Civil rights campaigners have launched a legal challenge against the police and Home Secretary David Blunkett over the alleged misuse of anti-terror laws.
Anti-arms protesters experienced tight security
Pressure group Liberty is backing a protester and a freelance journalist who were stopped and searched during demonstrations against Europe's largest arms fair in London's Docklands last month.
Journalist Pennie Quinton and student Kevin Gillan have gone to the High Court to seek a judicial review of the way they were treated on 9 September.
Owen Davies QC, appearing for the two, said it was likely the police were regularly being authorised to stop and search people under the Terrorism Act 2000 without the public being told.
But the Metropolitan Police's counsel argued there were safeguards in place to ensure stop and search powers were not used "willy nilly".
And the home secretary's lawyer said that stop and search had been used lawfully.
Ms Quinton, 32, from south-east London, was so upset at her treatment that she stopped filming the protests.
Demonstrator Mr Gillan, 26, from Sheffield, was stopped and searched by police before protest leaflets were taken away from him.
Mr Davies said: "This is the first time this court has been asked to consider the potentially very widespread and
draconian effects of one of the measures introduced by Parliament under the 2000
He told two judges the Metropolitan Police had searched more than 50 vehicles in one month alone this summer.
And during the arms fair 29 people were searched, although Liberty say they have been approached by more than 50 people.
Mr Davies said Scotland Yard Commissioner Sir John Stevens is misusing anti-terror powers along with Mr Blunkett.
He said these figures represented "a random and indiscriminate interference with people's civil liberties".
He argued police officers were often confused about the use of anti-terror laws.
And Mr Davies said that during the arms fair at London's Docklands in September the police were allowed to stop people on the grounds of "the continuing high threat from terrorism faced by the UK at this time, and London in particular".
He said this was due to two 28-day authorisations.
John McGuinness QC, appearing for Sir John Stevens, said there was no evidence these stop and search powers were being misused.
He said they were necessary "to deal with the ultimate threat to every single one of us" posed by terrorism and there was a delicate balancing act to maintain.
Officers were encouraged to avoid knee-jerk reactions.
The powers would never be used against "the little old lady going to buy her
bag of boiled sweets at the newsagents".
He continued: "The greater good of everybody in these particular circumstances overcomes the individual right of any one person who does have the inconvenience of being stopped and searched."
Philip Sales, for the home secretary, also argued the powers had been used lawfully.
The decision had been taken to use stop and search powers following expert assessments of the threat posed
by terrorist activity, and the risk that that threat would become a reality in
Outside court, a Metropolitan Police spokesman said section 44 powers had been authorised by an assistant commissioner for the Metropolitan Police area "on a repeated basis" since 19 February 2001 with each case confirmed by the Home Office.
The hearing was adjourned until Friday.