Video games makers of games that depict graphic death and mayhem have told a US judge that they cannot be held responsible for copycat killers.
Lawyers for the eight - Acclaim, Activision, Capcom, Eidos, Infogrames, Interplay, Nintendo of America, and Sony Computer Entertainment America - say their content is protected under US free speech rules.
Eight firms are fighting a class-action lawsuit bought by the families of the victims of the April 1999 Columbine High School massacre that left 13 dead, including teacher Dave Sanders.
The action alleges that murderers Eric Harris and Dylan Klebold had been influenced by the marketing of video games, particularly Doom. The suit seeks £3.5bn ($5bn) in punitive damages for the family of Sanders and relatives of the other victims.
But lawyers for the software publishers this week filed a motion for dismissal. They argued that video games are protected as free speech and their makers cannot be held responsible for individual reactions to games.
"Even speech expressly advocating criminal activity (which the video games do not) cannot be the basis for liability unless the speech is directed to inciting imminent lawless action and likely to produce such action," the motion said.
The motion also said the lawsuit should be rejected because it does not allege that any one particular game provoked the tragedy.
Last year, US courts rejected a similar lawsuit filed by the relatives of the victims of a mass shooting in Kentucky.
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