Eight justices—the exception being Ketanji Brown Jackson—seem keen to rein in universal injunctions. But a majority also appear committed to averting Mr Trump’s radical departure from the constitution’s promise of citizenship. The justices could thread that needle in three ways.

Trump's executive order denies citizenship to U.S.-born children unless one parent is a citizen or resident, has been challenged in court.

The U.S. Supreme Court has acted in a series of cases involving challenges to executive orders signed by President Donald Trump and actions by his administration since he returned to office in January.