On January 20, 2015, Michael J. Davidson, MD, a cardiothoracic surgeon, was fatally shot on the premises of the Brigham and Women’s Hospital in Boston, Massachusetts. In the year leading up to this tragic day, a total of 14 active shooter incidents occurred in hospitals throughout the United States, leaving 15 fatalities in their wake. This reality and its potential amplification by copycats has reignited the debate over the adequacy of current and future hospital security arrangements. In this Viewpoint, we discuss the evolving frequency of hospital-based active shooter incidents, the relevant legal framework, and the role of hospitals and physicians in countering this threat.