A senior Met Police officer who drew up the force's anti-drug strategy could be sacked for refusing to provide a urine sample for cannabis testing.
The actions of Cdr Julian Bennett, who joined the Met in 1976, were found to have amounted to gross misconduct.
He was cleared by a three-person disciplinary panel of smoking the illicit substance.
His former flatmate Sheila Gomes accused him of using it daily before heading to work at New Scotland Yard.
She reported Mr Bennett in July 2020 and, in the presence of an assistant commissioner, he was asked to provide a sample.
He offered to resign on the spot instead, and asked for a meeting with then-commissioner Dame Cressida Dick.
Mark Ley-Morgan KC, representing the Metropolitan Police, said it would have smacked of "organised corruption at the highest level" if he had been allowed to resign on the spot.
Mr Bennett, who wrote the force's drugs strategy for 2017-21, said he had been taking CBD (cannabidiol) to treat facial palsy and was worried the sample would come up positive for an innocent reason.
During the tribunal in Southwark, south London, his lawyer John Beggs KC branded Ms Gomes a "liar" and a "fantasist" who he said wanted to write a book about the claims and make money.
By failing to provide the sample, Mr Bennett, who has been suspended on full pay since July 2021, was found to have breached force standards for honesty and integrity, orders and instructions and discreditable conduct.
Panel chairman Akbar Khan said: "It is highly improbable the officer believed he had a good reason for failing to comply with a lawful order.
"Harm has undoubtedly been caused to the reputation of the Metropolitan Police Service."
He said Mr Bennett's behaviour was "deliberate and intentional, seeking a personal advantage or special treatment from the commissioner" and that he would have had a "unique insight" into what would have been a good reason.
Freedom of information requests showed Mr Bennett presided over 74 police misconduct hearings involving 90 officers between June 2010 and February 2012.
Of the hearings involving Mr Bennett, more than three-quarters of officers were dismissed.
A decision on whether he should lose his job will be delivered later.
Mr Beggs KC has indicated that the gross misconduct finding would be appealed.