President Trump threatened on Thursday to leave the World Trade Organization. As far-fetched as that might seem, his language on this threat was not ambiguous: “If they don’t shape up, I would withdraw from the WTO.”

Trump’s criticisms of the WTO were partly justified, based on Chinese abuses of intellectual property law that have been essentially given a pass. But he also views the WTO as a bad deal because it restricts his own power to control American trade policy. Here, he is very wrong. For the United States and other member countries, WTO limits are often the only thing standing between them and their own worst impulses.