The idea of tying liability protection to doctors' adherence to best practices in medicine has become increasingly popular in the health care reform debate. In this new commentary for the Manhattan Institute's Center for Medical Progress, Joseph Bernstein (Penn) and Duncan MacCourt (U. Mass.) develop the safe harbor idea and summarize a proposal to address its federalism difficulties: the establishment of state-by-state Societies for Quality Medicine to promulgate standards of care and best practices.