Magistrates are to consider asking the Government to reverse the controversial reclassification of cannabis.
A motion at the Magistrates' Association's annual conference will claim that moving the drug from Class B to Class C has led to greater use of the drug and given out the wrong messages to young people.
JPs will discuss next month whether to call on Ministers to overturn the downgrading of the drug, which came into force in January 2004.
The motion was put forward by members of the association's youth courts committee including vice-chairman Ted Weston of the Buckinghamshire bench.
Former Home Secretary David Blunkett moved cannabis to Class C - making possession a non-arrestable offence in most cases - to give police more time to concentrate on tackling hard drugs like heroin and crack.
In January this year, former Home Secretary Charles Clarke said he would not toughen cannabis penalties despite fresh fears about its side-effects. Experts are working on plans for a complete overhaul of the way drugs are categorised and prohibited.
The Police Federation, which represents 138,000 frontline officers, has said the reclassification was a mistake, but the policy has been consistently backed by chief constables' group, the Association of Chief Police Officers.