The National Guard is withdrawing from Ferguson, Missouri. Darren Wilson, who won't face charges for killing Michael Brown, has resigned from the police force, saying he hopes this "will allow the community to heal." Attorney General Eric Holder is working on a plan to end racial profiling. And President Barack Obama, looking to build "community trust" in police, requested Congress for $75 million to help provide roughly 50,000 body cameras to state and local police departments.

The assumption is that cameras are objective, silent witnesses that provide indisputable evidence, and also that people behave differently when they know a camera is capturing their actions. And the implication is that, had the shooting death of Michael Brown been recorded, we'd know exactly what happened—and justice would be served.

The case of Eric Garner should put an end to this fantasy.

Video cameras are an old technology by now. They’ve been used to document police abuse against minorities at least since before Bull Connor, and since the days of Rodney King we have been able to see considerably more of the abuse, as cell phones and security cameras and dashboard cams keep track of encounters between the police and people of color. And yet, police brutality of black people persists. The only difference is that we are more aware of it.

After all, an amateur video did capture a white New York City police officer's chokehold on Eric Garner earlier this year, and the camera's presence changed neither the Garner's fate nor that of the officer. Garner is dead, and a grand jury voted Wednesday not to bring criminal charges against the officer, Daniel Pantaleo.