The lowering of the legal classification of cannabis has been cautiously welcomed in Truro, but many feel that the law needs clarifying.

From tomorrow, cannabis will be down-graded from class B, where it has been placed with amphetamines and barbiturates for the past 30 years, to class C along with those drugs considered less harmful, such as anabolic steroids.

Alongside the new classification the government has issued guidelines to help police forces interpret the new laws, in which the key change will be a "presumption against arrest" when offenders are caught with small amounts.

According to inspector Mark Richards, of Truro police, an offender is arrested in nine out of ten cases when police discover the drug. Under the new guidelines he expects the number of arrests to go down, but not necessarily seizures of the drug. "Anything that frees up more resources for fighting harder drugs is a welcome measure," he said.

However, police in Truro were quick to point out that the new measures do not mean that users and dealers of cannabis are immune from the law, saying it only means that police have "more discretion" over arrest.

PC Bob Wheeler at Truro police said: "Some people might think that these new laws mean that you can't be arrested if you are caught in possession of cannabis. You can!

"What the new guidelines mean for us is that we have more discretion over how we deal with offenders. We will still arrest people who are smoking it in public view, especially near places where young people are present.

"We will also arrest when the offender is under 18 or a vulnerable person, and also if they are a repeat offender. But even if you don't fall into one of these categories, the police still have the power to arrest you," he said.

Last week the Packet hit the streets of Truro and found that people from all walks of life support the changes, but a degree of confusion still remains.

Manager of the Cornwall Sports shop and mother of two teenage boys, Judith Whitehouse, said she welcomed the changes. "I think it is very sensible, but I think it is time they legalised all drugs," she said. "In all countries that they have legalised it drug use and drug related crime has gone down. I don't think it leads on to harder drugs anymore than booze," she said.

A Big Issue seller in the city, who preferred to be known only as Ben, said he had been living on the streets for a year, and has seen a side of Truro invisible to many of its residents. "Sadly enough it is easier to score heroin here than it is cannabis," he said. Personally I think its time they legalised the lot."

Ben said that he knew of people who were addicted to heroin that regularly went out and stole to supply their habit. "I don't think cannabis is that harmful a drug. When you compare cannabis to alcohol in terms of deaths it fades in comparison and it doesn't ruin people like heroin does," he said. Some residents were less applauding of the new legislation. Young couple Erica Mayle and Rick Taylor took a more cautious approach.

"They need to make the whole thing a lot clearer. People are going to start smoking it anywhere thinking they can," said Ms Mayle.

Mr Taylor said: "I think that it's not going to be a bad thing, but to be honest I don't think it will make much difference to people who smoke it."

Imogen Holt, chief executive of the Freshfields Service in Truro, which provides drug advice, said: "The very strong message to make is that it is still illegal."