The MASON System is a game program published and developed by the fictional ESG Studio. The program is first seen in the Ace Attorney series at the beginning of Turnabout Succession in Apollo Justice: Ace Attorney, although it does not actually become playable until later in the episode. It is an element of the Jurist System implemented into the trial of Vera Misham and, in-universe, resembles a video game in which the jury must traverse different locations across two different time periods, "seven years ago" (2019, after the trial of Zak Gramarye) and the "present day" (2026, before and during the events of Apollo Justice: Ace Attorney).