The HOS cites the tragic death of an Ashburton couple to call for a ban on cellphone use in cars. The driver who killed them was texting. It is worth noting though that he also was over the legal drink drive limit and also drove through a stop sign which is also illegal.
Did a cellphone kill them? No. A young 19 year old driver who was twice his legal drink drive limit who went through a red light did.
We already have a law which makes it an offence to use any object in a way which distracts you from safe driving. This covers all distractions such as food, drink, radio tuning, cigarette lighting, book reading etc.
Sending a text while driving is stupid and if a cop sees you doing it, you should be charged. But that is different to saying it should be illegal to (for example) answer a call on a hands free cellphone while stuck in traffic and moving at 20 km/hr.