It’s not that no one will be badly hurt, Glaser Safety Slugs will kill. What they won’t do, is go through the perp, through the wall, across the driveway, into the neighbor’s house and kill the neighbor’s dog as well.
I was referring to what your lawyer might say to a jury, not to their actual effectiveness. I imagine they are pretty effective because they expend all their energy on their target, rather than the walls (or people) behind the target.