This is Louis Henkin's classic book, long out of print, in a much-anticipated new edition. Reconceived, reorganized, and updated, this work remains a model of clarity. This new edition is essential reading for all those interested in understanding the United States and its place in world affairs. Professor Henkin takes the reader through the mysteries of the US Constitutional system as it governs US foreign relations. He explains how the US Government acts on the world scene - respective authority of the President and Congress in making foreign policy and conducting foreign relations, conflict and co-operation between them in determining the use of military force, and US policy on arms control, on the sale of arms, on trade, on financial assistance, on human rights. He explains where US treaties stand in US law and policy; the role of the courts in foreign affairs; US policy on the United Nations and other organizations, on international tribunals, what the Constituion requires in respect for individual rights within the US and beyond. Every reader will be able to follow and enjoy the text. For those who are interested there are many pages of rich, scholary notes.