This thesis aims to examine a selection of the standards identifiable in the published work of the European Committee for the Prevention of Torture and Inhuman or Degrading Treatment or Punishment ("the CPT"). Part I commences with an examination of the mandate and modus operandi of the Committee, followed by an exposition of the two fundamental principles - of confidentiality and co-operation - which inform its work. The CPT's standard-setting work is introduced by means of an examination of its evolution and rationale, the purport of standards set and the ways in which such standards find expression. Part II concerns CPT precepts on police custody. It begins with an examination of the CPT's "three fundamental safeguards against ill-treatment": the rights to notify a third party of the fact of one's detention, of access to legal advice and to a medical examination by a doctor of one's own choosing. It then considers, in turn, the duty to inform a detainee of all his rights; the conduct of police interrogations; the electronic recording of interviews; the maintenance of custody records; and police complaints and inspection procedures. Part III is devoted to a number of matters considered under the umbrella term "imprisonment". It begins with a detailed examination of the phenomenon of prison overcrowding, its effects on detainees and the prison environment, and policies designed to eradicate it or at least mitigate its effects. There then follow two sections on recourse to and safeguards attending, the use of force and/or instruments of restraint and solitary confinement in places of detention (which places include, for the sake of completeness, police establishments, immigration detention centres, psychiatric establishments, etc.). Part IV attemptst o draw everything together, to assess the impact of CPT standards on national criminal justice and penal policy and to consider ways in which that impact might be enhanced.