alt Hacker NewsYep, legality is just a concept of "the people who control the people with the guns on this particular piece of land decided that way".
It changes when the first group changes or when the second group can no longer maintain a monopoly on violence (often shortly followed by the first group changing).
I wouldn't be quite so pessimistic: hypocrisy is an important force.
Many times, people are perfectly willing to commit heinous acts, but less willing to write down the laws to make them legal.