In my jurisdiction (New Jersey), all cameras, telephones or radios, and electronic or analogue recording devices are already banned from courtrooms unless expressly permitted by the Court. The court does it for the following reasons: (1) they interfere with the stenographers' equipment (very true in the case of the 2-way radios used by messengers), (2) it may violate gag orders or the rules that pertain to cases involving families, children, crime, or trade secrets, and (3) it is within a judge's discretion to set the required level of decorum expected before a court (i.e., some judges require all attorneys to wear suits, most require all present to remove their hats, and all require no noise or distractions [and here the issue of pda's without silent alarms, cameras, phones, and radios are addressed] during a proceeding). It's not a matter of controlling communication. It's a matter of maintaining a level of respect for the Court.

TPB, Esq.
Unbillable Hours.