America’s Founders made the presidential pardon power absolute, and they did so as a protection against injustice. But Hamilton and Madison might be having second thoughts as they watch President Trump dole out pardons as a form of political legal tender. In the latest example, Mr. Trump on Wednesday pardoned crypto kingpin Changpeng Zhao, who happens to be a Trump family business partner. “I gave him a pardon at the request of a lot of very good people,” Mr. Trump said. “A lot of people say that he wasn’t guilty of anything.” One of those people wasn’t Mr. Zhao, unless...