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MASON System
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This article is written in an out-of-universe perspective due to its description of a feature used as a gameplay mechanic as well as a plot device. An in-universe take on how the MASON System is used can be found in the article Turnabout Succession.

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).


The MASON System appears as a chapter in Turnabout Succession in which the player takes on the role of Phoenix Wright as he attempts to piece together events in both the past and the present. It is very similar to investigation chapters with the exception that it has an "End Search" option, which takes the player back to the main MASON System interface, instead of a "Move" option, which brings up a list of locations. This is also the only part of Apollo Justice: Ace Attorney in which Phoenix Wright's magatama can be used, as Apollo Justice never uses it in the game. At the conclusion of the trial of Vera Misham, it is revealed that the player actually represents the jury, who played Phoenix Wright's "game" to come to the truth behind the case.

The player takes on the role of "Jurist No. 6" and is required to choose a verdict, which determines the ending of the case. The MASON System interface is used as the background in the Jurists' Chambers.

A notable feature of the MASON system is that, in order to progress, certain items from the "present" must occasionally be retrieved and presented to people in the "past". For example, Phoenix Wright must visit Kristoph Gavin in the present and examine his bottle of nail polish before he can present the bottle to Vera Misham in the past. This was most likely done to provide an easier logical path for the player or the jury. For instance, Wright's conversation with Gavin reveals that Wright suspected that Gavin was involved in the case somehow. Consequently, the sequence of events as they transpire for the player/jury in the MASON system is not a completely accurate representation of what actually happened.


The name may be a reference to Perry Mason, a fictional defense attorney who took seemingly hopeless cases and turned them into victories, often making the true criminal confess on the stand in much the same way that Phoenix Wright and Apollo Justice do. The acronym in ESG Studio may likewise be a reference to the author of the Perry Mason novels, Erle Stanley Gardner.

MASON System
Visitor's roomDefendant Lobby No. 2Wright Anything AgencyDrew StudioMasonpast
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Borscht Bowl ClubSolitary Cell 13Drew StudioSunshine ColiseumMasonpresent
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