BIG SISTER IS WATCHING US

THE FIRST woman I slept with kept pornography under her bed. The small, mild stack - Penthouses and Playboys, thrown in among innocuous Titbits - had been given to her by an older man who sometimes drove her home, and who hoped that by learning a thing or two about human sexuality she might start fancying him. It didn't work. I don't think she fancied me much, either, but knowing the magazines were there gave my trips to her room an extra frisson: on the bed might be all adolescent fumbling and failure, but underneath lay fleshly amplitude and pneumatic bliss.

What my inamorata's attitude to porn was I could never work out. Sometimes she'd mock the mags, and speak cynically of the weakness and predictability of men in finding this sort of stuff interesting. But she kept them rather than handing them back, and also presumably looked at them in private - as I did, when she wasn't there. Perhaps, male-oriented though they were, they even aroused her. Desire, I grasped, was a mysterious business. There were no rules. Who was to say?

There are still no rules. But there are laws, and some pundits argue that there should be more. Over the last decade, fundamentalists who want to ban pornography because it's immoral, or simply embarrassing, have been joined by feminists who regard it as abusive to women. Politics can make strange bedfellows, and this particular two-backed beast - a union of, as it were, the Whitehouse brigade and the daughters of Greer - is one of the oddest creations of our age.

What drives it is a belief that Man, or man, is an unbridled phallus, a prick on legs - a fallen creature, at his most fallen when erect. He is wily, and harbours dangerous wares. Showing porn to him is like saying "Kill" to a trained guard dog. Women need protecting from him. Those, like my poor inamorata, who have slipped into his clutches and acquired a taste for his porn habits deserve only contempt. They are his dupes - sell-outs, Uncle Toms, collaborators, scabs, fellow-travellers, tools, pawns, house niggers, puppets, suckers.

In the US, the lobby to restrict sexually expressive material has been more influential than here. Prominent among the "pro-censors" are the law professor Catherine MacKinnon, author of Only Words, who has said that "if pornography is part of your sexuality, then you have no right to your sexuality", and the novelist and polemicist Andrea Dworkin, author of Letters from a War Zone ("For fun they rape us or have other men or sometimes animals rape us and film the rapes and show the rapes in movie theaters or publish them in magazines"). Under the sway of such arguments, various institutions and state departments in the US have not only confiscated porn mags and videos from shops, but banned sex manuals, removed safe sex posters and withdrawn classical paintings (Goya's "Nude Maja" was one casualty of such edicts). Professors whose courses have been deemed guilty of having a sexual content have been suspended. A new age is here, a "culture of complaint" as Robert Hughes has called it, a tyranny of piety. Big Sister is watching us.

In Defending Pornography, Nadine Strossen has written a passionate attack on the censorship lobby, an indignant liberal defence of threatened freedoms. President of the American Civil Liberties Union, and (like Catherine MacKinnon) a feminist and law professor, she does not believe pornography is harmful, sees no evidence that it leads to greater violence against women, and thinks it has been given too high a priority on the feminist agenda while other, more important battles remain unfought. Her argument - why women should defend pornography - may seem a little perverse at first. But historically it makes sense. Laws against freedom of sexual expression have always been antithetical to women's rights. Censorship is not an answer.

The mistake of the MacDworkinites, as she calls them, is to treat sex as inherently degrading to women. In their gulag of sanctimony, all men are beasts and all women victims. (Dworkin: "Intercourse with men as we know them is increasingly impossible"; MacKinnon: "Compare victims' reports of rape with women's reports of sex. They look a lot alike...") But sexual expression can't be equated with sexism. Don't women feel desire, too, and doesn't some pornography cater for that? Forty per cent of porn video rentals in the US are now by women. It's condescending to call them dupes, and a patriarchal stereotype to suppose they need protecting from their own desires.

This is an issue, not just about porn, but about equality, or equivalence, of desire. Every Jill must have her Jack, and if that's not possible, she has as much right to jill off (a phrase new on me) to her material as he has to jack off to his. It's also an issue about defining women's sexuality - what they willingly choose, rather than are coerced, to do. If you think women perform fellatio, say, only to please their man, you will be in MacDworkin camp; if you think they can derive their own pleasure from it, in Strossen's.

To Strossen, the MacDworkinite line on gender difference isn't a defence of women but a betrayal of them - a tale of female weakness and male potency. Take the attempt to protect women from harassment in the workplace, by asking employees to refrain from all comment and imagery of a sexual nature. In 1993, for example, the University of Nebraska ordered a graduate teaching assistant to remove from his desk a photograph of his wife in a bathing suit, claiming that it created "hostile-environment sexual harassment of female faculty, students and staff".

How can measures like this possibly serve the interests of women, Strossen wonders. She attacks "the notion that all expressions, looks or gestures that recognise a woman's sexuality are somehow antithetical to her personhood". Equality is one thing; treating women like children, or servants, in front of whom certain words may not be spoken, is another. How are women to reach the upper echelons of businesses and institutions if the men currently in positions of power are made paranoid about how to interact with them - if a climate is created where male and female colleagues can't ever relax, joke or talk dirty without the fear of legal comeback?

The erotophobes have also misunderstood the meaning of sexual images, Strossen believes. Male violence against women, for example, plays little or no part in most porn videos. Even if it did, why assume the incitement of a simplistic monkey-see, monkey-do reaction in the viewer? MacKinnon might equate a description of rape with the act itself, but (here is a breezy dismissal of the stringencies of Only Words) images are not the same as deeds. What about women who have rape fantasies, or enjoy watching them acted out on film: are they in need of a shrink? Or might such fantasies fulfil a healthy function, since the point about dreams of subordination (men have these too) is that they exempt us from the responsibility and pain we might feel in the real circumstances?

The nuances of sexual imagery, Strossen argues, are notoriously difficult to interpret. One person's turn-on is another's detumescence. She gives the example of Lina Wertmuller's "artistically acclaimed" film, Swept Away (it actually sounds pretty terrible), the story of a rich, teasing, haughty socialite on a yacht, who, after being marooned on an island, gets her sexual come-uppance from a crew-member she has previously taunted. Women have reacted very differently to this film: who is to decide for them if it is ideologically sound? And what difference would that make to their response, anyway? Even the crudest erotica raises complex questions of correctness. Take the stereotype of the "come-shot" - the man ejaculating on the body of a woman, who then smears the semen over her skin and licks it. A misogynistic archetype? Or a scenario which empowers women, since the male ejaculation, usually hidden from them, is here forced into the open? An aggressive image? Or one which shows men striving to become like women (the semen as milk, the male as mother to his suckling lover)? Hard to say. And a matter, therefore, on which no one should legislate.

Strossen's biggest argument with her opponents is that they are trying to legislate - and to stifle speech. She sees this as a threat to the First Amendment. She does not buy their distinction between "criminal" and "civil" suits - if anything, fear of a civil action may be more off- putting to a writer and artist who would like to make sexual expression part of his or her work. She describes the effects of MacDworkinism in Canada, where gay and lesbian bookshops have suffered more at the hands of busybodying Customs officials than have the hard porn merchants.

Defending Pornography is a spirited and well-documented book. But it does have weaknesses. One is that Strossen romanticises porn. All's rosy in her garden of love. Porn is educational, egalitarian, pluralistic, affirmative, health-giving, the resource of the shy, sad and disabled, the safest form of safe sex. Sex industry workers enjoy conditions "less dangerous and onerous than those experienced by the women who labor in mills and on assembly lines". Above all, porn - like high art - challenges establishment values. Every third-rate porn hack who's tried to make a quick buck is welcomed under Strossen's umbrella of serious creators and brave spirits. It's hard to reconcile this view of noble rebellion with the kind of bland Euro-porn to be seen on late-night channels or replayed in hotel rooms. Those pumping bums haven't much to do with radical chic.

As well as being soft on the soft stuff, Nadine Strossen underestimates the nastiness of the hard. Whether Linda Lovelace participated willingly in Deep Throat or not, there's no doubt that some women are forced by economic necessity to pose or act in ways that encourage ugly attitudes to women. "The only thing pornography is known to cause," Gore Vidal has said, "is the solitary act of masturbation." A comforting thought. But even that solitary act can have a social outcome, as the semen-glued pages of public library books testify. And it seems blind or wilful of Nadine Strossen to deny that porn can sometimes have more serious consequences - at the least, a tendency for some men to see women as objects, to be used with brutality and force.

Catherine MacKinnon goes much further. She thinks porn incites men to rape, murder and child abuse, and quotes the case of Thomas Schiro, whose defence for having sexually assaulted and murdered a woman in Indiana in 1981 was that he would "get [so] horny from looking at girly books and watching girly shows that I would want to go rape somebody". Nadine Strossen rightly argues that acceptance of such a defence - "porn-made- me-do-it" - would remove essential notions of culpability and intentionality. She cites counter-evidence to show that where porn has become more freely available - Japan, Scandinavia - the number of violent sex crimes has gone down. She makes her case persuasively: it you ban all ideas and images which might prove unsafe, almost nothing worth having will be left. I just wish she weren't quite so cheerful about dirty mags and movies, so excitable about the wonderfully infinite variety of the human imagination. A bit of gloomy, post-coital scepticism would have done no harm.

As she battles it out with her two adversaries (though one of her complaints is that in the real world the other two won't meet and debate with her), you begin to appreciate their different strengths. Nadine Strossen has the best command of the relevant information and research. Catherine MacKinnon has the keenest intellect. Andrea Dworkin is the liveliest phrase-maker ("romance is rape embellished with meaningful looks", "in seduction the rapist bothers to buy a bottle of wine"). You also hear the echo of other, older, bigger wars in American culture: Redskin v Paleface; Pioneer v Puritan; Individual Freedom v Public Law. The signs, in the current censorship battle, are that the ground is shifting, and that MacDworkinism has begun to lose the argument. But to the punters with their books, mags, videos, satellite channels and PCs, it won't make much difference. Legal or not, under the bed or on the Internet, spiced for nerds or groomed for women, porn is here to stay.

! 'Defending Pornography: Free Speech, Sex and the Fight for Women's Rights' by Nadine Strossen is published on 15 February by Abacus at pounds 7.99