A coalition of 12 U.S. states are suing to halt the Trump administration's tariffs, while arguing that only Congress should have the power to enact the levies.

BBC News reports that the lawsuit is being led by New York's governor and attorney general, and includes Illinois, Oregon, Colorado and Arizona among others. In their filing with the U.S. Court of International Trade, the states assert that the White House's strategy to announce and enact tariffs through social media posts and executive orders amounts to "a national trade policy that now hinges on the President's whims rather than the sound exercise of his lawsuit authority." 

"By claiming the authority to impose immense and ever-changing tariffs on whatever goods entering the United States he chooses, the President has upended constitutional order and brought chaos to the American economy," the lawsuit reads. 

Trump has claimed that 1977's International Emergency Economic Powers Act (IEEPA) gives him the ability to unilaterally implement tariffs as he sees fit, due to wording in the law that allows the President to regulate international trade in response to a national emergency. The White House declared such an emergency in early April, over U.S. trade deficits that have supposedly "led to the hollowing out of our manufacturing base."

The lawsuit brought by states contends that the IEEPA doesn't justify the broad powers Trump claims to have, pointing to the original intent of the law, which was actually related to limiting the executive's authority. According to research from Congress, the law has also never previously been used as a justification for tariffs.

"IEEPA was enacted to restrain the President's powers, not enlarge them," the states claim, detailing how the law was devised as a response to past administrations using emergency powers granted by 1917's Trading with the Enemies Act "as shortcuts around peacetime constraints." 

The lawsuit goes on to warn of the larger economic dangers posed by Trump's tariffs, with U.S. business growth hitting its lowest levels since late-2023, according to S&P Global Market Intelligence. In an April 24 briefing, S&P cited "growing concerns" over the uncertainty created by the Trump administration's trade policies.