system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] During the time of the Republic, was it illegal to just be a Sith?
gpt
Yes, and then no. 

More specifically, in Legends there was an Anti-Sith Law, but it was repealed a little while before the start of the Clone Wars. In both canons, Mace Windu's attempted arrest of the Supreme Chancellor was basically deemed unconstitutional. Of course, Windu was actually arresting Palpatine on conspiracy, not on the basis of his religion.