The Republic Justicars are agents entrusted with extraordinary authority by the Romulan Republic Electoral Body, including the power of life and death over the inhabitants of the galaxy. They form an elite group selected from a number of different races within the Republic, and their primary responsibility is to preserve security and stability by whatever means necessary. Though they are generally considered as being above the law and have complete discretion as to the methods used to accomplish their mission, an individual's status as a Justicar can be revoked by the Electoral Body in a case of gross misconduct. Justicars operate alone, supported by a hand selected staff. They may, on occasion, work with other Justicars according to the nature of a particular task and to their personal preference.

Justicars have no command structure. They answer only to the Republic Electoral Body, and in some cases the Electoral Body prefers not to know the exact details of how a Justicar accomplishes their mission. Justicars act in any way they see fit, either with careful diplomacy or ruthless force, being officially above any law. The assignment of a Justicar is often less contentious than a military deployment, but shows that the Republic government is aware of a situation.

Candidates for the Justicars typically have years of military or law enforcement experience before even being considered. The screening process typically involves background checks, psychological evaluations, and a long period of field training under an experienced mentor. In the event of a Justicar going rogue, the only solution is to revoke their status, then send another Justicar to apprehend them.