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 hears arguments in Trump v. CASA, Trump v. Washington, and Trump v. New Jersey, a case about judges stopping President Trump's executive order that limits birthright citizenship for children born to undocumented parents.