President Donald Trump has moved swiftly to impose a new 10% tariff on imports from most countries, just hours after the Supreme Court struck down his broader tariff regime as exceeding presidential authority.

The Supreme Court’s 6-3 decision ruled that Trump’s sweeping tariffs on goods from over 100 countries were imposed without proper congressional authorization, marking a significant constitutional check on executive power over trade policy.

However, Trump immediately invoked a narrower trade authority to implement the 10% rate, describing the court ruling as “a minor speed bump” in his economic agenda.

“The tariffs are back,” Trump said in a statement from the White House. “We will protect American workers and American industry, regardless of what activist judges say.”

Markets reacted with volatility, with the Dow Jones falling 300 points before recovering as traders assessed the implications of the new, somewhat lower tariff structure. Trade lawyers said the new tariffs are likely to face their own legal challenges.