The word "PRIVILEGE" comes from latin privilegium, composed by "privus" (to oneself) and "legalis" (related to law). Refers to all that rights wich are obtained exclusively on one thing. In legal language privilegium  is a law that just affect to a particular sector of citizens or to a concret individual. Roman law  prohibits from the year 450 b.C. the fact that privilegia could be approved, or even the fact that someone proposes them to be approved in assembly. This prohibition is known as privilegia ne inrogatur and is the first written acknowledgment, in Roma, of the idea that law must be equal for everyone.