A Trump Tariff Gets Nailed in Court

President Trump’s metal tariffs took a loss in federal court Monday, and the details bolster the argument for Congress to reclaim its rightful trade power. Mr. Trump acted under a legal provision called Section 232, which lets the President move against an import if he deems it a threat to national security. That term is elastic.

The Trump Administration considered taxing foreign automobiles, as if imported Voltswagens—sorry, Volkswagens—were a real threat. The power that Section 232 delegates is so unbounded that, in a 2018 argument, the government’s lawyer declined to answer directly when asked whether the President could unilaterally put a tariff on peanut butter.

The only constraint seems to be a timeline: After he gets the official findings on the supposed threat, the President must act within 105 days. In January 2018, Commerce Secretary Wilbur Ross delivered a report on steel imports, which was followed by Mr. Trump’s initial metal tariffs. Two years later, in January 2020, Mr. Trump added new 25% taxes on steel nails and other items, as well as 10% on some aluminum articles.

Given the lag, the U.S. Court of International Trade, in 2-1 ruling on Monday, declared Mr. Trump’s 2020 tariff proclamation “invalid as contrary to law.” It’s a modest but good win for free trade, especially now that President Biden isn’t looking eager to end Mr. Trump’s trade wars.

Congress should regret the way it has unjealously ceded its trade authority to the executive. The power to tax at the border, as anywhere else, is the power to destroy. That’s no doubt how it felt to the American business owners who had their supply chains upended by Mr. Trump’s tariffs, and who then had to beg Washington for a tariff exclusion.