Just hang them

"Having said all this, if someone decided to gun down my entire family, I'm sure I could find it quite easy to reconsider my stance."

Quite Frankly, so could I, but if someone massacred my family I'd justifiably be having a fit of rage, I wouldn't be in a position where i'd be thinking clearly. That is why we have impartial governments. Retribution is a fruitless exercise in hypocrisy. It makes perfect sense and seems just in that moment of rage, but once the smoke has cleared and you take a step back you realize that it won't do anything but cause more suffering. It won't bring your family back.