The use of force by police has proven to be a challenging and divisive issue in the United States, and for good reason. Philosophically, the government’s use of violence against community members is in tension with basic democratic norms of individual liberty, personal security, and bodily autonomy. In practice, officers use force on hundreds of thousands of individuals every year. Police violence plays an important role in shaping public attitudes toward government generally and toward policing specifically. Community trust and confidence in policing has been undermined by the perception that officers are using force, including deadly force, unnecessarily, too frequently, or in problematically disparate ways. The use of force can also serve as a flashpoint, a spark that ignites long-simmering community hostility. There are, in short, compelling reasons to think critically about police uses of force. This book explores an essential, but largely overlooked, facet of the difficult and controversial issues of police violence and accountability: the question of how society evaluates police uses of force. The authors—a prominent legal scholar and former officer, a long-time police commander, and a distinguished criminologist—draw on their experience and decades of research to offer five different answers to that question, discussing in depth the rules established by constitutional law, state laws, agency policies, international law, and community expectations, and providing critical information about police tactics and force options to allow for the accurate application of those analytical frameworks.