The penalties for drug misuse should be relaxed so that possession of small amounts would no longer be a criminal offence, the government has been urged.
The recommendation comes in a report from the UK Drug Policy Commission, which undertook six years of research.
Its detailed report concludes the UK is wasting much of the £3bn it spends each year on tackling illicit drugs.
The Home Office says drug use is falling and it does not plan to alter its approach.
The report, called A Fresh Approach to Drugs, says the annual estimated cost to England and Wales of class A drug use is £15bn.
It says that while drug use and drug problems have declined in the UK in recent years, there are still about 2,000 drug-related deaths each year and 380,000 problem drug users.
