Little v. Barreme
United States Supreme Court
6 U.S. 170 (1804)
During wartime with France, Congress authorized the President to direct armed-ship commanders to stop, examine, and seize any American vessel reasonably believed to be violating the trade suspension, but only if it appeared to be sailing to France. Because that narrow language could be easily evaded, the President's executive order went further, authorizing commanders to also stop and seize vessels sailing from French ports, including ships that might secretly be American despite carrying Danish or other foreign papers - a broader power Congress's own statute never granted. Acting under that executive order, Captain Little (defendant) seized the Flying-Fish, a Danish vessel he suspected was really American, as it returned from a French port; the ship's owners (plaintiffs) sued Little for trespass.
Whether the President of the United States may issue an executive order that supersedes or contradicts a congressional act, even in times of war.