The judgment was based on a case brought before the courts by protesters who were kettled in Oxford Circus in central London for over seven hours during the 2001 Mayday anti-capitalist protests. More than 1,500 were detained without access to food water or toilet facilities by police for a fear of ‘beach of the peace’ despite there being no major outbreaks of violence during the day of protest.

Previously the police did not have the power to detain people against their will unless it was for arrest purposes. The European courts have now given the police the green light to deprive individuals of their liberty – even if they have done nothing illegal or committed a crime, for long periods of time under ‘public order’ tactics.

David Pannick QC, who represented the police argued “kettling” did not violate the human rights code. He said the code’s guarantee of liberty – except for individuals lawfully held in criminal matters – was not meant to concern “mere restrictions of movement”.

The court stated: “The police had imposed the cordon to isolate and contain a large crowd in dangerous and volatile conditions. This had been the least intrusive and most effective means to protect the public from violence. Although the police tried to start dispersing the crowd throughout the afternoon, they had been unable to do so as the danger had persisted.”

Adding: “Even by 2001, advances in communications technology had made it possible to mobilise protesters rapidly and covertly on a hitherto unknown scale. Article 5 did not have to be construed in such a way as to make it impracticable for the police to fulfil their duties of maintaining order and protecting the public.”

The judges voted 14-3 in favour of the police, re-enforcing the 2009 House of Lords verdict that kettling as a crowd control measure was “necessary, proportionate and lawful”.

It was the first time the court in Strasbourg had been asked to rule on kettling.