In a 6–3 decision on Friday, the court sided with the administration in a case concerning Mr Trump’s executive order on birthright citizenship. The order seeks to end automatic citizenship for children born in the United States to undocumented migrants – a policy that has faced repeated legal challenges and temporary halts by district courts.

The White House has argued that America’s 677 federal district judges should not be able to issue rulings that apply across the entire country, a stance now upheld by the court.

Since returning to office in January, Mr Trump has issued more than 160 executive orders, including measures targeting undocumented migrants for deportation, altering the remit of the Department of Government Efficiency (Doge), and addressing the status of transgender personnel in the armed forces. Several of these directives, including the one on birthright citizenship, have been blocked by lower courts, prompting accusations from within the administration that “activist judges” are obstructing the president’s mandate.

Speaking at a White House press conference after the ruling, Mr Trump hailed the judgment as a “giant” warning and claimed American democracy had been imperilled prior to the decision.

“[These] radical left judges overruled the rightful powers of the president …” he said. “It was a great threat to democracy.”

The ruling split the bench along ideological lines, with all six conservative justices supporting the president and the three liberal members dissenting.

While the court found that lower courts had overreached, it left open the question of whether Mr Trump’s attempt to restrict birthright citizenship is itself unconstitutional. That matter is expected to be addressed during the court’s next session in October.

The decision turns on an interpretation of the 1789 Judiciary Act, which established the lower federal courts. The majority concluded that Congress did not envisage these courts issuing nationwide injunctions, but rather limiting their rulings to the specific plaintiffs before them.

Writing the majority opinion, Justice Amy Coney Barrett said: “Some say that the universal injunction ‘give[s] the judiciary a powerful tool to check the executive branch’.

“But federal courts do not exercise general oversight of the executive branch; they resolve cases and controversies consistent with the authority Congress has given them. When a court concludes that the executive branch has acted unlawfully, the answer is not for the court to exceed its power, too.”