Is it correct to assault and harass anyone regardless of free thinking and belief politically wise ?

What are the rules and laws ascribed to such eru units are there any procedures civilians and political activists should know and have recourse to in such events of adverse stop, harass and illegal entry and detention / arrest of such ? if so what are the clear defined rules and protections and lawful and legally constitutional rights to such unfortunate individuals not able to protect themselves in this matter of importance as a recent survey points to people being beaten and harassed in front of their children and family members in ireland ?