The Matrix defense is a legal defense based on the premise of the film franchise The Matrix, in which reality is a computer generation and the real world is different from what reality is popularly perceived to be.
A defendant using this defense claims that they committed a crime because they believed that they were in a simulated world (the Matrix), and not in the real world.
A defendant could allege they never intended death for their victim because they believed the victim to be alive in the other reality.
This is a version of the insanity defense and considered a descendant of the Taxi Driver defense of John Hinckley, one of the first defenses based on blurring reality with films.
[1] Regardless of whether the defendant believes that they were living within a simulated world, this defense has been used in cases where the accused were sent to mental-care facilities instead of prisons: This article about a criminal law topic is a stub.