You can, just the same as you can drink a drink or eat a sausage roll.... but they can still get you under other traffic laws anyway if they deem you to be driving without due care and attention (etc) as a result. My mum got stopped ages ago for eating whilst driving - but she just got a telling off 'on this occasion'.
I'm not a big fan of blanket camera enforcement! A police officer can determine if the offence resulted in a loss of control or not! Just giving a line of motorists a ticket doesn't actually accomplish much other than raising funds.
I suppose we are talking about it though so it might be a deterrent to those stupid enough to try but I still think it's harsh to target motorists for doing this in this way.
Where's the targeting? People caught using phone whilst driving. Offence committed. Everyone knows you can't use a phone when driving so if you do then don't bitch when caught.