|Confusion over the legal status of cannabis has led to a huge surge in the number of people caught smoking the drug in public.|
In the 12 months between April 2005 and March this year, about 1,100 people were caught with the drug - compared with about 370 in the previous year.
Leicestershire police say the major cause of the threefold rise is down to people's misunderstanding of the law.
The Government reclassified cannabis from a class B to a class C drug in early 2004 in an effort to help police focus more resources on the trade in class A drugs, such as heroin and crack cocaine.
However, police and businesses say that some people seem to believe the classification change means cannabis is now legal.
Sgt Ian Tan, who leads the city centre's Neighbourhood Policing Team, said: "I came across a man strolling down the street smoking cannabis and he told me he thought it had been decriminalised.
"Maybe people are unaware of what the change in the law means but also some of them may just be using that confusion as an excuse."
Under reclassification, the maximum sentence for cannabis possession fell from five years to two, while dealers can face a maximum jail term of 14 years.
Ministers introduced the change so police could concentrate on smashing the class A, hard drugs trade, chiefly in heroin and crack-cocaine.
The guidelines state that people can be arrested if they are publicly smoking cannabis or if they repeatedly offend. They can also be arrested if cannabis use has been linked to other problems in the area, and if you possess cannabis and are close to youth premises.
You will be arrested for cannabis use if you are aged 17 or under.
The cultivation of cannabis is also an illegal offence.
Sgt Mark Parish, deputy commander at Loughborough police station, said: "We are dealing with people on a regular basis who seem to think it's okay for them to smoke cannabis whenever and wherever they want, but clearly that's not the case.
"It's still an illegal drug and some people seem to be unaware of that and are quite shocked when we tell them."
Paul Conneally, of Leicester City Council's substance misuse training team, said schools were spelling out the health and legal implications of drug use.
Mr Conneally said: "The clear message we need to get across is that smoking cannabis is not a safe thing to do and that young people will get themselves a criminal record."
A Leicestershire police spokeswoman said: "Many people believe that the reclassification of cannabis means that it is legal.
"This is not the case.
"Cannabis was re-classified by the Government and Leicestershire Constabulary follows the national guidelines for enforcing the law.
"These figures show that we take drugs misuse extremely seriously and will continue to tackle the issue.
A Home Office spokeswoman said: "It has been recognised that the reclassification of cannabis has led some people to draw the wrong conclusion.
"The bottom line is that cannabis is illegal and will remain so."