In order to prove police brutality, the plaintiff must first and foremost understand what the limits or guidelines are with regard to the use of force in the jurisdiction in question. To win the case, the plaintiff must convince a judge or jury that the police officer in question exceeded the amount of force allowable under the circumstances. Proving police brutality can be extremely difficult as the witnesses to the incident are frequently other police officers resulting in the plaintiff facing the blue wall of silence. A judge or jury will generally look at three things when determining if the officer overstepped his bounds: whether the plaintiff was resisting arrest and to what extent; was the plaintiff armed; and what force did the officer actually use to compel compliance by the plaintiff.
The definition of police brutality or excessive force can vary widely by jurisdiction. In some countries, use of force, even deadly force, is rarely questioned. Within the United States, there is not one clear definition of what constitutes excessive use of force. One possible definition looks to whether the officer reasonably believed the level of force used was necessary to accomplish a legitimate police purpose. The use of force is a highly subjective issue that is heavily dependent on every detail of the incident that gave rise to the need for force.
A claim against a police officer for police brutality will generally be investigated internally by the law enforcement agency itself before a plaintiff may file an actual court case. In many jurisdictions, this is a prerequisite to filing a formal complaint in a court. The internal affairs division will then do a thorough investigation and file its own report along with a conclusion as to whether the officer used excessive force or not. A conclusion that the officer did not commit police brutality does not prevent the plaintiff from pursuing the case in a court of law.
When force is used, the police officer will undoubtedly claim that the subject was resisting arrest. Any video or witness testimony to the contrary will help prove police brutality. If the subject was armed, then the police officer is almost always justified in using additional force, even if the subject does not actually use the weapon. The amount of force used by the police officer will be the biggest issue in the case and frequently the determining factor. Hospital reports, x-rays, photos of injuries, and, of course, witness testimony or video can be invaluable when proving that the amount of force actually used by an officer was unnecessary and amounts to police brutality.