The law against texting while driving in Colorado began with a tragedy. Last year, nine-year-old Erica Forney was riding her bicycle in Fort Collins; she was killed by a driver police say was distracted by using a cell phone.

On June 1, Gov. Ritter signed a bill outlawing texting for all drivers. The bill outlaws all cell phone use for drivers 18 and younger while behind the wheel. It also prevents drivers with instruction permits, regardless of age, from using cell phones while driving.

Critics argue that the bill doesn't go far enough to protect Colorado motorists from distracted drivers. A bill before the state legislature would require hands-free accessories for all drivers using cell phones. It would prohibit drivers under 18 from using cell phones while driving, even those with hands-free accessories. It would also completely ban cell phone use by school bus drivers and motor vehicle carriers regulated by the public utilities commission.

A growing body of research shows how dangerous cell phone usage can be while driving. A survey by the AAA Foundation's Traffic Safety Culture Index shows that over half of U.S. drivers admit to using a cell phone while driving and that one in seven admits to sending text messages while behind the wheel.

Those numbers rise dramatically among young drivers, however. Nearly half of drivers 18-24 years old report text messaging while driving, while just over one-quarter of drivers between 25 and 34 admit to texting behind the wheel.

In one study, researchers used a driving simulator to compare the driving performances of drivers using cell phones to drivers who were not using cell phones, but were given alcoholic beverages until their blood alcohol level reached 0.08, the level at which a driver can be arrested in all 50 states for driving while intoxicated. Researchers found that cell phone users were actually more likely to cause rear-end collisions than the drunken drivers.

Researchers said that cell phone use has a dramatically negative impact on the reaction times of drivers.