Too much of that authority has been ceded. The past 18 months show that Congress needs to reinsert itself into the trade policymaking process again.

The balance of authority favoring the executive branch largely produced positive results for the last 80 years. Every president since Herbert Hoover, Republican and Democrat, supported a general policy of trade liberalization to promote economic growth and as a vital strategic tool to make the world safer. This broad consensus is one of the great bipartisan policy achievements of the post-World War II era, and it largely succeeded in achieving these twin aims.

U.S.-led commercial diplomacy produced valuable trade agreements and institutions like the General Agreement on Tariffs and Trade (GATT) and its successor, the World Trade Organization (WTO), that have served both U.S. and global interests. By strongly disfavoring unilateral protectionism, the rules-based system sought to minimize beggar-thy-neighbor contagion from spreading the way it did in the early 1930s and to make trade more predictable by establishing an orderly process to resolve disputes.

The Trump administration has firmly rejected this order, preferring an aggressive brand of unilateralism and ad hoc policymaking of the sort the system is designed to minimize. The most egregious example of the administration’s antipathy toward the rules and norms that govern trade policy is its use of so-called national security tariffs under Section 232 of the Trade Expansion Act of 1962. That provision gives the president wide latitude to impose import restrictions if the U.S. Commerce Department determines that importation of certain products jeopardizes U.S. national security. Historically, this authority has been invoked sparingly and judiciously, given the gravity of the claim.

To date, the Trump administration has used Section 232 to impose stiff tariffs on steel and aluminum, and it is threatening to use the statute to levy duties on imported automobiles and automotive parts. Unsurprisingly, this has triggered widespread retaliation against U.S. exports, ensnaring unrelated industries into trade conflicts, and it is fostering distrust among longtime allies.

The national security rationale for the tariffs is exceedingly thin, and President Donald Trump’s own words have undercut the legal justifications articulated by his administration. In one instance, the president tweeted that the tariffs on Canadian steel and aluminum were a response to the country’s protectionist dairy policies. He has threatened Mexico with national security tariffs on automobiles if the country did not adequately address his concerns about immigration and drugs flowing into the United States and continues to threaten the European Union with tariffs on cars unless it bends to his will in prospective trade negotiations. These flagrant abuses of the statute are meant more to pry open foreign markets for U.S. exports than to actually protect national security.