Because the ban is a secondary offense police cannot make a traffic stop if they see someone using their cell phone while driving, but all they need is some other reason to stop the driver and then they can hand them a ticket for violating the ban as well.
Distracted driving is quickly gaining the attention of law makers around the country as insurance providers and safety experts tout the benefits of driving without distractions. In December 2011 the National Transportation Safety Board released a reported stating that distracted driving, primarily texting and using a handheld device, was responsible for more traffic fatalities than even driving under the influence of alcohol and drugs. The NTSB called for an immediate nationwide ban on the use of handheld devices by all drivers, citing their report as proof that distracted driving kills and a ban would immediately begin saving lives.
Some states have since enacted their own bans on the use of handheld devices; others already had partial or complete cell phone bans in place prior to the report. Other states have been much more reluctant to enact bans on the use of cell phones by drivers because they feel the issue is best left to municipalities. This is what forced the hands of the Chapel Hill Town Council, although even they were not all convinced. The recent ban passed only barely with a vote of 5-4.
Chapel Hill is home to the University of North Carolina, meaning there a great number of younger, inexperienced drivers on the road during certain parts of the year. No doubt the new ban will at least prevent a few accidents as drivers are more or less forced to pay attention to the road, not the phone.