When he ran for president, he had been involved in some 4,000 lawsuits, a USA Today tally found, about 40 percent filed by Trump and his businesses. He brought the practice with him into politics, threatening to sue, or actually suing: Sen. Ted Cruz (“for not being a natural born citizen”), Gov. John Kasich of Ohio, the New York Times, the Washington Post, Univision, the publisher of Fire and Fury, the Club for Growth, the Culinary Workers Union,...