The US Supreme Court is hearing arguments in a case that could redefine one of the most significant questions in American law: Who is entitled to citizenship under the 14th Amendment under the Constitution. The focus has been on constitutional interpretation, including whether the citizenship extends to children of those unlawfully present in the US. This case exposes what Congress has failed to do, including allowing ambiguity to fester and allowing the courts to resolve disputes that are legislative in nature. The Citizenship Clause of the Constitution was not intended to function as a blank check, its central purpose was to guarantee citizenship to formerly enslaved persons who were subject to the full jurisdiction of the United States and owed it complete allegiance. If Congress believes birthright citizenship should extend to all persons born on U.S. soil regardless of their parents’ legal status, it should defend that position.