Treaties (also called covenants, protocols, acquis, conventions, pacts or charters) are international agreements between states and/or international organizations. Treaties are primary sources of international law. For a guide to finding treaties, click here. Conventional international law is based on consent of state parties and as such the treaty applies only between those parties. In determining treaty application, watch for state party reservations, understandings and declarations which can transform that state's obligations. Treaties only bind nonparties when they form the basis for customary international law. Customary International Law is formed when states consistently act in a certain way (state practice) out of a sense of legal obligation (opinio juris). State practice includes domestic legislation, regulations, treaties, judicial decisions, diplomatic communications, NGO and IGO practice (for example General Assembly Resolutions and state voting practice). Look at judicial decisions and executive communications for evidence of opinio juris. A state may escape the application of customary international law by being a persistent objector.
Some treaty databases available on LexisNexis:
Some treaty databases available on Westlaw:
Paper Sources for Major Treaties
Links to Fundamental Treaties
Online Sources for Major Treaties
The websites of major international bodies often display their founding treaties: