Under the U.S. Constitution’s 14th Amendment, enacted in the wake of the U.S. Civil War to ensure that blacks previously subject to slavery had full citizenship rights, citizenship is granted to “all persons born or naturalized in the United States.”

It has been routinely interpreted over the years to confer citizenship to people born in the United States whose parents are illegal immigrants. “You cannot end birthright citizenship with an executive order,” Ryan, the top Republican in Congress, said in an interview with radio station WVLK, the Washington Post reported. The legal argument espoused by conservative activists for excluding children of illegal immigrants would likely be based around the language in the 14th Amendment that says people born in the United States are citizens if they are “subject to the jurisdiction” of the United States. This case, together with the clear meaning of every other part of the Citizenship Clause — except for that tricky "subject to the jurisdiction thereof" part — form the bulk of the strongest arguments for birthright citizenship: To supporters, it's in the 14th Amendment, and the Supreme Court appears to have squarely decided the issue. Saikrishna Prakash, a conservative legal scholar at the University of Virginia, said Trump faces long legal odds to ending citizenship as a birthright.
U.S. President Donald Trump vows to revoke the right to automatic citizenship given to children born on United States land to illegal immigrants. According to most authorities, birthright citizenship in the United States is protected in the Citizenship Clause of the Fourteenth Amendment to the United States Constitution.