Driving while using a hand-held phone has been a secondary offense in Maryland since 2010. It’s illegal, but you can only get a ticket for it if you’re being pulled over for something else. So it’s more like there’s a law against using a cellphone while driving with a taillight out, or using a cellphone while crossing the center line, or using a cellphone while unsafely passing. And as far as I can tell, Maryland drivers have been acting accordingly.
But the Senate and House have each approved a separate bill that would make the use of a cellphone while driving a primary offense, meaning you don’t need to be also blowing red lights or throwing garbage out the window to risk getting a ticket for it. So the time may come when you will have to really, really, really put down that phone, Maryland.