Which principle requires World Trade Organization members to treat trading partners equally?

Most-favoured-nation treatment is the World Trade Organization principle requiring members to treat trading partners equally.

Under the principle, if a WTO member grants a trade advantage to one member, it generally must extend the same advantage to all other WTO members. The rule is intended to prevent discriminatory treatment among trading partners and make negotiated concessions broadly applicable.

The phrase is misleading in ordinary language: “most favoured” does not mean giving one country the best special status. It means avoiding favoritism among members. Important exceptions exist, including customs unions, free-trade areas, and certain preferences for developing economies.

Most-favoured-nation treatment is different from national treatment. MFN compares foreign trading partners with one another, while national treatment concerns how imported products, services, or intellectual property are treated after entering a market.