This paper critically examines the potential of prisoner litigation in Canada to shed light on what U.S. Supreme Court Justice Anthony Kennedy has called “the hidden world of punishment.” It considers whether prisoner’s rights litigation can act as a meaningful legal check on the growing punishment agenda in Canada. The paper begins with a brief description of some aspects of the punishment agenda before moving on to consider case law under the section of the Canadian Charter of Rights and Freedoms which speaks directly to punishment and its limits, the section 12 right to be free from “cruel and unusual treatment or punishment.” A dominant strand in the section 12 case law has been the minimal impact the section has had in limiting the proliferation of mandatory minimum sentences in recent years. This paper considers another strand of section 12 case law which has received little attention and which presents a different kind of challenge to the punishment agenda, namely section 12 review of prison conditions and the treatment of prisoners. The paper concludes with some thoughts on the limitations and potential of Charter litigation in the prison context.