Joan Bakewell: How come we are so addicted to banning things?

When there's a broad consensus, we use the law. But there is a limit to its effectiveness

Why would anyone want to stop Tom Cruise making a film? He's a global superstar, a ferociously good actor, he's serious about what he does, and he's moving on fearlessly to being a producer. His is an all-round Hollywood success story (if you forgive Eyes Wide Shut and bouncing up and down on Oprah's sofa).

But the German government is delaying his latest project, a film called Valkyrie, which tells of the plot in July 1944 led by Claus von Stauffenberg to assassinate Hitler. The plot came too late, and it failed to kill him. But it is regarded in Germany as one of the heroic events of those terrible years.

Why would a government interfere to stop a specific film? The decision was made by the Ministry of Defence, whose permission is needed for filming on any military site. It refused, and the reason currently being offered is that Cruise is a Scientologist. Apparently the German government does not recognise Scientology as a church, though what that has to do with making films is hard to unravel. Will they ban a tour by Madonna because of her involvement with the Kabbalah Centre? I ask all these questions with a sense of bemusement that governments think its anyone's business but their own which religions people profess.

There are usually two reasons - fame and money. Cruise and Madonna are seen as recruiting sergeants for their particular sects, and their abundant generosity is used to fund the expansion of what many think of as dodgy enterprises. But that is no reason for governments to interfere. I hold no brief for the proliferation of strange and baffling cults, but to select some for special treatment challenges all our beliefs in freedom.

I know something about Scientology. I spend a fortnight down at their headquarters in East Grinstead back in the 1970s. They were seeking UK recognition as a religion because of tax and other benefits, and I was making a television programme about them. I attended a Scientology wedding. There were strange pentangles around the altar, and unfamiliar liturgy calling on alien forces. But the bride wore white, there were bridesmaids and a man in a clerical collar. The followers had the frightening smiles of the passionately devout, but were otherwise civil and indeed normal.

Back at headquarters, I took some of their personality tests and was initiated into the fast track towards "clear" - a system of psychological training (defectors call it brainwashing) that would clear me of troubles lingering from my past and set me on the road to virtue and prosperity. It has much in common with other faiths.

And such new faiths are increasing. In the 20th century, according to the Encyclopedia of American Religions, there were some 1,500 individual denominations within American Protestantism alone. Outside Christianity, Rastafarianism began in the 1930s, Scientology in the 1950s, The Kabbalah movement - a modern take on ancient Jewish wisdom - got under way in the 1990s. Today's emphasis on individual fulfilment means that more of us are shopping around for that particular mix of spiritual enlightenment and gratifying wellbeing that suits our needs. We can expect more to arrive by the hour, as followers of orthodox faiths despair of their homophobia and misogyny. We had better get used to it.

What I deplore is the current rush to ban things of which you don't approve. Banning should be the last resort. Otherwise the ban itself scatters the gold-dust of subversion on previously trite pursuits. It's reported that among young tearaways an Asbo is now a badge of honour. In the time of US prohibition, speakeasies, often run by criminal syndicates, attracted the modish and reckless in search of a drink. Who can doubt that the looming smoking ban, so rigorously punitive, won't prompt defiant attempts to get round the rules and indulge the wickedly nicotine-addicted. Cigar smoke-easies are now listed on American websites, and people are travelling to American tribal lands where smoking is still allowed.

Banning is an attempt to control the behaviour of people who don't want to be so controlled. When it involves a child, it has the nature of a dare. When it concerns adults it invites secret and devious avoidance. These are not easy outcomes to deal with, and merely knock on the effect of the original ban. When the Catholic church included Joyce's Ulysses and Marie Stopes' Married Love on its Index, literate households kept copies covered in brown paper on top shelves. Humanity is not easily dragooned by its own kind claiming moral superiority.

When there is a broad consensus, of course, we use the law. But there is a limit to its effectiveness. Next week's smoking ban is pushing legal controls to the very limit. What will be next? Watch out parents who smoke at home: your children could be taken into care. Obese children, likewise. The only limit to the increasing interference in our personal lives will be the capacity of the police and the courts to cope.

And we are rapidly reaching that point. This week, the new Criminal Justice Bill (the 55th since 1997) announced 19 new offences to add to the 3,000 crimes created in the 10-plus years of Tony Blair's prime ministership. No wonder prisons are choc-a-bloc, police recruitment stalled and courts running behind. Better perhaps to stop short of any further bans. The system clearly can't bear it. And neither can we.

joan.bakewell@virgin.net