Friday’s Supreme Court decision rebuffing President Trump’s signature foreign policy initiative—worldwide tariffs imposed pursuant to an asserted national emergency—was extraordinary in multiple respects. In its nearly 250-year history, the Court has rarely ruled against presidential assertions of emergency power. It authorized, for example, the imprisonment of war critics during World War I, and the internment of Japanese Americans and the execution of foreign “saboteurs” without a jury trial during World War II. Yet here the Court directly rejected the president’s claim of emergency authority. What’s more, a Supreme Court decision has seldom if ever had such severe economic consequences for the federal fisc. The tariffs it declared unlawful have generated more than $100 billion in revenue, much of which may now need to be refunded. (The Court left the details of how and to what extent the tariffs will be refunded to the lower courts, where there is certain to be substantial further litigation.)  The decision’s political alignment was also unusual. The Court often divides 6-3, as it did Friday—but rarely with the three Democratic …