The main justification for this law?

[robkelk]

You know what else would prevent lynching?
Taking any person who participates in a lynching and throwing him in jail for the rest of his life. Continue this until people get the message that the government determines punishment, not the mob.

First they would need to build a jail...
--
Rob Kelk
"Governments have no right to question the loyalty of those who oppose
them. Adversaries remain citizens of the same state, common subjects of
the same sovereign, servants of the same law."

- Michael Ignatieff, addressing Stanford University in 2012