Tariffs Are Here to Stay

Expectations are high that the U.S. Supreme Court will rule against the Trump administration’s use of the International Emergency Economic Powers Act (IEEPA) – the 1970s legislation that allows a president to declare a national economic emergency – to justify tariffs. Betting markets had placed the odds of a ruling in favor of the president’s use of IEEPA at about 40% before the recent oral arguments on November 5, but since then, the odds have dropped to roughly 20%, according to outcome trading platform Kalshi.

Even if the Court deems the IEEPA tariffs invalid, we doubt it will matter much in the long run, other than creating near-term uncertainty around tariff details and briefly refocusing markets on deficits. Keep in mind that although the Court may find IEEPA does not allow tariffs, Congress has granted the president explicit tariff powers for reasons ranging from balance-of-payments to national security. Unlike IEEPA, these powers are more limited and require extensive, time-consuming investigations and/or congressional oversight. The point stands: Even if IEEPA is overruled, the president still has broad authority to advance a trade agenda. Indeed, as the IEEPA case has proceeded through the U.S. court system, the administration has begun laying the groundwork to rebuild current tariff policies through more legally durable means.

As such, the current 13% average effective tariff rate (according to Treasury collections data) is likely here to stay. Businesses that have been slow to adjust, given heightened policy uncertainty, will have to adapt. At the same time, the potential for the Court ruling to trigger refunds of IEEPA-related tariffs paid in 2025 could give businesses some additional near-term flexibility, although knotty details may slow those refunds.

Expediency vs. legal legitimacy

Tariffs and trade policy were central to President Trump’s campaign, and he moved quickly once in office. He implemented sweeping tariffs, preferring to enact them under IEEPA – a legally untested use of presidential emergency powers. IEEPA does not explicitly mention tariffs, and its use may be overturned, but it allowed time to build stronger legal cases through Commerce Department investigations.

U.S. trade law grants the president broad (but not unlimited) power to impose tariffs. For example, Section 232 of the 1962 Trade Expansion Act allows the president to impose tariffs or quotas on products if the Commerce Department finds that imports impair national security. These powers have been used under Trump 2.0 for sweeping tariffs on steel, aluminum, autos, and parts. Section 301 of the 1974 Trade Act allows the president to impose tariffs or other restrictions in response to unfair trade practices by another country. The first Trump administration did this in the case of China after finding unfair practices, including intellectual property theft, forced technology transfers, and discrimination. Both Sections 232 and 301 require detailed investigations by the Commerce Department.

More general economic or balance-of-payments threats fall under Section 122 of the Trade Act, allowing for a sweeping 15% tariff on imports to address large trade deficits, which the U.S. has run for decades. However, without congressional approval, the president is limited to a 150-day implementation window.

Quantifying IEEPA tariffs

President Trump used IEEPA to impose more than half of this year’s tariffs, including measures on Mexico, Canada, Chinese fentanyl-related tariffs, and reciprocal tariffs on various other countries. Lower courts have ruled that this is unlawful, though they allowed the tariffs to remain in place while litigation continues.

During oral arguments two weeks ago, Supreme Court justices appeared unsurprisingly uncomfortable with the use of IEEPA to impose tariffs specifically – not the president’s emergency declaration more generally (as argued by the lower courts) – laying the groundwork for a likely ruling against the president.

IEEPA tariffs currently add roughly 8 percentage points (ppts) to the approximately 13.5% effective U.S. tariff rate. A broad ruling against the administration’s IEEPA usage could therefore reduce the effective rate by that amount, though a narrower ruling is possible.