Facing a nationwide steel strike during the Korean War, President Truman ordered his Secretary of Commerce to seize the mills to keep them running. The Court struck the seizure down. Justice Black's majority opinion held that the President's power must stem either from a statute or the Constitution itself, and neither authorized this taking. But it is Justice Jackson's concurrence that became the enduring framework for presidential power. Jackson sorted executive action into three zones: (1) acting with congressional authorization, where presidential power is at its maximum; (2) acting in the 'zone of twilight' where Congress is silent; and (3) acting against Congress's expressed or implied will, where presidential power is 'at its lowest ebb.' Truman was in zone three and lost. Jackson's tripartite framework governs modern separation-of-powers analysis, from Iran-Contra to the war on terror to travel-ban litigation.