An investigation was launched into the conduct of Commander Brian Paddick after his former partner claimed in a newspaper that he smoked cannabis and allowed it to be kept in his home.
The report, from an investigating officer with an outside force, was considered by senior police chiefs on Monday.
Commander Paddick - who denies the allegations - introduced a more lenient police approach to the drug in Lambeth, south London, last year.
Those caught smoking the drug were given a formal warning, rather than arrested, and the cannabis confiscated.
This saved police time and led to reduced reported street crime and burglary in the borough.
But critics claimed it led to an increase in drug tourism in the area and an influx of drug dealers.
Since the newspaper allegations in March, Commander Paddick has been removed from the borough pending the outcome of the investigation.
Commander Paddick, Britain's highest ranking openly gay officer, has also been investigated for alleged breach of police guidelines by not telling his superiors the former boyfriend was on bail for alleged fraud while they were together.
Toby Harris, chairman of Metropolitan Police Authority, has backed the commander's work in reducing crime in one of the country's most deprived boroughs.
As well as a fall in street crime, Lord Harris said burglary had fallen 14% from February 2001 to February 2002.
The Lambeth experiment is being extended nationwide next year when cannabis is downgraded to a Class C drug.
Cannabis users caught three times within a year will face arrest or charges.