International Investment Agreement
An International Investment Agreement (IIA) is a treaty concluded between states that requires the state parties to provide foreign investors and investments certain standards of treatment and protections. IIAs commonly also enable foreign investors to sue the state in which they are making the investment directly in international arbitration for breach of the treaty.
Source: CCSI: The Impact of Investment Treaties on Governance of Private Investment in Infrastructure (2014)
See also:
IISD's Investment Treaties and Why They Matter to Sustainable Development: Questions and answers
UNCTAD's International Investment Agreement Navigator
UNCTAD’s glossary for a list of key terms in IIAs.