While the Patient Protection and Affordable Care Act (ACA) of 2010 promises to expand care to millions of Americans, how the bill will determine the meaning of medical necessity—the concept that continues to serve as the key means for regulating the utilization of health care services—remains an open question. Instead of detailing what is and is not considered medically necessary, the ACA charges the U.S. Secretary of Health and Human Services with overseeing the processes by which these critical determinations will be made. This article considers a series of “meta-questions” regarding the place of medical necessity determinations within the context of the ACA. It does so by examining the policy challenges presented by a bill that attempts to balance government regulation, physician autonomy, and the various market forces driving managed care. The result is an understanding of the inherently political nature of medical necessity determinations under the ACA.