In WTO, what principle requires equal treatment for all trading partners?

In the WTO, the most-favored-nation principle requires equal treatment for all trading partners. In practice, a member that grants one WTO member a trade advantage generally must extend the same advantage to all other WTO members.

MFN is one half of the WTO’s core non-discrimination rule. The other half is national treatment, which generally requires imported products to be treated no less favorably than comparable domestic products after entering a market. MFN instead compares one foreign trading partner with another.

The name can sound as if it favors a single “most favored” country, but the modern rule works in the opposite direction: a concession to one member is normally shared across the membership. Exceptions exist, including certain free-trade agreements and special preferences for developing countries.