Now for a short break from free speech

We are careless about freedom of speech in this country. In the United States, they wrote it into their constitution. Amendment number one: "Congress shall make no law ... abridging the freedom of speech."

In Britain, we have a lazy assumption: that you can say what you like as long as it is not defamatory, or obscene, or an incitement to violence or racial hatred.

Well, you can in the limited sense that you can stand on a soapbox in Hyde Park or Brixton. But the First Amendment takes into account that, in order to disseminate information and opinion widely, you need something more expensive than a soap box. Hence the next clause, "... or of the press". And that has been interpreted by the American courts to mean freedom of access to all means of mass communication.

So, in the US, if enough people feel strongly enough about cancelling Third-World debt, they can club together to make a television commercial which tries to persuade their fellow citizens, and the American government, of the justice of their case.

In Britain, they cannot. Christian Aid has made a commercial which dramatises the effect of accumulated debt in poor countries. "The men we work for lend money to make money. You borrow, you pay it back," say the debt collectors (one white, one black), as they take medicines, food and blankets from a Third-World baby.

The advert has been banned. "No advertisement may show partiality as respects matters of political or industrial controversy or relating to current public policy," says the TV Code of Advertising Standards and Practice.

Public controversy? What about adverts for Working-Out Barbie, the figure that launched a thousand columns of newsprint?

Not that cancelling Third-World debt is that controversial. Most governments and international institutions agree reform is needed and talks are under way. Even Gordon Brown agrees with it. Although that might make it "party- political".

But then on those grounds, if a television commercial suggested that a brand of apple pie reminds you of the ones mother used to make, it would have to be banned. That kind of misty feelgood factor is, after all, one of the official objects of New Labour.

The rules governing what may be shown on television in between biased, controversial, political and generally offensive programmes are ridiculous. They date from the era, which ended in 1956, when all discussion of an issue that was due to come up in Parliament in the next 14 days was banned on television and radio.

They share the assumption which runs through charity law that "politics" is controversial and dangerous, whereas caring for the poor is not. Which ended up in the anomaly of campaigning work by Oxfam and War on Want being ruled "uncharitable" while private schools and political think-tanks of all stripes were granted tax-exempt status.

It is the definition of "political" that is wrong with the present rules for television advertising. It would not, clearly, be right to allow the Trades Union Congress to advertise on television in support of the Liberal Democrats, nor should big businesses be allowed to pay for racing cars to carry "Tony Blair" logos. But in no way can the Christian Aid advertisement be read as a call to "Vote Labour".

Or take the hunting issue. That was the subject of a free vote in the House of Commons. Why should the two sides not be allowed to make their case - within the guidelines on taste and decency - on television, directly, without interviewers or producers shaping what they say and "ensuring balance"?

Despite the parties bemoaning the rise of single-issue pressure groups at the expense of conventional politics, they are precisely the groups who are not allowed to contribute directly to public debate on television. No doubt Greenpeace would still want to take direct action, get in the way of whaling ships and so on, because it is more fun than making commercials. But they should at least be allowed to do so.

Interestingly, Amnesty International last month won a High Court case against the Radio Authority to allow it to advertise - on the grounds that its activities are "humanitarian" rather than political.

But the rules are different for different media, and enforced by different quangos. Politics is allowed on billboards and in print, but subject to other rules, such as taste and decency, which are sometimes enforced erratically - and always after the event - by the Advertising Standards Authority. It ruled that the Conservative "demon eyes" advert attacking Tony Blair should not have been used because it portrayed him as "sinister and dishonest", whereas Labour's "two-faced" John Major escaped censure.

This patchwork quilt of self-regulation means that freedom of speech is a haphazard thing, preserved by custom and practice and despite occasional perverse rulings, so that nobody has a clear idea of what it means.

If we were serious about it, we would define the principle and then recognise the special case for regulating the activities of political parties. We should want the widest and most open public debate that is compatible with a political system driven by democracy rather than money. That means parties should be banned from buying television and radio airtime. Comparing America's cash-driven politics with our system of allocating free airtime according to a democratic formula, it is clear that the British system wins.

So we should make the right to free speech legally enforceable, subject to special rules for political campaigning.

Yes, we would have to stop the equivalent of American political action committees springing up to evade restrictions on spending. And yes, we would have to accept that many of the rich and powerful would use television advertising to try to defend their interests. But if Christian Aid were allowed to put their argument for cancelling Third-World debt on television, unedited and uneditorialised, it would enrich rather than impoverish our democracy.