Laws in 30 states, District of Columbia, and federal government ban texting while driving, but they are difficult to enforce. Software for smartphones disables texting, e-mailing and Web-browsing while the vehicle is moving, taking the driver out of the equation.
Background
iZup, tXtBlocker, ZoomSafer and CellSafety disable cellphones when vehicle is moving
Some apps have opt-out features for passengers