The state of South Carolina is about 30% black
It's disproportionate, no question, but not clearly indicative of racially motivated use of the devices, especially since the department only deployed the taser 17 times.
I think there's a lot of room for discussion as to how hesitant a cop should be to deploy one of these devices to get control of a situation where he feels threatened. But I absolutely prefer using tasers on beligerent suspects like the woman in the video, when the alternative is dead or seriously injured cops and suspects.
It seems fairly clear, from what I understand, that she had full intent on remaining violent, and in that case, the use of the taser seems justified, and seems that its' use was fairly restrained. So I really can't say the use of the Taser was wrong here, unless something else shows otherwise.
Personally, I don't think it would have been appropriate to shoot someone being "violent," whether she'd drawn blood or not.
And really, that's what Tasers were originally supposed to be used for: situations in which the cop would otherwise be forced to draw a gun and apply deadly force. The Taser is somewhat less deadly than a 9mm pistol, but as we have seen, there is no way that "non-lethal" is an accurate description of the weapon.
So ultimately, in my mind Taser use is only justified in cases when the cop would have had no other option but to shoot somebody in order to resolve a given situation. It is absolutely not appropriate as an easier means of subduing an unruly individual. From what I can tell from these articles, none of these cases even come close to meeting that standard.