3 Feet for passing

I've always thought that it's illegal for cars to pass me leaving less than 3 feet between me and them. Unfortunately that doesn't seem to be true for Massachusetts. Here are the 21 that do.
MA does state that drivers need to pass bicyclists at a safe distance and speed, but does not prescribe what that safe distance/speed is. New Hampshire for example defines that to be 3 feet at 30 mph, adding a foot for every 10 mph increase in speed. Something like this is more effective in my opinion than the vague clause defined here.
On the positive side MA does have some decent laws to protect cyclists like dooring, cutting you off, the right to take the full lane, etc. The problem that I witness as a commuter, is that none of that is enforced. Mayor Menino has done an awesome job on his efforts to moving Boston to a first class bicycling city with all the new bike lanes and the bike sharing program. We still need much more enforcement on both cyclists and motorists to make this city a safer place to ride.