Why Police Officers Can Shoot You with Impunity

...well described here:

For answers, one has to look to the U.S. Supreme Court, which in 1989 ruled “that all claims that law enforcement officers have used excessive force -- deadly or not -- in the course of an arrest" should be "analyzed under the Fourth Amendment and its ‘objective reasonableness’ standard.” The late Chief Justice William Rehnquist wrote, “The question is whether the officers’ actions are ‘objectively reasonable’ in light of the facts and circumstances confronting them, without regard to their underlying intent or motivation.” 

In doing so, the court rejected the prior due process standard which was understood as force that “shocks the conscience” and had allowed for consideration whether the officer “acted in ‘good faith’ or ‘maliciously and sadistically’ for the very purpose of causing harm.”

The objectively reasonable standard leads to what look like callous outcomes -- like that of Crawford -- built on “because we can” not “because we had no choice” rules of engagement.

Today, if an officer says he feared for his life when a suspect dropped his hands to his waistband, even though he was just pulling up his pants, or was holding a toy gun in a discount store, not launching a massacre with an assault rifle, the officer would be justified in shooting someone to death.   (Walter Katz, New York Times)

Chief Justice Rhenquist was very much opposed to civil rights. For instance, he voted against desegregation.