Sussex University was forced to drop action against four students who led campus protests yesterday when the chair of its disciplinary panel was found to be biased.

Top human rights lawyer Geoffrey Robertson QC proved Professor Michael Davies was not impartial and forced him to step down.

After the hearing was abandoned, Mr Robertson and the students went outside to celebrate with supporters who had braved the rain to stage a solidarity rally.

Mr Robertson told the crowd: "If these students had been suspended, disciplined, or even fined, that would be a very bad precedent for universities across the country."

The four defendants and another student were suspended for taking part in a week-long occupation last year in protest at the privatisation of campus services.

And they could have been thrown off their courses permanently at the hearing.

Final-year law student Michael Segalov said the presence of a leading lawyer showed how much was at stake in the "kangaroo court."

He said: "I believe our rights to freedom of speech and assembly are being illegally attacked, as do all of our supporters.

"The role of the public university is to encourage critical thinking, and the administration at Sussex seem to oblivious to this."

Sussex University didn't respond to a request for comment.

The Star understands that university bosses have scrapped the current disciplinary procedure but are considering establishing a new panel.

The victory comes as a boost to six Birmingham University students who face expulsion after occupying the university's council chambers in November.

Birmingham Guild of Students vice-president Hattie Craig was one of two students taken to court by the university over the sit-in.

Now she is among students being subjected to interviews ahead of a discplinary panel.

She said: "They would read out witness statements and things and we were expected to respond on the spot. They are trying to make you slip up."