With a congressional vote looming in the spring of 2000, President Bill Clinton mustered his best arguments for why lawmakers should approve his proposed deal for China to join the World Trade Organization.

Adding China would link Beijing to Western economies and reduce the government’s ability to control its vast population, he said in a speech that March at Johns Hopkins’s School of Advanced International Studies. “By joining the WTO, China is not simply agreeing to import more of our products, it is agreeing to import one of democracy’s most cherished values, economic freedom,” Mr. Clinton said. “When individuals have the power not just to dream, but to realize their dreams, they will demand a greater say.”

Mr. Clinton’s idealistic rhetoric played well among most of Washington’s elites, but a trade lawyer often dismissed as a protectionist, Robert Lighthizer, was skeptical. As he had warned in a New York Times op-ed a few years earlier, if admitted to the WTO, mercantilist China would become a “dominant” trading nation. “Virtually no manufacturing job in [the U.S.] will be safe,” he wrote.

Mr. Lighthizer is now the U.S. Trade Representative, President Donald Trump’s chief negotiator on global trade. In the administration’s view, allowing China to enter the WTO in 2001 was a historic mistake that cost the U.S. millions of jobs and trillions of dollars in accumulated trade deficits. The U.S. is now bypassing WTO rules and threatening Beijing with tariffs on up to $500 billion of imported goods.

The moves against China are part of Mr. Trump’s wider effort to upend longstanding U.S. policy on trade and also the international institutions and agreements that govern trade. Whether the administration’s shift is a much-needed corrective or a disastrous reversal depends in large part on how one views the original decision to bring China into the international trade regime.