WASHINGTON – The fate of the majority of President Donald Trump’s tariffs is in the hands of the US Supreme Court after lower courts ruled that they were issued illegally under an emergency law. The tariffs have remained in place to

allow the Trump administration to appeal to the highest court

Lower courts have struck down tariffs that Mr Trump imposed by invoking the International Emergency Economic Powers Act (IEEPA). These include a minimum baseline tariff of 10 per cent on imports, with some exceptions; so-called reciprocal tariffs ranging from 10 per cent to 41 per cent on goods from countries that failed to reach trade deals with the US; and extra levies on some imports from Mexico, China and Canada that Trump said were justified by the fentanyl crisis in the US.

The Supreme Court case does not touch upon the duties imposed on certain product categories using different legal foundations. For example, the Trump administration has put in place levies on steel, aluminium, cars, copper products and lumber by harnessing Section 232 of the 1962 Trade Expansion Act. Those tariffs depend on Commerce Department investigations that concluded that imports of such products pose a national security risk. 

Article 1 of the US Constitution gives Congress the power to levy taxes and duties, and to “regulate commerce with Foreign Nations”. But lawmakers have for decades delegated parts of their power over trade via various bits of legislation, most of which allow presidents to deploy tariffs only for limited reasons.

While Mr Trump tested the boundaries of those powers in his first term, this time around he invoked what he claimed were virtually unlimited powers under IEEPA to impose tariffs via executive orders. The 1977 law had never been used for this purpose before and does not mention tariffs.

IEEPA grants the president authority over a variety of financial t...