In the roughly 150 years since its enactment, one could count the serious examinations of America’s birthright citizenship guarantee on one hand. But as of this month, you’d need another hand. In one of his first acts upon reentering the White House, President Donald Trump signed an executive order ending universal birthright citizenship. Within hours, several lawsuits followed, claiming that the order is unconstitutional.

Every state with a Democratic attorney general has sued the Trump administration to block an executive order seeking to undermine the birthright citizenship protections guaranteed by the Constitution. Catch up quick: Trump's order would end birthright citizenship for children born in the U.S. to noncitizen parents and unauthorized immigrants. • The order also applies to parents who are in the country legally but temporarily, like foreign students, workers or tourists.

Future historians may judge that Executive Order 14156 marked the beginning of the end for American liberalism. But first, the American right must win the battle that President Donald Trump kicked off when he signed it. The order, which a U.S. district judge has temporarily blocked, ends birthright citizenship for those born on American territory to parents who are neither citizens nor permanent residents. Its title—“Protecting the Meaning and Value of American Citizenship”—points to its deepest purpose, which is not, pace the histrionics of liberal elites, to inflict suffering on...