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.

The Supreme Court could create a patchwork of citizenship rules that echoes a dark time in the nation's history.

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.