The state of Louisiana had passed a law banning the sale of games to minors if an "average person would conclude that they appeal to a morbid interest in violence". It also banned the sale of games to minors which depicted violence which was "patently offensive" to an adult and are without artistic, political or scientific value.
The law is the latest in a string of state laws banning games which have been overturned by the courts. Brady ruled that banning the games would violate the free speech rights of game producers, retailers and players.
Brady rejected the arguments made by the pro-ban lobby that violence in games was more dangerous because games are interactive, which they said was more likely to encourage copycat behaviour. "This argument has been rejected many times before," wrote Brady.
He also said that he did not accept that the games could cause psychological damage to minors. "The state may not restrict video game expression merely because it dislikes the way that expression shapes an individual's thoughts and attitudes," he said.
The disputed law included penalties of $2,000 for retailers who sold games to minors or a year in prison, or both.
Recent cases in California, Illinois, Michigan and Minnesota have ended in similar verdicts.
President of the Entertainment Software Association Douglas Lowenstein criticised the passing and defending of the law. "In the post-Katrina era, voters should be outraged that the Legislature and governor wasted their tax dollars on this ill-fated attack on video games," he said in a statement.
Louisiana Governor Kathleen Blanco said that the burden of protecting children must now fall to parents. "I'm calling on all parents to diligently monitor the video games that their children are allowed to play," said Blanco in a statement. "If the courts can not protect our children, then we need to do it by rejecting the merchant of violence."