The US Supreme Court began its 2026-27 term on Tuesday with a central challenge to President Donald Trump's emergency tariff powers. The justices returned to Washington as the federal government shutdown stretched into its sixth day.

The court is weighing whether Trump exceeded his authority under the International Emergency Economic Powers Act by imposing sweeping global tariffs without congressional approval. Lower courts, including the US Court of Appeals for the Federal Circuit, previously ruled key measures unlawful, prompting the administration's appeal to the high court.

Chief Justice John Roberts and the eight associate justices face a crowded calendar that also includes disputes over birthright citizenship and executive removal powers. The tariff case represents the most consequential separation-of-powers test of Trump's second term, affecting hundreds of billions of dollars in trade revenue.

The shutdown, now the longest since 2018-19, has sharpened scrutiny of executive authority as the White House and Senate remain deadlocked on spending. Democratic senators led by Chuck Schumer have argued the tariff dispute underscores a broader pattern of the administration bypassing Congress.

A ruling in the tariff case is not expected immediately, but the court's handling of oral argument scheduling will signal how quickly the justices intend to resolve the question.