Trade Enhancement Act of 2003

Trade Enhancement Act of 2003 - Amends the Trade Act of 1974 to make an act, policy, or practice unjustifiable if it constitutes fostering by a foreign government of systematic anticompetitive activities by persons or among persons in one or more foreign countries that have the effect of restricting, on a basis inconsistent with commercial considerations, access of U.S. goods or services to a foreign market or diverting foreign goods or services toward the U.S. market. Makes it an unreasonable act, policy, and practice for a foreign government to tolerate such systematic anticompetitive activities.

Requires the United States Trade Representative (USTR), in addition to determining what action to take with respect to any act, policy, or practice found unjustifiable or unreasonable, to: (1) further determine whether there is reason to believe that the conduct of the foreign country concerned involves anticompetitive conduct engaged in by any natural or corporate person or persons; and (2) if so, refer the matter to the Attorney General for investigation into whether such conduct violates the Sherman Act.

Amends the Sherman Act to require the Attorney General to: (1) conduct such an investigation if the USTR refers such a matter; and (2) commence an action in a U.S. district court seeking injunctive and other relief if an investigation results in an affirmative determination.

Amends the Trade Act of 1974 to authorize the USTR to use, if it has a reasonable basis, an inference adverse to the interests of any foreign government which has failed to cooperate by not acting to the best of its ability to: (1) comply with a reasonable request for information; or (2) require a party within its jurisdiction to comply with a reasonable request for information.