Passage or principleWTO Agreements; investment treaty doctrine; Rio Declaration
International economic law is no longer only about lowering barriers. WTO law rests on disciplines such as most-favoured-nation treatment, national treatment, tariff bindings, and dispute settlement between members. Exceptions allow regulatory space but are controlled by legal tests, including chapeau analysis under GATT Article XX. Investment treaties protect investors through standards such as fair and equitable treatment and protection against uncompensated expropriation, yet modern treaty practice increasingly preserves the host state's right to regulate. Environmental law adds principles such as prevention, precaution, environmental impact assessment, and sustainable development. The modern challenge is to prevent discrimination and abuse while preserving legitimate public regulation.