BOUDIN, Circuit Judge. Trailer Marine Transport Corp. ("Trailer Marine"), the plaintiff-appellee, brought suit in the district court to challenge the constitutionality of a motor vehicle fee as it applies to trailers used in transporting goods to and from Puerto Rico. The district court held that the Commerce Clause of the Constitution, art. I, § 8, cl. 3, does apply to legislation and administrative measures enacted or adopted by Puerto Rico. The district court further held that the fee as applied to such trailers violates the Commerce Clause. The agency and officials defending the fee, who are defendant-appellants in this case, appeal. We affirm.
