The U.S. Supreme Court on Thursday ruled illegal the broad tariffs U.S. President Donald Trump has implemented, saying the president does not have the authority to impose them.

According to major foreign media outlets including CNBC, the court ruled 6-3 that the president's move to levy tariffs on virtually all imports based on the 1977 International Emergency Economic Powers Act (IEEPA) infringed the taxing power granted only to Congress under the Constitution.

The ruling is a legal check on a core trade policy under which Trump has imposed high tariffs on products from major trading partners including China, Canada and Mexico, citing global trade imbalances and national security, and used them as leverage in trade negotiations.

The majority opinion stated that the IEEPA "does not give the president the authority to impose tariffs" and said the sweeping tariff measures were an abuse of executive power beyond legislative authority.

The majority opinion, which included conservative justices, stressed that taxing power should traditionally be held by Congress. However, 3 justices including Thomas and Kavanaugh issued dissenting opinions, maintaining that the Trump administration's tariff strategy was consistent with legal grounds.

The ruling could leave the government facing refund demands for tariff revenue worth tens of billions of dollars collected based on the IEEPA, and attention is also on follow-up strategies to take similar steps through other legal authority. Reports also said Trump criticised the decision at an event shortly after the ruling, calling it a "disgrace".

The case is significant in that it redefined the legal foundation of U.S. trade policy and the scope of presidential authority. It is also expected to affect future debates over how the separation of powers between the legislative and executive branches applies to trade measures.

In related news, New York stocks rose immediately after the Supreme Court issued an unfavourable ruling on Trump's tariff measures. This could provide relief for companies that have been struggling with rising costs due to tariffs, and is also expected to ease concerns about entrenched inflation that continues to trouble the U.S. economy.

The S&P 500 rose 0.7 percent, while the Nasdaq Composite gained 1.1 percent. The Dow Jones Industrial Average rose 125 points, or 0.3 percent, recouping an early-session loss of 200 points driven by disappointing economic data.

Amazon shares, which are directly affected by tariffs, jumped 2 percent after the ruling. Other companies such as Home Depot also rose. Still, there were also assessments that the overall impact on the market was relatively limited because the Supreme Court's ruling was relatively moderate.