National treatment

National treatment is a principle in customary international law vital to many treaty regimes. Under national treatment, if a state grants a particular right, benefit or privilege to its own citizens, it must also grant those advantages to the citizens of other states while they are in that country. In the context of international agreements, a state must provide equal treatment to those citizens of other states that are participating in the agreement.
See more at Wikipedia.org...

A tenet of international trade agreements whereby nations must afford imported goods the same treatment that they afford domestic or national products (no discrimination). - (read more on National treatment)