The House of Lords stated and applied the following principles:

1. personal liberty is among the most fundamental of rights;

2. although national security is a matter of political judgement for the executive and Parliament, a court is required, when Convention rights are in issue, to give effective protection by adopting an intensive review of whether such a right has been impugned; and

3. the courts are not precluded by any doctrine of deference from examining the proportionality of a measure taken to restrict such a right.

The Court of Appeal had to decide whether the police had been justified in depriving the claimants of their liberty, by cordoning them within an area for seven hours along with over 1,000 protestors, on the ground that it was necessary to prevent a breach of the peace.

In extreme and exceptional circumstances it is lawful for the police to contain demonstrators and members of the public caught up in a demonstration even though they themselves do not appear to be about to commit a breach of the peace, where it is necessary to prevent an imminent breach of the peace by others, and no other means would achieve that.

The question was whether a custody officer was entitled to detain an arrestee whilst he sought guidance from the Crown Prosecution Service under s 37A PACE on how to proceed with the charges.

Section 37(7) PACE dealt comprehensively with the alternatives available to a custody officer who had determined that he had before him sufficient evidence to charge an arrested person; that those alternatives did not include a power to postpone the charging decision for the purpose of obtaining advice from the Crown Prosecution Service without admitting the suspect to bail; that such a power could not be inferred by reference to guidance issued by the Director of Public Prosecutions under s 37A, which was not referred to in s 37(7) which was required to be consistent with and limited by the alternatives found in that subsection.