In Roman law, the Latin adjective privatus makes a legal distinction between that which is "private" and that which is publicus, "public" in the sense of pertaining to the Roman people (populus Romanus).
Used as a substantive, the term privatus refers to a citizen who is not a public official or a member of the military.
[1] Increasingly throughout the Middle and Late Republic, the privatus was nevertheless sometimes granted imperium during a crisis; the definition of crisis was elastic, and the amassing of power by unelected individuals (privati) contributed to the breakdown of the checks and balances of the republican system.
[2] The iudex privatus was a sole arbitrator or lay judge who conducted a civil case to which the parties had consented and who usually nominated him.
In the event that the parties could not agree on a judge, he was chosen from an official list of potential judges drawn up by the praetor.