Dave, the Ohio law is a joke. It's a secondary offense, which means they have to pull you over for something else before they can cite you for the texting, just like the worthless seat belt law. But, it shouldn't be hard to find another offense to pull these idiots over for, i.e., turn signal violation, speeding (if you see them texting, pull them over if they even go 1 mph over), tailgating, failure to maintain lane. The other part of the law that's a joke is that it's a primary offense for anyone under 18. So, if you are under 18, you can be pulled over for texting. How does the cop know they are under 18? Also, why can't they use the existing distracted operation law? I believe there is also a loophole for LEOs and emergency use. I think I've heard of situations where they pull people over for speeding, give them a warning on the speeding, but cite them for the seat belt violation. So they don't even have to cite them for the primary offense to cite them for the secondary, just have another reason to pull them over.
I have to believe, though, that a hands-free only, primary offense law works (provided it's enforced). Last year I was in Chicago, riding the rapid transit train that is in the median of the expressway and noticed no one was talking on the phone. They have a hands-free only, primary offense law.