This chapter discusses the development and current state of international investment law, which encompasses international finance law, international trade law, international investment law, and regional economic trade agreements. Recent progressions in the area of international financial law, international trade law, and investment law demonstrate that other areas of international regulation have a decisive influence on international investment law. Moreover, international investment law is more increasingly focused on development concerns. International investment law is currently going through an exciting phase in its development. It has now become one of the fastest changing areas of international law with exciting and far-reaching implications for both investment-receiving and investment-exporting countries, thanks to enterprising claimants and innovative interpretations and expansive approaches adopted by international investment tribunals. This chapter seeks to capture the law and the recent trends in both State practice and jurisprudence in this area of international law.