Contrary to the opinions of those who hurl TACO insults at him, the president is aiming to patch up the holes the Supreme Court blew in his industry-wide and country-specific tariffs, which his administration implemented under the International Emergency Economic Powers Act of 1977 (IEEPA). And one of the laws he’s using to push his agenda has already proven effective for him in the past. In fact, even President Joe Biden used it.

United States Trade Representative (USTR) Jamieson Greer announced Wednesday the Trump Administration is initiating probes targeting China, the EU, Mexico, and more than a dozen other countries, associated with “structural excess capacity,” or the overproduction of goods that exceed global demand, as part of Section 301 of The Trade Act of 1974. Section 301 is one of the tools the president has turned to after the Supreme Court struck down his sweeping tariffs implemented under IEEPA. The law arms the president with the power to impose country-specific tariffs on countries; the U.S. deems to have engaged in unfair labor practices.

There have been more than 130 cases associated with the law, establishing a formidable precedent for its use. After Trump implemented tariffs under the law against China during his first term, Biden in 2024—during the four-year periodic review practice as required under the law—extended the tariffs on China, and even increased them on products like electric vehicles and medical materials.

And the law may very well hold up in a potential legal battle: it certainly has stronger legal legs than the tariffs implemented under IEEPA, a law that had never before been used for tariffs. Tariffs imposed under Section 301 have survived many legal challenges. In 2023, approximately 3,600 importers contested the 25% tariffs on hundreds of billions of dollars’ worth of Chinese-origin goods at the Court of International Trade.

“For the plaintiffs, challenging whatever the administration does here is going to be much more difficult than the IEEPA case,” Timothy Meyer, an international trade expert and Duke Law School professor, told Fortune.

The regulatory snafus of section 301

But the caveat to Section 301 is its mandatory regulatory period, which is more rigorous than the nearly immediate authority found in IEEPA. Because Section 301 is an agency action, the acting USTR must follow guidelines under the Administrative Procedure Act, a law that governs the internal procedures of federal agencies, including providing a public comment period that allows importers and other stakeholders to influence and potentially modify the list of targeted products and tariff rates.

These investigations can legally take up to a year. But the administration seems determined to fast track the process, potentially rolling out tariffs in time for when the current short-term 10% tariffs enforced under Section 122 of the 1974 Trade Act are set to expire by the end of July.

Still, Meyer said if the administration successfully adheres to the procedural mandate associated with Section 301, it could lead to a legally-sound case for new tariffs. “I think the administration, if it does the investigation well, is going to have a reasonably good litigating position here,” he said. “But a lot depends on what the administration does.”

What can importers expect?

The potential tariffs associated with Section 301 throw another layer of uncertainty atop an already volatile trade landscape. “[Importers] are asking a lot of questions,” Blake Harden, who helps run EY’s global trade policy practice as a managing director in Washington, D.C., told Fortune. “They’re trying to understand how quickly this could potentially go. They’re trying to understand if this is something that they should comment on.”

There’s also concern that some sectors already under investigation as associated with Section 232, another legal arm the president has sought to enforce tariffs, could be subject to a “double-scope” with the addition of a second investigation associated with Section 301. And to add even more uncertainty, Harden said these investigations could cause some countries currently negotiating trade deals with the U.S. to proactively add provisions that would shield them from investigation. Alternatively, she said it could derail current trade talks. 

“[Importers] are asking, ‘What does this mean for the trade deal with country X?’ How is that going to potentially accelerate the discussions and negotiations or potentially cause those to perhaps go off the rails or to be paused?’”