A group of academics is urging a US appeals court to strike down a law restricting children's access to violent video games.

The 33 scholars, from institutions including the Massachusetts Institute of Technology, the University of California at Los Angeles and the University of London, have described the law as misguided.

"Most studies and experiments on video games containing violent content have not found adverse effects," a brief lodged with the court said.

"Researchers who do report positive results have generally relied on small statistical differences and used dubious 'proxies' for aggression, such as recognising 'aggressive words' on a computer screen.

"Experts on childhood and adolescence have long recognised the importance of violent fantasy play in overcoming anxieties, processing anger and providing outlets for aggression."

The brief follows a decision by a federal court in Missouri to uphold an ordinance requiring parental consent for minors to purchase video games depicting graphic violence.