Over its first two years, the Trump administration has aggressively reshaped U.S. trade policy. One of its most controversial initiatives is the expansive use of national security to justify imposing tariffs and quotas. Section 232 of the Trade Expansion Act of 1962 gives the president authority to restrict imports on this basis after an investigation by the Department of Commerce. The administration has already done so for steel and aluminum and is now threatening similar actions on automobiles. The World Trade Organization (WTO) has a special exception for such measures, so there is at least an argument that they are permitted under international law. The CATO Institute’s Simon Lester and Huan Zhu, in a new Policy Analysis paper, write that the administration, however, has taken what was previously considered a narrow and exceptional remedy and broadened it to serve as a more general tool to protect domestic industries.