Millions of pounds seized from drug dealers should be funnelled into a new independent researcher in a bid to tackle the country's drug problems, campaigners have said.
In a highly critical report, the UK Drug Policy Commission (UKDPC) warned a lack of leadership and high turnover of ministers and civil servants were hindering progress.
A new body funded by up to £10 million a year in cash raised through the confiscated assets of drug-related crime is required to improve drug policy, the UKDPC said, while politicians should establish a cross-party forum to decide where progress could be made.
The 18-month study, titled How to make drug policy better, comes after Prime Minister David Cameron ruled out a fundamental review of the Government's approach to drugs.
Mr Cameron dismissed calls from the cross-party Home Affairs Select Committee to hold a wide-ranging Royal Commission to consider alternative approaches, including legalisation.
Discussing the process for testing the effectiveness of policies, a senior political adviser told the UKDPC: "Our impact assessment system is broken and needs to be completely reformed."
The report, based on interviews with former home secretaries, drugs ministers, senior civil servants and policy experts, warned there is a lack of serious discussion about the aims of drug policy and options are not adequately researched or tested.
The UK also lacks evaluation of existing and alternative policies, according to the research, while a rapid succession of drugs ministers is harming efforts to improve policy. There have been four drugs ministers and three Home Office civil servants with lead responsibility for drugs since the 2010 election, the UKDPC said.
UKDPC chief executive Roger Howard said: "We have not been taking evidence seriously. As a result we are spending billions of pounds a year tackling drug problems, without always knowing what difference it makes.
"We need a body that takes responsibility for collecting and sharing evidence. Until we get serious about this, we will continue to be driving blind with many of our drug policies. At the moment, no-one can say that much of what we are doing in enforcement and prevention offers value for money."