The results of a 1997 study that appeared in the New England Journal of Medicine stated that using a cellular device while driving puts you at a risk four times that of people not using a cell phone. There are certain laws making running red lights, and drunk driving illegal and imposing specific punishments; phoning in a moving vehicle should be no exception.
In the United States, it is highly unlikely that legislation could be passed on the national level. There are only a few counties and towns that have passed traffic laws restricting cell phone use. Laws passed by counties and towns have had some effect in the past, but it makes more sense to legislate at the state level. Local laws don't have the same impact as state laws do.
In Japan, accidents linked to cell phones fell by 75% just a month after the country prohibited using handheld phones while driving. It is not possible to drive an automobile at high speeds, dial numbers and carry on a conversation without significant risks. If cell phone use is regulated then the roads will clearly be safer. Furthermore, cell phone use should be restricted on the roads to prevent reckless driving and negligence.