A six-year study of Britain's drug laws by leading scientists, police officers, academics and experts has concluded it is time to introduce decriminalisation.
The report by the UK Drug Policy Commission, an independent advisory body, says possession of small amounts of controlled drugs should no longer be a criminal offence and insists the move will not lead to a significant increase in use.
The experts say the criminal sanctions faced by the 42,000 people sentenced each year for possession of all drugs - and the 160,000 given cannabis warnings - should instead face simple civil penalties such as a fine, attendance at a drug awareness session or a referral to a drug treatment programme.
They also say that imposing minimal or no sanctions on those growing cannabis for personal use could go some way to undermining the burgeoning illicit cannabis factories controlled by organised crime.
But their report rejects any more radical move to legalisation, saying that allowing the legal sale of drugs such as heroin or cocaine could cause more damage than the existing drugs trade.
The commission is chaired by Dame Ruth Runciman with a membership that includes the former head of the British Medical Research Council, Prof Colin Blakemore, and the former chief inspector of constabulary, David Blakey.
The report says their analysis of the evidence shows existing drugs policies struggle to make an impact and, in some cases, may make the problem worse.
The work of the commission is the first major independent report on drugs policy since the influential Police Foundation report 12 years ago called for an end to the jailing of those possessing cannabis.
The report says that although levels of illicit drug use in Britain have declined in recent years, they are still much higher than in many other countries.
The UK has 2,000 drug-related deaths each year and more than 380,000 problem drug users.
The 173-page report concludes: "Taking drugs does not always cause problems, but this is rarely acknowledged by policymakers.
"In fact most users do not experience significant problems, and there is some evidence that drug use can have benefits in some circumstances."
The commission's radical critique says the current UK approach is simplistic in seeing all drug use as problematic, fails to recognise that entrenched drug problems are linked to inequality and social exclusion, and that separating drugs from alcohol and tobacco use makes it more difficult to tackle the full range of an individual's substance use.
It says the £3 billion (HK$37 billion) a year spent tackling illegal drugs is not based on any evidence of what works, with much of the money wasted on policies that are not cost-effective.
It argues that even large-scale seizures by the police often have little or no sustained impact on the supply of drugs.
It also argues that "Just Say No" campaigns in schools sometimes actually lead to more young people using drugs and that pushing some users to become abstinent too quickly can lead to a greater chance of relapse or overdose and death.
Blakey, also a former president of the Association of Chief Police Officers, said the current approach of police taking action against people using drugs was expensive and did not appear to bring much benefit.
"When other countries have reduced sanctions for low-level drug users, they have found it possible to keep a lid on drug use while helping people with drug problems to get into treatment," the former chief constable said.