25. Goal of Part I – This Part of the book aims to establish the evaluative and normative framework. As was explained in the introduction (see nos 12–13), the focus of this book is on measures that directly impact the physical liberty of people. Within the framework of the ECHR, this means that Article 5 ECHR, which protects the right to liberty and security, is of paramount importance. However, this is not the only relevant Article. Article 2 of the Fourth Protocol to the ECHR protects the freedom of movement and also directly relates to people's physical liberty.

26. Article 5 ECHR – Article 5 of the ECHR reads:

1. Everyone has the right to liberty and security of person. No one shall be deprived of his liberty save in the following cases and in accordance with a procedure prescribed by law:

• (a) the lawful detention of a person aft er conviction by a competent court;

• (b) the lawful arrest or detention of a person for non-compliance with the lawful order of a court or in order to secure the fulfilment of any obligation prescribed by law;

• (c) the lawful arrest or detention of a person effected for the purpose of bringing him before the competent legal authority on reasonable suspicion of having committed an offence or when it is reasonably considered necessary to prevent his committing an offence or fl eeing aft er having done so;