When President Trump announced his sweeping new tariffs this year, many trade law experts were startled. Typically, presidents don't have the authority to impose broad tariffs with a snap of their fingers.But Trump's advisors have an unusual new legal theory. They say that as long as there's a national emergency of some kind, Trump may be able to create whatever tariffs he wants. This is a creative interpretation of a 1977 law called the International Emergency Economic Powers Act, or IEEPA. To justify his latest tariffs, the president declared national emergencies involving illegal immigration, the fentanyl crisis, and the trade deficit.But no president has ever tried to use the law in this way. Now, the fate of Trump's tariffs — and the creative legal theory behind them — lies with the courts. About a dozen lawsuits have challenged his tariffs, claiming that they are unlawful and possibly even unconstitutional. And some judges have started to agree.On today's show: What are the President's powers when it comes to tariffs? Where do they come from? What are their limits? And, what will be the fate of Trump's tariffs?For more on Trump's tariffs: - The 145% tariff already did its damage - Do trade deficits matter? - What "Made in China" actually meansFind more Planet Money: Facebook / Instagram / TikTok / Our weekly Newsletter.Help support Planet Money and hear our bonus episodes by subscribing to Planet Money+ in Apple Podcasts or at plus.npr.org/planetmoney.Learn more about sponsor message choices: podcastchoices.com/adchoicesNPR Privacy Policy