The move is the first tacit acceptance by the Government that the application of the cannabis law in Britain needs examining and comes at the end of the third week of the Independent on Sunday's campaign for the decriminalisation of cannabis for medicinal and personal use.
Last week, the IoS asked each member of the Cabinet if they had ever personally used cannabis. Of the 22-strong Cabinet, 17 refused to reply and four - Tony Blair, John Prescott, Ron Davies and Lord Richard - sent under separate cover the same answer: "We do not take part in surveys. Jack Straw has made the Government's position perfectly clear. We shall not decriminalise, legalise or legitimise the use of drugs." Harriet Harman's office said: "The minister does not wish to reply."
Rosie Boycott, IoS editor, said she was disappointed with the response because ministers had failed completely to answer the simple question. "It was not a survey but a question for each Cabinet member," she said.
However, for the first time a senior Labour figure has broken ranks to support the campaign. Ken Livingstone, the left-wing MP who hopes to become the first Mayor of London, has put his name to the list of supporters for decriminalisation. His signature brings the number of aspiring mayors in favour of decriminalisation to three: Richard Branson and Simon Jenkins are also on the list.
Also throwing their weight behind the campaign today are John le Carre, Janet Suzman, Peter Gabriel, Dave Stewart and Michael Frayn.
In a phone-in poll conducted early last week, readers of the IoS voted overwhelmingly in favour of relaxing the law. Of the 5,830 callers, 5,402, or 93 per cent, voted "yes" and 428, or seven per cent, said "no".
Mr Straw is concerned that the 43 police forces in England and Wales have too much discretion over the way in which they deal with cannabis possession cases, resulting in an inconsistent response. For an identical offence, it is up to the police in each area whether they prosecute, issue a caution or take no action at all.
One Whitehall source said that Mr Straw, "has the view that there has to be a more co-ordinated approach but that possession isn't treated as a throwaway crime". A likely outcome is a set of recommendations for chief police officers to bring them into line.
One other possibility, the introduction of a series of a scale of fixed penalties for soft drugs cases - similar to motoring offences - was discounted by government sources last week on the grounds that it would require a change in the law. Fixed penalties would not result in a criminal record and would effectively be a major step in the decriminalisation of cannabis.
A similar scheme was proposed for Scotland in 1994 by the then Scottish Secretary, Michael Forsyth, but was blocked by the then Home Secretary, Michael Howard. He instead amended the Criminal Justice Bill to increase the maximum fine for possession of marijuana from pounds 500 to pounds 2,500.
A review of the way the drugs laws are enforced is likely to be welcomed by many police officers. At the Labour Party conference this month, Fred Broughton, chairman of the Police Federation, said: "In our view, it is crucial that when it comes to drugs, chief officers should be singing from the same hymn sheet."
Campaign latest, pages 22-24