A federal appeals court on Monday upheld an injunction against a Minnesota law that targeted at children under 17 who rent or buy violent video games.

A three-judge panel of the 8th Circuit U.S. Court of Appeals agreed with a lower-court judge that Minnesota went too far when it passed its law two years ago because the state couldn't prove that such games hurt children.

The law would have hit kids under 17 with a $25 fine if they rented or bought a video game rated "M" for mature or "AO" for adults only. It also would have required stores to put up signs warning of the fines.

Game makers and retailers swiftly challenged the law, arguing it was an unconstitutional restriction of free speech. U.S. District Judge James Rosenbaum ruled in their favor in July 2006.

But the appellate opinion, written by Judge Roger l. Wollman, showed the judges weren't entirely happy about it.

"Whatever our intuitive (dare we say commonsense) feelings regarding the effect" of violent video games, precedent requires undeniable proof that such violence causes psychological dysfunction, Wollman wrote.

"The requirement of such a high level of proof may reflect a refined estrangement from reality, but apply it we must," he wrote.