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.

As the Supreme Court prepared to hear arguments Thursday on whether to allow President Donald Trump's restrictions on birthright citizenship to take effect, he falsely claimed on Truth Social that the United States is the only country that offers such a right.