This is from back in 2014. This is not a good use of a Taser. It actually makes cuffing him harder. The two really hard parts -- getting a guy out of a car and getting hands out from under a resisting person -- are done.
This the guy is still resisting, so it's probably legal and departmentally justified. But it's morally and tactically wrong. He was seconds away from being cuffed.
I also just heard some rumor regarding the S.C. shooting (and I don't know if it's true) that Slager somehow ended up with a taser dart in himself. I only this mention because even if Scott had Tased Officer Slager, it doesn't matter. And I don't think that did happened Based on the video, if a dart did end up in Slager's leg, it seem more he somehow tased himself. But it's irrelevant because it doesn't change the issue about pulling the trigger on a man who was not a threat at the time you pulled the trigger. I'm curious about what led up to the shooting, naturally, but it doesn't matter. Slager was dead wrong.