This book outlines the principles behind the international law of foreign investment. The main focus is on the law governed by bilateral and multilateral investment treaties. The book traces the purpose, context and evolution of the clauses and provisions characteristic of contemporary investment treaties, and analyzes the case law interpreting the issues raised by standard clauses. Particular consideration is given to broad treaty-rules whose understanding in practice has mainly been shaped by their interpretation and application by international tribunals. In addition, the book introduces the dispute settlement mechanisms for enforcing investment law, outlining the operation of State vs. State and Investor vs. State arbitration. Combining a systematic analytical study of the texts and principles underlying investment law with a jurisprudential analysis of the case law arising in international tribunals, this book offers an ideal introduction to the principles of international investment law and arbitration.