Demonstrators at the G20 protests in London, April 2009, found themselves subjected to mass detention at a Climate Camp protest. In the case of R (on the application of Joshua Moos and Hannah McClure) v The Commissioner of the Police of the Metropolis the English High Court has found that police unlawfully detained protesters who were acting peacefully, using a tactic known as "kettling". This refers to the containment of protesters in a confined space for a period of time. In order for such actions to be justified, there must be a risk of an imminent breach of peace.
The Court found that at the time the decision to contain the Climate Camp protest was taken, "there was no sufficient apprehended imminent breach of the peace...to justify containment". They so found notwithstanding that they expressed "considerable sympathy" with the police's task. However they held there was no serious disorder or violence at Climate Camp, as compared with sustained disorder and violence at a separate and simultaneous protest which had justified containment. Please click here to view a Human Rights of Ireland blog on the issue.
It is worth noting that the English High Court did not go so far as to hold the act of containment to be unlawful in general. Kettling is a controversial tactic which will come under scrutiny by the Grand Chamber of the European Court of Human Rights in the challenge of Austin & Ors v. the United Kingdom. Ms Austin was a peaceful protester in an anti-globalisation demonstration in 2001 who was contained within a police cordon for over seven hours with no access to food, water or toilet facilities. The Grand Chamber is due to hear this matter on 14 September 2011.