US Supreme Court justices raised doubts on Wednesday over the legality of President Donald Trump’s sweeping tariffs in a case with implications for the global economy that marks a major test of Trump’s powers.

Conservative and liberal justices alike sharply questioned the lawyer representing Trump’s administration about whether a 1977 law meant for use during national emergencies gave Trump the power he claimed to impose tariffs or whether the Republican president had intruded on the powers of Congress.

But some of the conservative justices also stressed the inherent authority of presidents in dealing with foreign countries, suggesting the court could be sharply divided in the outcome of the case.

The court has a 6-3 conservative majority. The arguments, lasting more than 2-1/2 hours, came in appeals by the administration after lower courts ruled that Trump’s unprecedented use of the law at issue to impose the tariffs exceeded his authority.

Businesses affected by the tariffs and 12 US states, most of them Democratic-led, challenged the tariffs.