Man was six times over limit.
Patrick Lowther, 33, a member of the gipsy community, died in January 2003, two months after he was arrested by North Yorkshire Police on suspicion of drink-driving.
A jury at Teesside Coroner's Court was told that Mr Lowther became unconscious after being put in the back of a police van.
He was taken to York District Hospital, and was later transferred to the University Hospital of North Tees at Stockton, where he died.
The jury heard Mr Lowther, of Cornfield Road, Fairfield, was arrested after driving a Vauxhall Astra van to the Selby area of North Yorkshire on November 12, 2002.
He was found to have an alcohol level of 513mg in 100ml of blood. The legal limit is 80mg, making him more than six times over the legal limit.
A post mortem examination showed the cause of death to be broncho-pneumonia due to brain damage.
The inquest heard that at the time of his death Mr Lowther was being fed through a tube because of the severity of his brain damage.
Home Office pathologist Dr Nigel Cooper said there was no evidence of natural disease, adding that it seemed likely that Mr Lowther collapsed because of alcohol intoxication.
Barrister Caroline Goodwin, representing Mr Lowther's family, said there was no dispute that Mr Lowther drank excessively.
But she said prior to getting in the police van he was capable of providing a breath test.
Pathologist Dr Cooper said: "I was told he walked to the police van. He certainly wasn't unconscious at that stage."
He was suffering from chronic pancreatitis and just weeks prior to his death he had been an in-patient at the University Hospital of North Tees.