Chapter 5 considers the surveillance of potential terrorists and their arrest, including the force that may be employed to do so. Once in custody, criminal suspects should be interviewed without the threat or use of physical coercion in order to gather evidence to decide whether or not it is right to engage a prosecution for terrorism (or other criminal offences). In certain circumstances, control orders or similar judicial decisions may limit the actions at large of an individual suspect with a view to protecting the public. Most controversial of all, preventive detention by the State may sometimes be made where an individual has been convicted of no crime and is not being held on remand with a view to future prosecution. The chapter addresses these issues in turn considering the treatment of terrorist suspects in accordance with fundamental human rights.