WASHINGTON — President Donald Trump is set to introduce a new legal framework for his tariff program this week while accelerating trade negotiations with North American partners, signaling a renewed period of uncertainty for global businesses after several months of relative stability.

Following the U.S. Supreme Court’s February ruling that invalidated much of Trump’s second-term tariff regime, the administration implemented a temporary 10% tariff on nearly all imports, effective for 150 days. This interim measure, which expires early Friday, brought a measure of calm after a year marked by frequent and unpredictable trade policy shifts.

U.S. Trade Representative Jamieson Greer indicated on Tuesday that replacement tariffs will be announced soon, and on Monday, President Trump announced plans to impose additional 50% tariffs on select Canadian goods. This latest move is designed to increase pressure on Canada in ongoing efforts to renegotiate provisions of the U.S.-Mexico-Canada Agreement (USMCA). The tariffs targeting Canada are separate from the broader global levies the administration aims to establish following the Supreme Court’s decision.

“We’re just days away from a significant shift,” said Drew DeLong, a former State Department official now at consulting firm Kearney. He added that many companies, having experienced a relatively quiet period in tariff policy, may be caught off guard by upcoming changes.

In response to the court’s ruling that Trump had exceeded his authority under a 1970s emergency statute, the administration plans to rely on Section 301 of the Trade Act of 1974 for the new tariffs. This legal basis is expected to offer a more robust defense against potential challenges. While the administration has indicated it aims to maintain tariff levels comparable to those expiring this week, adjustments remain possible.

Since March, the USTR has been conducting a tariff investigation under Section 301 into countries alleged to allow forced labor in their supply chains. A preliminary determination released earlier this month proposed tariffs of 10% on goods from more than a dozen U.S. trading partners, including Canada, Mexico, and the European Union, and 12.5% on products from over 40 nations such as China, India, Japan, and South Korea. Collectively, these tariffs could affect 99% of U.S. imports.

The final report for this investigation, which will address over 1,500 public comments including exemption requests from U.S. companies, is due imminently. Ryan Majerus, a former Commerce Department trade official, described the timeline as “incredibly tight” for finalizing the report and providing guidance for enforcement.

Though tariff levels may shift, Majerus does not anticipate increases beyond the caps established in agreements negotiated last year with the European Union, Japan, and South Korea, which generally limit tariffs to 15%. Separately, the USTR has initiated another Section 301 investigation focused on industrial overproduction by China and multiple other countries, with a preliminary tariff proposal expected possibly next month.

If implemented, the combined Section 301 tariffs could return average U.S. tariff rates to roughly 17%, up from about 11% under the current temporary tariffs, DeLong said.

On the USMCA front, U.S. officials are engaged in a third round of talks with Mexico in Mexico City this week, while formal negotiations with Canada have yet to commence. The imposition of the new Canada tariffs this week has strained relations, even as the United States remains a significant market for Canadian exports. Canada could see growth reduced by approximately 1.5 percentage points this year compared to pre-tariff forecasts, according to its central bank.

The $20 billion affected by the tariffs represents a small fraction of Canada’s $380 billion in exports to the U.S., but the legal basis for the tariffs has drawn attention. Trump invoked Section 338 of the Tariff Act of 1930, a rarely used provision addressing alleged discrimination against U.S. goods, which may allow for more immediate tariff impositions without the extended investigatory process required under Section 301.

Industry reactions remain mixed. Jake Colvin, president of the National Foreign Trade Council, expressed support for the broader objective of encouraging domestic production but cautioned that “frequently changing the rules and ramping up new tariffs every few weeks isn’t the way to do it.”