The South Carolina Supreme Court has issued a ruling detailing how jurors can use personal communication devices.

The South Carolina Department of Corrections on Friday used jamming technology to show that it could block cell phone signals inside prison buildings without affecting cell service outside.

The South Carolina Department of Corrections finds hundreds of cell phones inside its prisons, despite a ban on having them. It wants a change in federal law to allow it to block cell phone signals within prison walls.

Jamming the signals is against federal law, but Federal Communications Commission spokesman Robert Kenney said Thursday the agency understands concerns about prisoners using contraband cell phones.