This research addresses the issue of punishment from the perspective of national constitutional law integrated with European human rights law. Part I argues that the transformation of criminal constitutional law, under the influence of ECtHR jurisprudence, represents progress in the historical process of the constitutionalization of punitive power. This conclusion is supported through a comparison of classical constitutional philosophy on punishment with the different interpretive approaches to criminal constitutional law developed during the 20th century (traditional, constitutionalist, and EHR approaches). Part II argues that, despite the positive effects of supranational harmonization, the constitutional status of punishment should remain formally autonomous from ECHR law. Not only is no existing theory of relations between legal orders suitable to justify total integration, but such integration would also risk reducing the normativity of the “social aspects” of criminal constitutional law, which are already underdeveloped compared to the “liberal aspects”. In the Conclusion, the fundamental elements of an alternative interpretive approach to criminal constitutional law, which better meet the needs of both ensuring maximum constitutionalization of punishment and facilitating supranational integration, are developed. Based on a constitutionally grounded, substantive, rights-based, and inclusive approach to all constituent ideologies, the Constitution could be interpreted as providing a unified model of discipline for all forms of exercise of punitive power (except disciplinary sanctions, distinguishable from an institutional perspective). This model is characterized by a reserve of law of varying intensity, strict scrutiny of the Court on the constitutional justifiability of punishment, the extension of the scope of application of the principles of guilt and re-education, and full development of collective guarantee aspects of classic constitutional criminal law principles (positive obligations to punish and guarantees for non-transferability of punishment), as well as those derived from Art. 3 Const. (proportionality of punishment to the material conditions of the offender).