Actually cell phone use is farther down the line on the main causes of car accidents. 98% of car accidents have been caused by a distracted driver. The main causes of these "distracted" accidents are as following (in order from biggest cause to smallest cause)
1. Rubbernecking (looking at other car accidents, police pullovers, anything like that)
2. Fatigued drivers
3. Looking at Scenery or landmarks
4. Passenger or child distractions
5. adjusting radio or other music form
6. Cellphone use.
There are other causes, but these are the notable ones. In reality, alcohol use is still the main cause of traffic collisions but is noted by the goverment as 'an accident' but rather as a crime and is also counted as the number 2 reason for distraction (passing out and all).
The law to ban cell phone use has been debated about for years, and if, as you say, it is the number 2 cause, why hasn't it been enforced? It hasn't because cellphone use is only a negligable cause of distraction at 5%. Being that only 25% of people on cell phones get into accidents this brings the percentage of accidents caused by cellphones to 1.1%.
Even though the accidents seem minimum it still attributes to over 200,000 injuries due to traffic accidents a year! In most of the cases another driver was involved and it wasn't because of reckless driving on the cellphone users part or lack of control that the accident happened (in most cases). Cellphone use makes a 35 year old driver have the reaction time of a senoir citizen, dropping their reaction time to hitting the breaks by 18%, and there regaining spped time (from braking) by 17%. Most cell phone related accidents are caused by another reckless driver and the cellphone user not being able to react in time.
So there's your statistics. In my opinion, yes, cell phones should be outlawed. But in all fairity if they are then so should passengers, children, animals, looking out your drivers side window when not turning or braked, rubbernecking, music, and being tired while driving.
EDIT: It has been found that there is no difference between regular cellphones and hands-free cell phones and the accidents caused by them. It is the distraction not the occupying of the hands that is a problem.