When my father was a student at the University of Cape Town in the 1970s, the university went to court to prevent the police coming onto campus during political demonstrations.

Yesterday Michael Chessum, the president of the University of London students’ union, was arrested on suspicion of an offence under Section 11 of the Public Order Act – failing to notify the police of a public procession. The procession in question was a demonstration the previous day of maybe 200 students, on the pavement outside the students union, around the perimeter of Senate House and in the Senate House car park.

They were protesting against the decision of University of London management to disband the union, leaving them with no London-wide representative body. 'Some of the services currently provided by ULU will be run commercially, by university management, rather than by and for students. There will no student oversight or democratic control, and the campaigning function of ULU will cease to exist,' Daniel Cooper, ULU's vice-president, told me. 'This decision has been taken by the university without consulting students, and shows their contempt for the notion of a democratic university.'

Protesting on campus has been effectively banned by the university since the summer, when a student was arrested on suspicion of criminal damage for writing a slogan in chalk in support of a university cleaners’ campaign for better working conditions. A few weeks ago a demonstration in support of the campaign was kept off campus – security staff locked the gates – until some protesters climbed over the gates and others found their way in through unmanned side entrances. University staff filmed the protest from a balcony overlooking the car park. They also took footage of Wednesday’s demonstration.

Many students seem to think that the university colluded with the police in Chessum's arrest, given that he was arrested immediately on leaving a meeting with Chris Cobb, the university’s chief operating officer. Ten days ago Cobb wrote to Chessum and Cooper, advising them to 'review your personal and institutional responsibilities and liabilities in leading protesters into physical danger and unlawful action.' Cooper says that in light of Chessum's arrest the message now sounds like a threat.

A university spokesman strongly denied that they had any prior knowledge of the arrest, but said that they would share information, including video footage, with the police if requested. He said that the footage itself is a necessary precaution in case staff are subject to verbal abuse or physical harm. Apparently a security guard went to hospital last week after being injured trying to hold a gate closed – though it wouldn't have happened if students weren't being kept off their own campus. The spokesman also told me that a protester had been arrested on suspicion of assault following a previous demonstration – a fact the university trumpeted in its statement on demonstrations last month – neglecting to mention that the person in question was released and the charges dropped.

As far as I could make out, the only people in physical danger on Wednesday were the student protesters being dragged off their own campus by police. The head of security at Senate House lent the police a hand. There are photographs of him throttling students – students for whose ‘security’ he is presumably responsible – and pulling up a female student's top as he drags her out of the Senate House car park.

Chessum was released from Holborn Police Station at eight o'clock last night, having been held for around seven hours. He hasn’t been charged yet – and it would be hard to get a conviction since the protest didn’t even leave the pavement – but his bail conditions will make Chris Cobb smile: he’s forbidden from engaging in any protest on any university campus or within half a mile of any university. Similar terms were imposed on anti-fascist protesters arrested in Tower Hamlets in September, who were bailed on condition they didn't 'engage in demonstrations within the boundaries of the M25 where the English Defence League, English Volunteer Force or British National Party are present'.

Chessum's treatment is consistent with a larger pattern: it is now routine to arrest and bail political protesters as a way of preventing them from engaging in lawful protest. Such conditions do not reduce the risk of reoffending – their stated purpose – but are instead designed to curtail dissent.