Federal reserved water rights are a product of United States Supreme Court precedent stretching back to the turn of the 20th century. Namely, the Supreme Court originally held that the doctrine derives its authority from the Commerce Clause, Art. I § 8, and the Property Clause, Art. IV § 3, of the United States Constitution which together enable federal regulation of federal lands (Cappaert, 426 U.S. 128, 138). However, the more commonly accepted constitutional basis for FRWR has been placed in the Property Clause acting in concert with the Supremacy Clause, Art. VI § 2. The first of these allows the federal government, as an ordinary landowner, to use navigable and non-navigable waters on public lands. The latter overlays this with the federal government’s ability to assert water rights that trump state claims because of its position as a superior sovereign.