This chapter provides an overview of how the modern understanding of the norm against torture and inhuman and degrading treatment came to be and discusses its subsequent gradual transformation. Taking the Convention drafters’ stated intentions as a baseline, it traces the development of the norm through several landmark judgments. Relying on legal analysis, I note that the bounds of the norm against torture and inhuman or degrading treatment were initially limited in order to appease member states during the time of the old Court. Although the old Court had progressive instincts, it could not always act on them. It could expand the norm only when it was safe to do so – when the stakes were low and there was an emerging consensus around an issue. Such constraints influenced the way the norm against torture and inhuman or degrading treatment developed in the early days of the European human rights regime. However, despite such hesitations, the old Court made a colossal contribution to the norm’s evolution, planting the seeds of progress by introducing the living instrument principle in Tyrer v. the United Kingdom.

While it is widely accepted that foreign relations law determines the domestic competences for international treaty-making and the place and status of international law in the respective domestic systems, the more informal and contextual influence of foreign relations law on international treaty making is understudied. With reference to the US position on the Paris Agreement on Climate Change, I argue that domestic foreign relations law at times shapes the negotiation process by limiting possible outcomes. At the same time domestic foreign relations law might be used as a bargaining tool to push other states to sign onto a particular negotiating position. Even though foreign relations law can unfold this power only under very specific circumstances, the example demonstrates potential effects of domestic constitutional design for the international legal system.