Not sure on the Mass. Law, but here in Connecticut, the law specifically allows drivers to interact with a Navigation system. So just make sure waze is visable on your screen if you get pulled over.
" "Mobile electronic device" means any hand-held or other portable electronic equipment capable of providing data communication between two or more persons, including a text messaging device, a paging device, a personal digital assistant, a laptop computer, equipment that is capable of playing a video game or a digital video disk, or equipment on which digital photographs are taken or transmitted, or any combination thereof, but does not include any audio equipment or any equipment installed in a motor vehicle for the purpose of providing navigation, emergency assistance to the operator of such motor vehicle or video entertainment to the passengers in the rear seats of such motor vehicle. "http://www.cga.ct.gov/2010/ACT/PA/2010P ... 427-PA.htm