Monday, September 17th, 2007 — A message from the state of California to its 16-and 17-year-olds: Dnt txt n drv — thx. A law signed by Gov. Arnold Schwarzenegger on Thursday will require those teens to put down all cellphones and other electronic devices while driving. Older drivers will be able to use hands-free devices but minors won’t enjoy that luxury — in part because of the popularity of text-messaging among teens.