• U.S. Trade Representative Jamieson Greer expressed confidence in a favorable Supreme Court ruling on tariffs, but acknowledged the case is not guaranteed for plaintiffs.
  • If the Court rules against the government, the administration plans to implement replacement tariffs "the very next day" using alternative legal mechanisms.
  • The decision, expected imminently after missed announcement dates, could reshape presidential tariff authority and impact ongoing trade deals.

In a CNBC interview, U.S. Trade Representative Jamieson Greer struck a measured tone about the Supreme Court case challenging the Trump administration's tariffs, describing it as far from a sure win for plaintiffs while outlining contingency plans to maintain the policy's continuity. "We're confident in our legal position, but this isn't open and shut," Greer said, according to people familiar with the interview. "We have tools ready to go if needed."

The Supreme Court has passed earlier announcement dates of January 9 and 14 without rulings, leaving market watchers on edge for a decision that could come any day now. Lower courts ruled against the tariffs in May and August 2025, citing Congress's exclusive authority over tariffs and prompting the administration's appeal. During oral arguments on November 5, 2025, justices questioned the legality of using the 1977 International Emergency Economic Powers Act (IEEPA) for tariffs—a novel application now under scrutiny.

Greer emphasized in multiple interviews, including with The New York Times and The Economist, that the administration would not let a loss derail its trade agenda. "We'd have replacement tariffs in place the very next day," he told CNBC, pointing to other legal mechanisms to preserve negotiated deals and support President Trump's policies. This rapid-response approach aims to avoid disruptions to what officials call "trade peace," though business groups worry renewed tariff threats could strain alliances and supply chains.

Behind the scenes, efforts to maintain the tariff framework have intensified. Treasury Secretary Scott Bessent called a reversal "very unlikely," while Greer briefed Congress on the USMCA without withdrawal plans. The administration's confidence stems partly from the Court's 6-3 conservative majority, despite legal experts predicting possible limits on IEEPA use. "What we're focused on is regulatory stability and reciprocity," Greer said, echoing themes from recent tours in Ohio and Michigan defending "auto affordability" amid tariff implementation.

Tariffs imposed starting April 2025—on autos, parts, and doubled steel/aluminum—have already spurred deals opening markets in the UK, EU, Japan, and others, attracting U.S. investments and benefiting farmers, according to administration officials. But critics like the National Foreign Trade Council warn of higher consumer prices, while Sen. Ron Wyden dismissed tariff threats on Greenland as "deranged." Greer pushed back, claiming in CNBC remarks that policies are reducing vehicle prices amid rising wages, though fact-checks note stable new car prices and declining used ones.

Looking ahead, the ruling could reshape presidential power over trade, with implications for the USMCA review in 2026 and ongoing talks on digital taxes and security. "Without a deal, we'd risk losing hard-won gains," a person familiar with the matter said, highlighting the stakes. For now, the administration waits, ready to pivot if the Court delivers an unfavorable verdict—a move that would test its ability to sustain what Greer calls a "steady growth trajectory" in trade enforcement.