerting the police officer administering the test. It would likely be very difficult, especially for someone in an intoxicated state, to be able to accomplish such a feat! In addition, the show noted that breathalyser tests are often verified with blood tests, so even if a person somehow managed to fool a breath test, a blood test would certainly confirm a person’s guilt. However, it is not clear why a negative breath test would be verified by a subsequent blood test.