The civil rights group Liberty has won permission for a full High Court hearing to challenge the use of anti-terrorism laws against people protesting outside Europe’s biggest arms fair in London.

Some 144 people were arrested in connection with the Defence Systems Equipment International (DSEI) show in London’s Docklands, which ran for four days beginning September 2.

Arrests had been made on a variety of charges, from flyposting to “conspiracy to commit violent disorder.” Even before the show began, 51 arrests had been made.

Some protesters have taken civil disobedience measures to disrupt the proceedings, which are attended by thousands of top military and government officials from around the world. On September 3, two protesters held up delegates travelling to the show for 40 minutes by chaining themselves to two trains. Protester Mehdi El-Rahdi was eventually freed from the front of the train by police using boltcutters.

Generally, most of the protests were small and confined to demonstrations outside the event. More than 2,600 police and security guards policed the site, including 25 Ministry of Defence police officers, with the total cost of security expected to be more than £1 million.

Liberty says that some police used emergency powers contained in sections 44 (1) and 44 (2) of the Terrorism Act 2000. This is an illegal use of the measures, which the government had claimed in Parliament would only be used in instances where there was good reasons to believe a genuine terrorist threat existed.

Instead, the government was using the legislation to “break up the demonstration, to stop people, to take away their basic right to freedom of speech,” a spokesman for Liberty said.

On September 12, Liberty went to the High Court to seek a full hearing on the legality of the police’s action, using as its test case Kevin Gillan, who was stopped, searched and served with a section 44 warrant by police officers. Gillan’s arrest form confirms that he was stopped under the Terrorism Act and that he was “involved in protests.”

Having initially denied that anyone had been arrested under the act, police later admitted that some officers had used the legislation to stop and search protesters “where they deemed it necessary,” as a Scotland Yard spokesman told the BBC.

The measures had been approved by Home Office, the spokesman said. “We are aware concerns have been raised, and we recognise the importance of dealing with those concerns.

“When appropriate, officers are authorised to use powers available to them under section 44(1) and 44(2) of the Terrorism Act 2000. This is applicable throughout the capital.

“This is not in response to a specific threat, but is part of our high-visibility policing across London.

“We believe these powers have been used by some officers. However, in the main, officers are using powers under section 1 of the Police and Criminal Evidence Act.”

Faced with criticism from all the opposition parties, Home Secretary David Blunkett attempted to portray the issue as simply an operational matter whilst calling on the Metropolitan Police to account for their actions.

“I have asked that the head of the counter-terrorism branch should report back on why it was that they chose to use that particular part of the counter terrorism legislation rather than wider public order legislation,” Blunkett said. “I don’t want to make a judgement until I hear from him what evidence they had at operational level that there was a concern of that sort.”

The defence industry is a massive business in Britain, which is the second largest arms exporter in the world after the US. With annual sales of £17 billion, the British government is the UK defence industry’s largest customer, placing orders last year worth £13 billion. Though the arms fair is privately run, the government contributes £250, 000 towards it, decides who should attend and provides military personnel to help run the show.

Whilst its economic importance and political sensitivity would ensure the event was highly policed, the use of anti-terror measures against protesters seems to be more of a case of testing the water for future use.

Without any notice whatsoever, much less an explanation, the Metropolitan Police placed the whole of London under emergency powers, supposedly on the grounds of “high-visibility” policing. It then proceeded to arrest individuals under anti-terror legislation, despite knowing that they were not involved in terrorist offences and despite other grounds for arrest being available.

Liberty’s director Shami Chakrabarti said that Blunkett’s request for an explanation from the Metropolitan Police was simply passing the buck and challenged him to explain how the use of such powers had been authorised.

“These are very draconian measures, and the home secretary needs to come out and say why he has endorsed them,” she said.

“If the whole of London has been declared a place where these powers can been used, why have Londoners not been told about it officially?

“This is not a matter of operational policing, as the home office has suggested today.

“It is an extreme constitutional measure. By passing the buck to the police, he is turning counter-terrorism measures into a political football and shirking his constitutional responsibility. The legislation is clear that the buck stops with the home secretary.”

Liberty’s application for a judicial review will begin after October 1.