Over the past 20 years or so, Brighton has gained an enviable reputation for being cool. Its thriving centre plays host to a young population and the town is one of the most gay-friendly in Europe.

But Brighton also has a drugs problem: there was an average of almost one drug-related death every week – 50 in total – in 2009, and last year around 35 deaths were attributed to drugs. Brighton is the drug death capital of the UK, with the highest mortality rate from drugs per capita.

The situation is not expected to improve soon. "There was a bad crop in Afghanistan last year, which meant the heroin being taken recently was of very bad quality. A lot of the time it will have been dust", said Mike Pattinson, the director of operations for CRI, a charity rehabilitating drug users in the city. "But we hear this year's crop is a bumper one, which means the quality will be much higher and people will overdose. They won't cope with the strength of what they are taking."

Caroline Lucas, MP for Brighton Pavilion, has called for a new approach, having identified an unlikely ally. She wants to exploit the localism agenda of communities secretary Eric Pickles, the no-nonsense cabinet bruiser from Bradford, to decriminalise drug use in the city.

If Lucas, the first Green MP in England, gets her way, a town which has gained a reputation as one of the most tolerant in the country will become a pioneer in liberal drugs policy as well.

She claims the government's localism strategy echoes, at least on the surface, the Global Commission on Drugs Policy's recent recommendation that local administrations be allowed to develop their own approaches, if there are grounds to believe these will deliver improved health or social outcomes.

If her argument is accepted, Brighton will attempt to amend the laws on drugs and criminality for a trial period.

Her plan, she insists, does not stem from a desire to foster the cannabis cafe culture of Amsterdam on the south coast, but because the death toll demands a rethink. "The current free-for-all in which anyone can manufacture, sell or get hold of drugs needs to end — through proper regulation, strict controls on who can buy what and when, and ending the criminal control of drug markets," Lucas recently said in a speech to health workers.

"I think somewhere like Brighton should be able to say our experience shows that prohibition and abstinence don't work — and we want to try something different."

Strikingly, Lucas has the measured support of the senior police officer in this most cosmopolitan of cities. Chief Inspector Graham Bartlett knows he is on perilous ground, but his 22 years working with drug users has persuaded him that now is the time for change.

"It is important to say first of all that what I am expressing is a personal view and my officers will enforce the law as it stands," Bartlett told the Observer. "But we have drugs usage which is worse than Liverpool and parts of London, and though drug addiction is properly regarded in the country as a physiological addiction we deal with it as a crime. The people who manufacture drugs and supply them should be jailed, but the people that use them need treatment."

Bartlett said people would feel less at risk of criminal records and criminal convictions – and therefore more willing to seek treatment.

Ten years ago Portugal abolished criminal penalties for possession of drugs. Instead those caught with drugs for personal use are sent to so-called "dissuasion boards" consisting of social workers and psychologists who question users on their drug habit and have the power to impose fines or recommend treatment.

Users caught with drugs more than once are ordered to appear at police stations or a doctor's surgery.

The result, according to a study, is that drug use among teens in Portugal has declined, rates of new HIV infections caused by sharing of dirty needles have dropped, while the number of people seeking treatment for drug addiction has more than doubled

Such an approach would not be entirely alien to the south coast of England. While the death rate may be high in Brighton, Pattinson and his team at the CRI are proud of what they have achieved recently in preventing worse.

The charity runs a needle exchange and drop-in centre a short stroll from the front by Victoria Gardens, one of the city's most popular parks. There is no sign on the navy blue shop front and the lightly frosted glass prevents those passing by from peering in. But inside it is bright and airy. And what they do here is to treat those coming for help – be it a clean needle, advice or therapy – as clients, not as criminals.

"We want to be a friendly face," said the centre's manager. "We probably get 30 people coming through our door every day and we try to help. If it is a matter of swapping needles, then we are at least in contact and we can build relationships and offer advice."

There are more than 700 registered needle exchange users and the service distributed 195,000 needles last year with a 99% return rate.

But crucially there were also 1,140 people in treatment – of whom 383 were new, while 144 of them left the service drug free.

Meanwhile, CRI works with Bartlett on Operation Reduction which has seen the charity focus on "user dealers" on the streets, while the police seek to cut off supply. It has had impressive results.

Pattinson said: "It is no good arresting street level dealers and putting them in prison for three or four weeks because it is such a lucrative market; there are so many vulnerable people you just get more taking their place.

"Caroline Lucas is pushing at an open door here. She wants evidence-based policy, and we simply say it would be madness to have anything other than policy based on evidence."