Criterion is a Unified Earth Government colony world. It was attacked by the Covenant near the end of the Human-Covenant War in 2552. It was defended by both the UNSC Army and the Marine Corps. Gabriel Thorne, then serving in the Army, participated in the battle, during which he single-handedly saved his entire platoon.
After hijacking a Covenant Spirit to exfiltrate from Imber, ODSTs Staff Sergeant Malcolm Geffen, Corporal Vasily Beloi, and Emanuel Barakat left the dropship on Criterion. In 2553, while selling an MA5B assault rifle to an arms dealer on Venezia, Vasily wondered if the Spirit was still there.