Analysis By Nick Assinder Political correspondent, BBC News website

The fact that Home Secretary Jacqui Smith broke the law by smoking cannabis 25 years ago will overshadow her announcements on the government's crime strategy.

Ms Smith says she was wrong to smoke cannabis

But does the fact that a politician, or anybody else, once took cannabis really matter any more?

Will voters rise up in horror and demand Ms Smith's sacking, as may well have been the case a decade or so ago, or will they shrug their shoulders and declare "so what".

Is it even a question that is any longer worth asking politicians who, as David Cameron always insists when refusing to answer, say they deserve to have a private life before they entered politics.

And why does the government believe the time is now right to consider overturning Tony Blair's decision of three years ago to downgrade the drug from Class B to Class C?

No effect

It certainly seems to be the case that public opinion on the use of cannabis has changed dramatically over the past couple of decades.

So much so that, in 2000, eight members of the then shadow cabinet felt able to make public admissions that they had tried it at some point in the past in order to stop attempts by Ann Widdecombe to toughen laws on possession of the drug.

Cannabis was downgraded three years ago

And there has been a long line of senior politicians who have now also made similar confessions without any negative impact on their careers or public standing.

Having said that, they are often keen to stress that they did not enjoy the experience, or found it had no effect on them.

They include those senior Tories, amongst them Francis Maude, David Willetts and Oliver Letwin and former home secretary Charles Clarke and current drugs minister Vernon Coaker.

Undoubtedly one of the reasons politicians go public is that there is always the likelihood their past behaviour will be uncovered and "revealed", so it is better to come clean and win a few honesty points into the bargain.

That is particularly true as there seems to be little or no downside to such a confession any more.

There may even be a bonus in being seen as a "normal" human being with experiences similar to many other individuals. As Mr Cameron puts it, having had "a normal university experience".

More powerful

It is also the case that, over the years, cannabis has come to be seen as a relatively harmless drug, more on a par with tobacco and alcohol than harder drugs like heroin and cocaine.

Mr Cameron says politicians deserve a private past

It was that view that partly led to the downgrading of cannabis three years ago.

But attitudes on such matters are constantly evolving and the relatively benign view of cannabis is now being widely challenged, including by the current government.

It is being pointed out that new, hybrid forms of the drug, known as skunk, are many times more powerful than more "traditional" forms and are said to be responsible for behavioural and psychological problems amongst some users.

It is that growing body of evidence which has sparked serious concerns amongst many doctors and social workers, and led to demands for a government re-think on the classification of the drug.

Hence the review, announced by Gordon Brown on Wednesday and to be launched by Ms Smith next week, on how strict the laws covering cannabis should be.

The challenge of putting out a consistent message on cannabis in that review will provide a considerable challenge.

On the one hand there are ministers admitting to past cannabis use and expecting no serious consequences, on the other they are attempting to warn that the drug may not be as benign as thought and that punishments should be toughened up.

And it is exactly that tightrope which the current home secretary is trying to walk.