There is a growing tension between congressional and executive authority over tariffs, a conflict with deep constitutional roots and real-world economic impact. With legal challenges mounting, the issue may soon reach the U.S. Supreme Court—potentially reshaping how trade policy is made in America.
What happens when a president can impose tariffs without input from Congress? And what does that mean for democracy, the economy, and the rule of law?
To unpack the legal, economic, and policy dimensions of this evolving debate, we asked Paul Stephan, director of UVA Law's Center for International and Comparative Law, and Rodney Sullivan, executive director of Darden’s Mayo Center of Asset Management, to explain the history of U.S. tariffs and what might lie ahead.
Q: What are the purpose and history of tariffs in the United States?
Paul Stephan: From the founding to the Civil War, the federal government relied on tariffs as its principal tax revenue. The antebellum North favored high tariffs to protect its textile manufacturing from lower-cost foreign competition, while the South feared retaliatory tariffs would cripple cotton exports.
After World War I, tariffs began to decline. Then, at the onset of the Great Depression, the United States imposed the 1930 Smoot-Hawley Tariff Act to protect businesses from foreign competition. In turn, most industrial countries retaliated with tariffs of their own, thus deepening the Great Depression. From 1934 until 2017, U.S. policy was based on lowering international trade barriers reciprocally, on the assumption that U.S. firms would do better in a competitive global economy.
From 1934 until 2017, U.S. policy was based on lowering international trade barriers reciprocally, on the assumption that U.S. firms would do better in a competitive global economy.
Q: Did that work?
PS: It was generally successful, but particular sectors suffered, harming principally the workers in those industries. I believe the U.S. was shortsighted in not developing ways to protect workers displaced by global competition. What resulted was a U.S. economy based increasingly on making and selling knowledge rather than things. Well-educated people thrived; people without college degrees fell behind.
The latter group is increasingly voting as a bloc and seeks to undo the economic changes of the past 40 years. Tariffs are not likely to accomplish that goal, but many in this group distrust those aligned with global free-trade policies that favor the more educated.
Q: How have recent administrations—both Republican and Democrat—approached tariffs?
Rodney Sullivan: The tariffs President Trump imposed in 2017 and then expanded in 2018 primarily targeted China, aiming to support U.S. manufacturing and reduce trade deficits. President Biden largely maintained those tariffs.
The evidence so far has been mixed: There have been some job gains with a slight rise in manufacturing employment, but no manufacturing boom. Long-term data suggests the tariffs have not yet significantly reversed the decades-long American trend of manufacturing offshoring or automation-related job loss. Many firms redirected their supply chains to other countries rather than move production back to the U.S. This reduced dependency on China but didn’t necessarily boost U.S. factory output.
Q: What are the arguments for Congress retaining primary authority over tariff policy?
PS: First, that’s what the Constitution says. Second, Congress is more broadly representative of the American people. And third, in a highly polarized political environment where standards of integrity and financial probity have slipped on both sides, leaving the authority to Congress cuts back on opportunities for side deals and corrupt payments.
In a highly polarized political environment where standards of integrity and financial probity have slipped on both sides, leaving the authority to Congress cuts back on opportunities for side deals and corrupt payments.
RS: Some in Congress have sought to narrow the scope of presidential discretion and restore congressional oversight. The Congressional Trade Authority Act, introduced in 2019 by Senators Pat Toomey (R-PA) and Mark Warner (D-VA), is aimed at preventing misuse of national security as justification for tariffs when they are actually economic or political in nature. If enacted, future tariff policy would require a more balanced process between the executive and legislative branches.
Q: How much latitude does a president have to impose tariffs without input from Congress?
PS: Several provisions in the law give presidents the power to use trade measures, including tariffs, as a response to structural imbalance of payments or national security threats. Past presidents have relied on this authority, and the courts have upheld it. What is different about the Trump administration’s 2025 tariffs is that they rely on the International Emergency Economic Powers Act of 1977 (IEPPA), which authorizes sanctions (such as those imposed on Russia after the annexation of Crimea and the invasion of Ukraine) but does not mention tariffs.
If this reaches the Supreme Court, the key question will be whether the IEEPA grants the president authority to impose tariffs beyond those approved by Congress, even under an international emergency. If not, do the new tariffs address national security or balance-of-payments concerns?
Q: What are the practical consequences if the Supreme Court rules on the issue?
RS: The ongoing tariff negotiations have already created uncertainty for businesses. If U.S. courts rule that Congress holds tariff-setting power, not the president alone, that uncertainty would give way to confusion about what comes next. Importers will likely request refunds for the duties they’ve already paid, and if Congress takes up the issue, the timeline and form of any new tariff legislation would be unclear.
If the courts grant the president greater discretion over tariff policy, there might be a marked rise in the importance and use of tariffs—and perhaps most notably as a tool to protect national security interests. Consider President Trump’s recent threat to impose tariffs on countries that purchase oil from Russia. Such strategic leverage would constitute a type of “secondary tariff,” going beyond sanctioning a specific country. This would create an expanded scope for tariffs, signaling a significant shift in how trade tools are used versus how they have been used historically in geopolitical strategy.