Luciana - An unlucky event

An unlucky event happened to a friend of mine last year.
It looked like all one evening and he was going to take his girlfriend with his car when police stopped him at a checkpoint and forced him to do the alcohol test. To his surprise, the test is positive and even with a high number. The police decided to confiscate his driving license as punishment.
My friend was absolutely sure he had not drunk anything and can not believe how the test will be positive, but remembers that he used the mouthwash just before going out.He Suggested the hypothesis to the police and then they decide to take him to the hospital for blood tests. Sure enough, the analyzes were negative. Doctors confirmed the theory of the boy: Some mouthwashes have a high level of alcohol and may affect the results of the alcohol test.
His only sentence at the end of this story was, "If I had not thought about the mouthwash, at this time I would not have a driver's license."