Whitney v. Robertson

Whitney (plaintiff), a sugar importer from the Dominican Republic, argued he should not owe duties because a treaty guaranteed the Dominican Republic duty treatment no less favorable than any other country, and Hawaiian sugar entered duty-free. But a later-enacted federal statute authorized collecting duties on Dominican Republic imports. Whitney sued customs official Robertson (defendant); the lower court ruled for Robertson, and Whitney appealed.

Whether a federal statute enacted after a self-executing treaty, and inconsistent with it on the same subject matter, prevails as the supreme law of the land.