Proponents of the ban say it would protect witnesses from having their pictures snapped by "snitch" hunters carrying cell phones.
A person may not bring any electronic device into any court facility. -- Maryland's proposed policy
I hate to be the one bearing bad news but the Chinese, the Soviets and every other totalitarian regime has tried to restrict the flow of information but cyberspace knows no boundaries (except for the self-imposed ones companies have implemented when bowing down to kiss the feet of the Chinese dictators). The only entities that fear the public's access to information are those entities that have something they wish to hide.
Anyone arrested in this country has the right to a public trial -- and the public includes the blogosphere, Twitter, Facebook and other social media sites.