The question of how to respond to violations of the laws of armed conflict has been a key issue in international relations, and in the politics of many countries, in the 1980s and 1990s. The formal mechanisms of implementation provided for in treaties have for the most part not been effective. This body of law tends to be referred to in fashionable and contemporary terms as 'humanitarian law'. The less flawed but older term 'laws of war' is preferred here. Some constraints, but only some, on violating these laws can be carried out through such provisions and punishments as envisaged by international legal agreements, criminal trials, human rights law, compensation, national commissions of inquiry, and other acts of individual countries, regional organizations and alliances. The second part of the article, to appear in the September issue, will examine the roles of the UN in its implementation of the laws of war.