Before the federal Affordable Care Act (Obama Care) was passed, Massachusetts law required employers with 11 or more FTEs to offer health benefits to employees. The federal law preempted that, and only imposes this requirement on employers with 50 or more FTEs.
The Massachusetts law was never repealed. This means if the Affordable Care Act is ever repealed, the state requirements could come back into play, affecting many more small businesses than the current federal law.