A new body is needed to assess existing and alternative drugs policies, and could be partly funded by assets seized from dealers, campaigners have said.
The UK Drug Policy Commission said billions of pounds a year were spent tackling drug problems, "without always knowing what difference it makes".
The new body would collect and share evidence so policy-makers were not "driving blind", the UKDPC said.
It called for politicians to establish a cross-party forum on the issue.
In October, the UKDPC published the results of a six-year study of drug policy suggesting that of £3bn a year spent tackling drug problems in the UK, at least £2bn was not supported by clear evidence.
In its latest study, titled How to Make Drug Policy Better, the body said there was a lack of serious discussion about policy, as well as a lack of research and testing of different strategies.
"We have not been taking evidence seriously," said chief executive Roger Howard.
"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."
The report is based on interviews with former home secretaries, drugs ministers, senior civil servants and policy experts.
It complained about a lack of leadership on the issue, adding that a high turnover of ministers and civil servants was also hindering progress.
Since the 2010 election, it said, there had been four drugs ministers and three Home Office civil servants with lead responsibility for drugs.
The report suggested a new independent body could provide leadership, assess drug and alcohol strategies and commission new research.
As well as receiving funding from various research councils, there could be a strong case for channelling assets seized from drug-related crime, the UKDPC suggested.
Earlier this month, the cross-party Commons Home Affairs Committee urged the government to establish a royal commission to consider alternative policies - including possible decriminalisation.
But Prime Minister David Cameron quickly ruled out the suggestion, saying: "I don't support decriminalisation. We have a policy which actually is working in Britain."