Abortion. Drugs. Gays. Transsexuals. We're not a progressive nation, are we?

Here's one that David Blunkett does not need to agonise over. Yesterday the European Court of Human Rights, in Strasbourg, upheld Christine Goodwin's right to be a woman. The judges unanimously ruled that her country – Britain – had breached her right to privacy and her right to marry by refusing to accept that, though born a man, she was now a woman. Incidentally, the other three countries who are in the same boat as us are Ireland, Andorra and Albania.

You can just imagine, however, what would have happened had there been no Strasbourg court and had the Home Secretary proposed action himself. Various newspapers would have declared that this was "political correctness gone mad", phone-ins would have asked how such legislation could be a priority at a time when policemen are crumbling and there aren't enough hospitals on the street. Then the legislation would have been held up for a thousand years in the Lords while Baroness Young argued that it was bound to lead to thousands of impressionable young men getting carried away and becoming young women.

This is not a country to be bold in, as evidenced by the reaction to David Blunkett's decision, announced on Wednesday, to reclassify cannabis from a Class B (Bad) drug to a Class C (be Careful) one. Immediately Brixton was scoured for bobbies who thought it was a disaster, newspapers that – six months ago – thought reclassification was a neat idea suddenly got a fit of the vapours when confronted with real action, and the drugs tsar upped and resigned.

Changing the drugs laws is complex enough. Changing them in Britain is a labour of Hercules. Look at what Mr Blunkett feels forced to say. The journalists ask him, of cannabis: "Is it bad for you, and is it wrong?" To which Labour's own Hercules answers: "Yes and yes." But what he really means is: "A little bit and no, it isn't." How can it be "wrong" per se to smoke or eat cannabis? The missing question, though, was: "Is it pleasant?"

In the House, the admirable Conservative home affairs spokesman Oliver Letwin understands the logical flaw in Blunkett's public reasoning. Well, who doesn't? If you let people consume a product, but make the selling of the product illegal, you hand supply over to criminals. QED. Letwin's answer to this conundrum, however, is obscure. Does he choose vigorously to prosecute cannabis consumers, or does he take the opposite logical course and legalise the sale of spliffs? Um, no.

We have only got to this point because: (a) the police have, effectively, demanded it; and (b) cannabis-taking is pretty universal among the young in this country. It is, partly, the change in public opinion that emboldens a Home Secretary who is more than usually sensitive to shifts in the popular mood.

His incremental pace, however, is dictated by a determination not to do the right thing before enough people realise that it is the right thing.

Look back at the history of social reform in this country, and you can see that Blunkett's carefulness is typical. In 1861 the Offences Against the Person Act made it illegal "to procure a miscarriage" (ie carry out an abortion). The penalty was life imprisonment. It took another 75 years before the Abortion Law Reform Association (ALRA) was formed. In 1938, Dr Aleck Bourne, a gynaecologist, invited the police to prosecute him for performing an abortion on a 14-year-old rape victim. Bourne was acquitted on the grounds that he had acted to prevent the girl from becoming a "physical and mental wreck".

A year later, a government committee recommended changes to the abortion laws, but nothing was done. It wasn't until the thalidomide tragedy in the early 1960s that abortion became a matter of wide public controversy. When – at last – in 1967 a Bill liberalising the law passed though the Commons, it was a young Liberal MP who sponsored it – not the Health Secretary. It was a rough ride. And even then the new law did not apply to parts of the UK.

Gay law reform has taken even longer. After a series of scandals, largely caused by police overzealousness, the Wolfenden Committee was set up in 1954 to consider the laws on homosexuality. In 1957 the committee recommended liberalisation, and the first parliamentary debate on the subject was held in December that year. The then Home Secretary parked the Wolfenden recommendations, arguing that they wouldn't enjoy the support of the general public. More research, he said, was needed. That's the way it stayed for another 10 years, until the Sexual Offences Act was passed. Even this put the age of gay consent at 21 and made homosexuality a criminal offence if more than two people were present.

Some Labour ministers feared the public reaction. Richard Crossman, in his diary for 3 July 1967, wrote of the Bill: "It may well be 20 years ahead of public opinion; certainly working-class people in the north jeer at their Members at the weekend and ask them why they're looking after the buggers at Westminster instead of the unemployed at home."

Just last year, the Lords were refusing to accept an equalisation of the gay age of consent, and the right of gays to serve in the armed forces was only upheld by a judgment from the European Court of Human Rights. In all cases it was argued that liberalisation of the law was running ahead of public opinion.

The abolition of capital punishment was even more tortuous. In 1908 it was abolished for people under 16; in 1922 for maternal infanticide; in 1931 for pregnant women; in 1933 for the under-18s. In 1957, following the wrongful hanging of Timothy Evans, the ultimate penalty was restricted to murder in the course or furtherance of theft, murder by shooting or causing an explosion, murder while resisting arrest or during an escape, murder of a police officer or prison officer and for two murders committed on different occasions. So if you strangled two people at the same time, you were OK, as long as you weren't robbing them and they weren't police officers. Not until 1969 was the death penalty abolished for murder altogether.

In each case, necessary action awaited the creation not of a majority for change, but of a critical mass of law-makers, enforcers, professionals and a progressive section of society. And in each case the progression was uneven and met by hostility.

So, one day (round about the same time as Andorra) we will legalise marijuana and drugs such as ecstasy, regulate their quality by law and then launch education campaigns to persuade youngsters not to use them in school hours, drivers not to take them, and spliff-smokers to find a less harmful way of ingesting their jollies. Gradually, over time, we will cease the demonisation of pushers – not because they are a fine upstanding group of men and women, but because drugs are about demand pull not supply push. The problem with drugs is pullers, not pushers, and they need education, not punishment.

d.aaronovitch@independent.co.uk