The US Supreme Court dealt a major blow to President Donald Trump's immigration agenda on Tuesday, striking down his executive order seeking to end birthright citizenship for children born in the country to parents who are undocumented or hold temporary legal status. In a 6-3 ruling, Chief Justice John Roberts wrote for the majority that children born on US soil to parents unlawfully or temporarily present remain "subject to the jurisdiction" of the United States and are entitled to citizenship at birth under the 14th Amendment's Citizenship Clause. Trump's order, signed on his first day back in office in January 2025, never took effect, having been blocked by every lower court that reviewed it β€” with one judge calling it "blatantly unconstitutional." The administration had argued that the phrase "subject to the jurisdiction thereof" in the 14th Amendment excluded certain immigrant groups, and that citizenship should apply only to those with allegiance to the US "by virtue of domicile." Solicitor General John Sauer also invoked concerns about so-called birth tourism. Roberts' opinion leaned on the landmark 1898 case of Wong Kim Ark, in which the Court ruled that a man born in San Francisco to Chinese immigrant parents was a US citizen by birth β€” an interpretation that has held for more than a century, surviving even periods of intense hostility toward immigrants, including the internment of Japanese Americans during World War II. Three conservative justices dissented, with Justice Samuel Alito writing that "the Court has made a serious mistake." Legal advocates hailed the decision as a landmark defense of constitutional limits on executive power. Cecillia Wang, national legal director of the ACLU, who argued the case before the Court, called it a victory "for all of us and the American people." Immigration law experts noted the ruling reaffirms a century-old reading of the 14th Amendment and signals that presidential authority over immigration is not unlimited, even amid heightened political polarization. Trump called the ruling "too bad for our country" and, in a pointed jab, said the decision represented a "massive" win for China. He has pledged to pursue legislation in Congress to achieve the same goal, though legal experts β€” including some Republican officials β€” have cast doubt on whether Congress can override what the Court found to be a constitutional guarantee. Hours after the ruling, the Justice Department directed US attorneys to prioritize prosecuting so-called "birth tourism schemes." The ruling comes as the country approaches the 250th anniversary of American independence, reaffirming a definition of citizenship rooted in the 14th Amendment's post-Civil War origins, when it was ratified in 1868 to secure citizenship rights for formerly enslaved Black Americans.