Police adopted an “impermissibly low tolerance to public protest” ahead of last year’s royal wedding, lawyers representing anti-monarchist activists who were pre-emptively detained to stop them protesting it have told the High Court.

The accusation came on the first day of a judicial review hearing into the Metropolitan Police’s handling of public protests, which could have significant implications for how the Olympic Games are policed this summer.

A group of 20 activists, who were among scores searched and detained during or before the ceremony, have asked the court to rule that the Commissioner of Police operated an unlawful policy that violated the fundamental democratic right to protest.

Their lawyers accused the Met of effectively “suppressing anti-monarchist sentiment” yesterday. They hoped the case would be heard in time to influence policing at the forthcoming Jubilee celebrations but Lord Justice Richards, who is hearing the judicial review application in London with Mr Justice Openshaw, said that was unlikely, opening up the possibility of a similarly robust policing plan next week.

Karon Monaghan QC, appearing for 15 applicants, said her clients were all pre-emptively arrested on Friday April 29 2011 when Prince William married Kate Middleton. Their arrests occurred in four separate locations in central London, when police officers said they suspected them of being about to commit breaches of the peace.

Ms Monaghan said those she represented were held at police stations and the signal for their release from custody was “the balcony kiss” of the royal couple.

The case touched upon “the most important of constitutional rights, namely the rights to free expression and to protest, both of which are elemental to a properly functioning democracy”, Ms Monaghan told the court.

In policing the royal wedding, the Met “operated a policy of equating intention to protest, whether perceived or actual, with intention to cause unlawful disruption”.

The commissioner’s lack of tolerance for the protests resulted in the “unlawful arrests of those who were viewed by officers as being likely to express anti-monarchist views”, she said.

It was not being argued that the right to protest was absolute, “it is not but it is recognised as a preciously guarded freedom”, Ms Monaghan said.

A previous direct attack on the Prince of Wales’ car was one of the factors taken into account by the Met when they drew up their plans for policing the wedding, the judges heard.