San Jose, Calif. ? Gov. Arnold Schwarzenegger signed a bill Friday that makes it illegal to sell or rent violent video games to minors in California.

The signing of the bill, authored by Assembly Speaker Pro Tem Leland Yee, shows how far the video game industry has fallen out of political favor in a few short months. California joins Illinois and Michigan in passing an anti-violent video game bill in the past year alone, and similar bills have been proposed in just about every state, even though the courts have found prior prohibitions unconstitutional.

The law takes effect Jan. 1, although the video-game industry is already vowing to challenge it in court.

The governor said in a statement, “Today I signed legislation to ensure parent involvement in determining which video games are appropriate for their children. The bill I signed will require that violent video games be clearly labeled and not be sold to children under 18 years old. Many of these games are made for adults, and choosing games that are appropriate for kids should be a decision made by their parents.”

Yee’s bill stalled last year and again in the spring in the Assembly, but it passed easily this time. Yee said in an interview that many legislators were ready to sign on the heels of the video game industry’s worst public relations gaffe: Hidden sex scenes were uncovered this summer in “Grand Theft Auto: San Andreas,” causing the game’s maker to pull the game from stores.

Until now, California stores have had only a voluntary obligation to restrict the sale of games rated for adults, and kids can walk into some stores and buy whatever they want.

The new law doesn’t use the game industry’s own rating system, which labels games as “mature” or “adults only” for those 17 and up. Yee said that courts have held that states can’t endorse a private industry rating system.

Instead, the bill bans the sale or rental of “violent video games” to minors, where such games are defined as those that include killing, maiming, dismembering or sexually assaulting an image of a human being. The bill says the game’s sale to minors would be banned if a “reasonable person, considering the game as a whole, would find appeals to a deviant or morbid interest of minors.”

The law also classifies a game as subject to the ban if the violence in it is “patently offensive,” “cruel,” “depraved,” or “heinous.”

Opponents said this will lead to confusion about which games are affected and will lead to case-by-case decisions by juries. But Yee said that retailers themselves won’t be held responsible for categorizing games. The burden, he said, falls on the game publishers or their distributors to put 2-inch-high “18” labels on the games that have such violent images in them.

Asked if the ban would cover the games based on the governor’s own movies, such as the “Terminator” games rated “teen” for ages 13 and up, Yee said he didn’t expect that teen games would wind up being banned under the new law’s categorization.

Based on studies that show that violent games make children more aggressive, various teacher, medical, psychological and youth groups supported the legislation. But the game industry cites various studies that suggest there’s no harm from playing violent games.

The law will lead to legal challenges from the game industry’s trade group, the Entertainment Software Association, which notes that no such ban applies to violent movies or racy music.

“We are disappointed that politicians of both parties chose to toss overboard the First Amendment and free artistic and creative expression in favor of political expediency,” said Doug Lowenstein, president of the ESA, in a statement. “The ESA intends to file a lawsuit to strike this law down and we are confident that we will prevail.”

Industry representatives on Friday were critical of the governor as well as the legislation.

“It’s kind of ironic he’s protecting kids from himself,” said Jason Della Rocca, executive director of the International Game Developers Association. “It’s an interesting public relations move where he bunches together all these things to protect children. We are seeing continuing ignorance on the part of politicians and critics on the games industry.”