Great article from the COPS Office at the US Department of Justice on the use of force.
Some good quotes from the article:
The International Association of Chiefs of Police (IACP) in its study, Police Use of Force in America 2001, defined use of force as “The amount of effort required by police to compel compliance by an unwilling subject.”
The Bureau of Justice Statistics (BJS) in Data Collection on Police Use of Force, states that “…the legal test of excessive force…is whether the police officer reasonably believed that such force was necessary to accomplish a legitimate police purpose…”
“there are no universally accepted definitions of “reasonable” and “necessary” because the terms are subjective. A court in one jurisdiction may define “reasonable” or “necessary” differently than a court in a second jurisdiction. More to the point is an understanding of the “improper” use of force, which can be divided into two categories: “unnecessary” and “excessive.” The unnecessary use of force would be the application of force where there is no justification for its use, while an excessive use of force would be the application of more force than required where use of force is necessary.”