LANSING, Mich. — Jerry Waterson spent four years punching and kicking his way through Michigan’s mixed marshall arts unregulated amateur system, where nearly anything goes and where fighters are often uninsured or could be infected with HIV or hepatitis.

Michigan is among about a dozen states in which amateur MMA fights are legal but unregulated. That could soon change, however, as even lawmakers who recoil at the sport’s brutality see the wisdom in setting ground rules.