Irrational laws made, rationalised, and justificated.
If I was to interview a group of rape victims, I could probably gain a great deal of information supporting the need to ban any form of sexual contact between men and women. I could prove that sex between a man and a woman was "harmful". Allow a law that contends that sex is empirically a harmful and immoral act, and some time to propagate it, and a vast majority of the populace would fall readily into agreement. Moreover, proponents would invariably argue that the law was established rightly, and those who dissented from such an opinion would be considered criminals.
For this reason, it is next to impossible for the average person to be convinced of the need to repeal a law. Once the law has been established, popular consciousness is compelled to justify and support it. Authority cannot be wrong, lest civilisation fall into chaos.
As time passes, more laws are made to support and validate the irrational laws of past generations. Emotions run high on many topics. Myths form regarding a subject and social bigotry takes hold. The "black market" effect, wherein underground movements continually violate legislative edicts, cause support to grow in order to suppress opposition.
Violence is a natural outgrowth. The use of violence to enforce laws causes a backlash, as the oppressed retaliate. Every action has an equal and opposite reaction.
I am become death, destroyer of worlds