I would rather live in a society with the odd domestic terrorist whacko than one where the government dystopically forces family members to turn one another in or else go to jail too.
I'm not against handling it but I could live with it a lot better if I handled the justice myself and dealt with the consequences of that afterward. I don't think I could ever offer a sibling, or spouse, to the kings men and feel right about it even if the 'ends' turn out right.