Trump’s executive order, signed in January, seeks to deny citizenship to children who are born to people who are living in the U.S. illegally or temporarily. It is part of the hard-line immigration agenda of the president, who has called birthright citizenship a “magnet for illegal immigration.”

In 1898, in the landmark case of U.S. v Wong Kim Ark, the Supreme Court reaffirmed the birthright citizenship guarantee, clarifying that even if one’s parents were legally ineligible for U.S. citizenship, a child born on U.S. soil was a citizen.