The need for imminence or immediacy of a threat to peace as a prerequisite for kettling. The state should not lightly infringe the freedom to protest, and proper scrutiny of any decision to do so is the hallmark of a free society.
Kettling involves the containment of crowds of demonstrators within a limited area. It is a controversial police tactic and its lawfulness has been the subject of several appellate court decisions. R (on the application of Moos) v Commissioner of Police of the Metropolis  EWCA Civ 12,  All ER (D) 83 (Jan) is the latest decision to examine the legality of the tactic, and refines the law still further.
The starting point for any analysis of kettling is Art 5 of the Human Rights Act 1998 (HRA 1998). This provides a right not to be deprived of liberty except in certain well-defined situations and is an absolute right. Thus, on the face of it, the containment of demonstrators will be a breach of Art 5. Hence, court decisions have focused on the exceptional circumstances in which the state will have lawful justification to employ the tactic.
Austin v Metropolitan Police Commissioner  UKHL 5,  3 All ER 455 was a claim by a demonstrator who attended anti-capitalist protests in London. She challenged kettling under Art 5 and also claimed for false imprisonment. The judge at first instance held that the containment was justified under Art 5(1)(c), as the police reasonably believed that all those within the cordon were about to commit a breach of the peace. Also, there was a policy to release anyone caught up in the protest accidentally or who needed medical attention. This decision relied upon the factual finding that the police reasonably believed that a breach of the peace was imminent. There was no pre-planned kettle; the police were taken by surprise and had to manage what they reasonably believed could become a violent situation. This “imminent risk” approach was essentially endorsed by the House of Lords in 2009. However, all the judges emphasised that police constraints on demonstrators could only be justified by the need to prevent serious public disorder and violence, and must be reasonable and proportionate. The need for imminence or immediacy of a threat to peace as a prerequisite for kettling had also been emphasised by the House of Lords in an earlier case in 2006 (R (on the application of Laporte) v Chief Constable of Gloucestershire Constabulary (Chief Constable of Tames Valley Police and another, interested parties)  UKHL 55,  2 All ER 529).
So, kettling may be lawful in limited circumstances, but must only be done in the face of an imminent breach of the peace, must be done in good faith, must be proportionate and must be done for no longer than is reasonably necessary.
Moos refines this analysis further. In this case, the Metropolitan Police appealed successfully against a High Court decision that it had unlawfully kettled protestors at the G20 summit in London. There had been two associated demonstrations. One was disorderly to the point of serious violence, the other was peaceful. The police kettled both demonstrations, using barricades to prevent protestors from leaving. Two participants in the peaceful demonstration sought judicial review of the police decision.
Following Laporte, the High Court held that the police had not reasonably apprehended an imminent breach of the peace in relation to the peaceful demonstration and so their action was a breach of Art 5. However, the the Court of Appeal concluded that there was no valid basis for finding that the police’s apprehension had been unreasonable, and therefore the kettling of the peaceful demonstration was lawful. Of course, from a practitioner’s perspective, what the police knew and reasonably believed at the time of the decision to kettle may only become apparent on disclosure, so to that extent Moos arguably makes kettling claims more difficult. Nevertheless, Moos falls squarely within the basic principles set out by the courts in other cases. Peaceful demonstrators were kettled but this was because the police reasonably believed that they would be joined by violent protestors from another demonstration, so the tactic was lawful to prevent an imminent breach of the peace.
A striking feature of Moos is the care with which the actions of the police were scrutinised by the Court of Appeal: nearly 100 paragraphs of close examination of the decisions made on the day by Chief Superintendant Johnson, the officer in overall charge of the operation. Some would say that nitpicking by lawyers makes effective policing very difficult. A better view is that the state should not lightly infringe the freedom to protest, and that proper scrutiny of any decision to do so is the hallmark of a free society. Certainly, the case reinforces that since HRA 1998, the actions of the state will be closely examined by the courts to assess reasonableness and proportionality. It is difficult to imagine this kind of case in a pre-HRA 1998 world.