The supreme court appears poised to reject Trump’s attack on a foundation of US identity. We must hope it follows throughAmerican opponents of birthright citizenship – the right of all those born on the soil of a country to claim full legal rights and political representation in that nation – like to point out that many countries don’t have it. On Wednesday at the supreme court, during the oral arguments in Trump v Barbara, the case challenging Donald Trump’s attempt to end birthright citizenship in the United States by executive order, the Trump administration’s solicitor general, John Sauer, claimed that “almost every country” denies birthright citizenship. Trump himself made the unusual choice to attend the oral arguments in person, signaling his investment in the issue and perhaps hoping that his presence would intimidate the justices into ruling in his favor. But he left soon after Cecillia Wang, a lawyer for the ACLU who represented his opponents in court, began speaking. Not lon...