Cannabis has now been downgraded

Brixton resident Patrick Strahan said the approach, launched in Lambeth, south London, fuelled crime.

The scheme saw people with small amounts of cannabis given a warning rather than being arrested, saving hundreds of hours of police time.

The Association of Chief Police Officers (Acpo) is also named in the High Court papers.

The policy was brought in by Met Deputy Assistant Commissioner Brian Paddick - who was then Lambeth's police chief.

Cannabis downgraded

The time saved allowed police to focus on street crime and hard drugs.

But opponents argued the experiment led to more drug dealers and users moving into the area and a boom in "drug tourism".

The papers are likely to go before a judge soon who will decide whether there is a case.

The "softly, softly" policy - which ended in Lambeth in 2002 - heralded the downgrading of cannabis from Class B to Class C.

Brian Paddick pioneered the scheme

It was officially downgraded in January this year but police still retain powers of arrest.

Acpo's guidelines say arrests should only be made in aggravated circumstances, such as smoking the drug outside a school.

Police figures show there was a sharp increase in the number of people caught with cannabis in Lambeth following the introduction of the experiment.

And Met Commissioner Sir John Stevens admitted recently that he made a "big mistake" only introducing the scheme in Lambeth, which he said became a "goldfish bowl".

He said it should have been launched in several other London boroughs at the same time.