This chapter assesses the effectiveness of the work of custody visiting, and sets out how it can be measured: it is examined according to five criteria of its regulatory function, to assess principally whether the work made any difference to police behaviour. Custody visiting is found to be largely ineffective: in particular, detainees do not trust the visitors, finding the meetings as being of no benefit to them. Custody visiting is measured against the United Nations standards for monitoring detainees, including the need for expertise, and the chapter finds that the United Kingdom is in breach of these international obligations. The chapter looks at the claims made for custody visiting in the scheme’s official literature, including the claim that custody visiting offers reassurance to the public: this is found to be impossible to assess, but probably false, since so few people have heard of the scheme. The chapter concludes that the comprehensive regulatory failure is likely to be the result of deliberate policy, driven by the strong forces of crime control ideology and the power of the police.