Well, that seems bad...

Okay, the government kills people in some states. The death penalty is still used, albeit enforced haphazardly.

If you must do it, there are bad, worse, and horrible ways to implement it. We tend to use the horrible ones. In this case, a firing squad in South Carolina was plainly not up to the task.

In the first modern death penalty carried out, Utah also used a firing squad (the prisoner was given a choice, and chose that). 

Utah used 5 volunteer police officers, behind a wall  25 feet away with a cutout for aiming and shooting. A bag was placed over the prisoner's head, and he was shot. One of the guns had blanks, so people didn't know who fired the "kill shot."

This year, South Carolina used a different system. They used 3 volunteers from the Department of Prisons, 15 feet away from the prisoner. Apparently, the Corrections Officers used either were absolutely horrible, or they purposefully did not shoot him in the heart. Instead, all three shots missed the mark, and the victim died slowly and painfully over a few minutes.

I think if we must have the death penalty, we should rethink it. Give the prisoner a bunch of pills and let him die. Or put him in carbon monoxide and let him die comfortably. The French guillotine, used until 1977, is also not terrible because it is quick and pretty fail-safe.

On the other hand, we in the United States use various means, defined by the state. Firing squad, electrocution (who can forget Florida's "Old Sparky"), or lethal injection. Lethal injection doesn't sound awful, but it doesn't always work or work quickly, because the countries that make the right drugs refuse to send them to the US. So we make do.

PS - England hung people until 1964. I think that is somewhere in the "worse" of the possible ways - but still below horrible.