In cases of police brutality, qualified immunity
is a legal doctrine based on two rulings by the Supreme Court. Qualified immunity requires lower court judges to ignore whether any laws were broken and dismiss the case, unless another police officer had been found guilty previously in a similar situation.
In fact, the situations need to be so similar that in one example, a judge threw out a case where police officers sicced an attack dog on a homeless man while he was surrendering by kneeling down with his arms above his head. The judge compared it to a case where police officers sicced an attack dog on a person while lying face down and concluded the two cases were not exact, therefore the police officers were not guilty.