Prodded by an attorney, Miami-Dade County Schools has banned the use of video games on school computers.

“Use of school board computers to play games of any sort, especially such games as Doom and Quake, is specifically prohibited,” Superintendent Roger Cuevas wrote in a June 2 memo to the district’s 330 schools.

The policy change was made in the nation’s fourth-largest school district after attorney Jack Thompson claimed the games were being played during school hours at one and possibly three Miami high schools.

Thompson represents the families of three girls killed in a West Paducah, Kentucky, high school in December 1997. A psychologist reported that the gunman, Michael Carneal, was profoundly influenced by the violent games Doom and Quake.

Miami-Dade school district spokesman Henry Fraind said he could neither confirm nor deny that the games were installed on some school system computers. But, he said, anyone who violates the order will face disciplinary action.

Meanwhile, the Interactive Digital Software Association, a Washington, D.C.-based game publishers lobbying group, is working with retailers across the country to develop a voluntary ratings system for games. As games are scanned at the cash register, a digital beep will sound for games rated “mature,” prompting a clerk to ask for identification. Those under 17 would not be allowed to purchase the games without parental consent.

The system is expected to go into effect in Washington state this summer and later expand into other states.