Against animals, maybe. As in you're scaring a bear from the yard.
Against humans "LESS lethal" ammo is only usable when you're backed up by another person using LETHAL ammo so if/when the less lethal fails the other person is ready to fire lethal ammo to prevent you getting taken out.
In most cases the law is simple......If you fire a gun at someone it doesn't matter if it's a load of buckshot or a load of goose feathers..... You've fired a lethal weapon at a human.
The situation BETTER be that someone's life or physical safety was at genuine risk enough to warrant firing at them.
If that's the case, legally and morally it doesn't matter if they live or die, that's on them.
As the late famed Bill Jordan said..."Like being pregnant, there's no such thing as shooting someone just a little. If you have to shoot someone, shoot 'em GOOD".
Figuring that you don't want to kill someone, so you'll shoot them with less lethal ammo is how you either.
A. Kill or seriously wound someone you didn't really intend to. (It's LESS-lethal, not NON-lethal).
B. Fail to stop someone who then kills you or your family.
If it's serious enough to shoot, it's serious enough to send the very best.....buckshot.
If not, you have no business firing a gun at someone no matter if it's just a blank.