Why the US Supreme Court's ruling blocking Trump's tariffs matters

On 20 February, the US Supreme Court issued a decision that could become a turning point for American trade policy.

In a case challenging the Trump administration, the Court ruled that the president cannot impose sweeping import tariffs under emergency powers unless Congress has explicitly granted that authority by statute.

As a result, sweeping tariffs ranging from 10% to 50%, introduced by Donald Trump in early April 2025 on imports from most countries, are expected to lose legal force. However, the US president has found an alternative mechanism and announced temporary tariffs for 150 days – initially at 10%, later raising them to 15%.

Thus, uncertainty surrounding the future of global trade remains.

Read more on the Court’s ruling and its possible consequences in the article by Olena Omelchenko of the law firm Ilyashev&Partners: A new tariff revolution: how Trump’s court defeat reignited the US trade war with the world.

The Supreme Court’s ruling concerns far more than individual tariffs. It establishes an important legal boundary that strengthens the predictability of US trade policy.

The Trump administration justified launching a trade war against most trading partners by invoking the International Emergency Economic Powers Act (IEEPA), a 1977 law that allows the president to respond to extraordinary economic threats.

This allowed the administration to bypass congressional approval for new tariffs, where such an initiative might not have secured sufficient support. The president declared that the US trade deficit constituted an "extraordinary and unusual threat" posed to the US economy ans security.

However, the Court effectively reaffirmed a fundamental principle of the US constitutional framework: the power to levy taxes, duties and other charges belongs to the US Congress, not the president.

At the same time, practical implications of the ruling remain uncertain. Could it affect the fate of tariffs already paid by importers under measures deemed to exceed presidential authority? What will happen to supplementary trade agreements concluded with the United States (including with the EU) aimed at reducing the new American tariffs?

Ultimately, President Trump quickly found an alternative legal mechanism for imposing new tariffs.

He relied on the Trade Act of 1974, which allows the president, without congressional approval, to impose tariffs of up to 15% for up to 150 days.

For the European Union, the Supreme Court’s decision offers hope for reducing the risk of sudden tariff measures from the White House and for greater predictability in transatlantic trade.

The ruling also has practical implications for Ukraine.

Ukrainian exports to the United States, primarily metallurgical products, semi-finished goods, as well as certain agricultural and industrial products, are sensitive to changes in the trade regime. For a country building economic integration on a rules-based foundation, predictability in the policies of key partners is critically important.

The Supreme Court’s decision matters not because it immediately changes US trade policy.

It matters primarily because it sets a boundary: the president cannot assume powers that the US Constitution assigns to Congress.

Even in periods of political pressure and economic competition, trade instruments remain a matter of law, not political improvisation.

And this boundary, between delegated authority and its overreach, is crucial for the stability of both the national and international trading systems.