Since 1993, several incidents of gun violence in the United States, such as the Columbine School shooting of 1999, put more blame on video games for inciting these crimes, thought there is no conclusive proof that violent video games lead to violent behavior. Under demands of parents and concerned citizens, federal and state governments have attempted to pass legislation that would enforce the ESRB rating systems for retail that would pose fines to retailers that sold mature-rated games to minors. This came to a head in the Supreme Court of the United States case "Brown v. Entertainment Merchants Association", which concluded in 2010 that video games were considered a form of protected speech, and regulation of their sales could only be mandated if the material passed the Miller test for obscene material.