A postman who claimed he was a human pelican who stored alcohol in a pouch in his gullet has been banned from driving for 18 months.
The court heard a tennis ball-size sac was removed from his throat
William Harvey had said he failed a roadside breath test because of his unique medical condition.
However, a sheriff rejected the claim his alcohol reading had been affected by the "balloon" in his throat.
An expert witness told the court he had never seen a case like Harvey's in 40 years as a forensic toxicologist.
Perth Sheriff Court was told that the postman was seen speeding off in the opposite direction after being passed by a police car in September last year.
He admitted that he then crashed the car into a ditch about 400 yards down the Strathtay to Weem road and was climbing out of the window when police arrived.
He said he had only had half a bottle of wine, but had an extremely rare medical complaint which meant he coughed fluid back into his throat.
The former nurse claimed he had choked because of a panic attack and wine he had drunk earlier had returned to the "balloon-like" sac in his neck.
Harvey, 45, from Aberfeldy, admitted in a joint minute that his breath smelled of alcohol when the officers spoke to him.
He admitted giving a positive roadside breath test but disputed having a reading of 99 microgrammes.
He told the court he had been diagnosed subsequently with laryngocele and had an operation to have a sac the size of a tennis ball removed.
"The balloon was being filled up by mucous coming up from my lungs and the contents of my stomach. It's a balloon I can inflate in my own throat.
"We all have it but in most people it lies dormant. Anything I cough or choke up can inflate it.
"If it burst it would drown me straight away. I walked about with a time bomb in my throat."
Sheriff Lindsay Foulis said that regardless of the medical complaint, he had no doubt Harvey was driving while more than double the legal alcohol limit.
He found Harvey guilty of the charge and fined him £600 along with the 18-month ban from the road.