Because the ratings system is entirely voluntary, some lawmakers say it is not enough to protect children from the harmful effects of virtual violence…

But it is unclear whether Congress could pass any restrictions that would pass muster with the courts.

Last year, the Supreme Court struck down a California law that banned the sale of violent video games to minors, ruling that the ban violated the constitutional right to free speech.

“Like the protected books, plays and movies that preceded them, video games communicate ideas — and even social messages,” Justice Antonin Scalia wrote in the court’s opinion.