In a 7 to 2 vote, the court ruled that the law was in violation of free speech provisions in the US Constitution, or what’s left of it. Justice Antonin Scalia said that minors are entitled to a significant degree of First Amendment protection and that the government has no power to restrict the flow of ideas to which they may be exposed.
The law prohibited the sale of violent games to minors, but it was rather vague. It stated that violent games were those that in the opinion of a “reasonable person” appealed to a deviant or morbid interest of minors, or were offensive to prevailing community standards and lacked serious literary, artistic, political or scientific value. Judging by the last bit, it should also be perfectly legal to shut down Hollywood and send Michael Bay to a gulag in Sarah Palin’s home state.
On another note, despite the ban on violent games for under-18s, it was still perfectly legal for 17-year-olds to enlist in the US Marine Corps.