Police release dashcam footage of traffic stop that led to fatal Walter Scott shooting

[Lurks Often]

2. Even if he was an alleged car thief, that is not sufficient legal justification for the shooting

Legally, there are a few situations where shooting someone in the back is justified:
The short version, is that someone is legally justified shooting someone in the back if the person fleeing can reasonably be considered a grave menace to the general public if allowed to escape. For example, preventing someone who just murdered someone right in front you from escaping, would be probably be considered reasonable in a courtroom.

A fairly extreme example, it would have almost certainly been legally acceptable to shoot Loughner in the back while he was shooting at all those people in AZ.

Hostage rescue would be another example when it would be considered legally acceptable.

There is ZERO evidence that Slager was justified in shooting Scott in the back