“JUST because you lop off your dick and then wear a dress doesn’t make you a fucking woman,” believes Germaine Greer, an Australian-born feminist and controversialist. Her views on transsexuals have persuaded more than 2,800 people to sign a petition calling for her to be banned from giving a talk (on a different subject) at Cardiff University next month. On October 26th Ms Greer indicated that she would cancel her appearance rather than be “screamed at and have things thrown at me”.

It has been a busy term for student censors. Oxford’s student union banned No Offence, a magazine featuring stories defending colonialism and other controversies, from being distributed at its freshers’ fair. Manchester’s union banned two journalists from taking part in a debate on free speech because of their own “transphobic” views. And the Cambridge Union, a debating society, held a members’ referendum (successful, in the end) on its plans to allow Julian Assange of the whistle-blowing WikiLeaks site to speak via video link.

Such challenges to debate are now common. A free-speech index compiled in February by Spiked, an online magazine, found that 135 bans of various sorts had been imposed within university campuses in the previous three years: on songs with offensive lyrics; newspapers that print topless photos on page three; and speakers whose views on everything from abortion to Zionism were considered beyond the pale.

The most zealous censors are not the university authorities but students themselves. Many unions now operate “safe space” policies, imported from American universities, which aim to create environments in which no student feels threatened by ideas deemed harmful. The mere act of inviting Mr Assange, who is accused of rape in Sweden, to appear via video has taken a “visceral, physical toll” on victims of sexual violence in Cambridge, says Charlotte Chorley, the student union’s women’s officer.

Others say the complainants are merely offended, not harmed. “Offence is a natural part of a liberal society,” argues Edgar Häner, an organiser of the Manchester event that was shut down. “Saying that freshers can’t handle [our] material is patronising,” says Lulie Tanett, a co-editor of No Offence.

The government is curbing speech on another front. New rules came into effect in September requiring universities that host speakers “with extremist views linked to terrorist groups” to ensure that they are challenged by others. If “in any doubt that the risk cannot be fully mitigated [universities] should exercise caution and not allow the event to proceed,” official guidelines say. The original bill, watered down in the House of Lords, had proposed that universities ban all speakers with extremist views, on pain of contempt-of-court charges. The National Union of Students, perhaps surprisingly, is dead against the crackdown.