State law here in Mass. My regular helmet is a (legal) half-helmet, and I carry a fullface in the saddlebag (Nolan trilogy outlaw) for inclement weather. I'm 43, and when I was younger I would take the helmet off as soon as I got to a state that allowed it (ME,NH, RI) As I got a little older, I started wearing a helmet on the highway, but would then take it off once off the highway. Now, with two kids, and a little older, I usually always ride with one on. I'm certainly pro-choice when it comes to helmets, though.