The key to both of the legal standards — defense of life and fleeing a violent felony — is that it doesn’t matter whether there is an actual threat when force is used. Instead, what matters is the officer’s “objectively reasonable” belief that there is a threat.
…There are plenty of cases in which an officer might be legally justified in using deadly force because he feels threatened, even though there’s no actual threat there.
…That puts a lot of weight on an officer’s immediate instincts in judging who’s dangerous. And those immediate instincts are where implicit bias could creep in — believing that a young black man is a threat, for example, even if he is unarmed.