The focus of this Article shall be upon the Eighth Amendment of the United States Constitution and s. 12 of the Canadian Charter of Rights and Freedoms, both of which prohibit “cruel and unusual punishment”; and their effect on mandatory criminal sentencing (via penal statute) in the two countries. The Article shall begin by briefly explain the differences between the jurisdictional application of criminal justice in the United States and Canada. The Article will next present and explain the American Eighth Amendment approach to the constitutionality of mandatory criminal sentencing and contrast this to the Canadian s. 12 approach to the constitutionality of mandatory criminal sentencing. The contrasting of the two national approaches will underlie the main argument of the Article, namely that if one’s concern is the fair and proportionate application of justice, then the Canadian approach to reconciling the constitutional prohibition against “cruel and unusual punishment” and the application (through penal statute) of mandatory criminal sentencing is the superior one. The Article shall conclude with a discussion of the possible reasons for the differing national approaches to mandatory criminal sentencing.