Lex regia
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
The royal or imperial law. A law enacted (or supposed or claimed to have been enacted) by the Roman people, constituting the emperor a source of law, conferring the legislative power upon him, and according the force and obligation of law to the expression of his mere will or pleasure.
See Inst. 1, 2. 6; Gaius, 1, 5 ; Mackeld. Rom. Law, § 48; Heinecc. Rom. Ant. 1. 1, tit. 2, §§ 62 —67; 1 Kent, Comm. 544, note.