Illegal Alien advocates commonly refer to illegal aliens as “undocumented.” It’s a verbal sleight of hand to diminish the perception of their lawbreaking, and make their presence look like nothing more than a lack of paperwork. The papers they lack, of course, are those which would grant them the legal right to reside in the U.S.
Furthermore, as Robert Law at the Center for Immigration Studies points out, the term undocumented is not an apt description for illegals because they commonly have many documents. Among them, he notes, are:
(1) a birth certificate from their home country; (2) a passport, driver’s license, or some other form of identity document from the home country; (3) a notice to appear (NTA) issued by U.S. immigration officials upon detaining the alien; (4) a visa permitting the alien into the U.S. under terms that he or she subsequently violated; (5) a fake U.S. passport, driver’s license, or other identity document; (6) a stolen U.S. passport, driver’s license, or other identity document; (7) an arrest record; or (8) a conviction issued by a U.S. judge.
Read more at cis.org