The White House is set to impose a 15 percent tariff through Section 122 of the Trade Act of 1974 after the US Supreme Court ruled against Donald Trump’s use of the International Emergency Economic Powers Act of 1977.

United States President Donald Trump has ramped up tariff threats following last week’s US Supreme Court decision that ruled that Trump’s sweeping global tariffs, imposed under the International Emergency Economic Powers Act, were unlawful.

On Monday, Trump said that any countries that wanted to “play games” after the high court’s ruling would be hit “with a much higher tariff ” in a post on his social media platform Truth Social.

In a separate post on the platform, Trump claimed that he does not need the approval of the US Congress for tariffs.

“As President, I do not have to go back to Congress to get approval of Tariffs . It has already been gotten, in many forms, a long time ago! They were also just reaffirmed by the ridiculous and poorly crafted supreme court decision!” Trump said in the post.

Trump does have some authority to impose other tariffs, but they are much more limited.

Following the court’s 6–3 decision on Friday, the president said he would introduce a 10 percent tariff, raising it to 15 percent by Saturday under Section 122 of the 1974 Trade Act, the maximum limit under the statute that enables the White House to impose tariffs for 150 days.

The statute only requires a presidential declaration and does not require further investigation. Section 122 is only temporary; the tariffs would then expire unless Congress extends them.

Trump’s tariffs are overwhelmingly unpopular. A new Washington Post-ABC News-Ipsos poll found that 64 percent of Americans disapprove of the president’s handling of tariffs.

Looming uncertainty

Experts warn that Trump’s newly imposed tariffs will fuel further economic uncertainty.

“What we do know is that it would continue to require all those parties affected to continue to live in uncertainty and, as many have already pointed out, such uncertainty is not good for our economy and has negative impacts on American consumers,” Max Kulyk, partner and CEO of Chicory Wealth, a private wealth advisory firm, told Al Jazeera.

“It’s impossible to plan. You hear that tariffs are off, and you are considering how to get refunds. Then a few hours later, it’s 10 percent. Then it’s 15 percent the next day…. Not having that stable framework is hurtful for activity, hiring, investment,” Gregory Daco, chief economist at EY-Parthenon, told the Reuters news agency.

Gold, which is considered a safe investment in times of economic uncertainty, surged by 2 percent on Monday, hitting a three-week high as tariff pressures remain unclear.

US markets are also taking a hit. The tech-heavy Nasdaq is down 1.1 percent in midday trading. The S&P 500 is also down by 1 percent, and the Dow Jones Industrial Average slumped by 1.5 percent since the market opened on Monday.

Stalling trade deals

Trump’s erratic approach has also deterred movement on looming trade deals.

On Monday, the European Parliament opted to postpone voting on a trade deal with the US. It is the second time the bloc has pushed back the vote. The first was in protest against Trump’s unsolicited attempts to acquire Greenland.

The assembly had been considering removing several European Union import duties on US goods. Committee chair Bernd Lange said the new temporary US tariff could mean increased levies for some EU exports, and no one knew what would happen after they expire in 150 days. EU lawmakers will reconvene on March 4 to assess if the US has clarified the situation and confirmed its commitment to last year’s deal.