Each time police officers draw their weapons, they step into a rigidly defined world where written rules, hours of training and Supreme Court decisions dictate not merely when a gun can be fired, but where it is aimed, how many rounds should be squeezed off and when the shooting should stop, says the New York Times. A grand jury will decide whether the Ferguson, Mo., police officer who fatally shot an unarmed African-American teenager two weeks ago followed his department’s 12 pages of police department regulations that govern officers' use of force.
But deciding whether an officer acted correctly in firing at a suspect is not cut and dried. A host of outside factors, from the officer's perception of a threat to the suspect's behavior and even his size, can emerge as mitigating or damning. Says one expert, “If a police officer has an objectively reasonable fear of an imminent threat to his life or serious bodily harm, he or she is justified in using deadly force.” “Objectively reasonable” is a standard set by the Supreme Court in 1989 when it said that a police officer's use of excessive force must be seen in the context of what reasonable officers would do in the same situation.