Can denouncing evil only be done with the permission of the ruler?
Question

                Is it a condition for changing evil with one’s hand that one has the permission of the ruler?
Praise be to Allah.Denouncing or changing evil comes in stages, as stated in the hadeeth in which 
          the Messenger  (peace and 
          blessings of Allaah be upon him) said: “Whoever among you sees an evil 
          action, let him change it with his hand [by taking action]; if he cannot, 
          then with his tongue [by speaking out]; and if he cannot, then with 
          his heart [by hating it and feeling that it is wrong]…” This is general 
          and applies both to the one who is seeking to remove the evil and the 
          one who is being denounced; it does not apply to one and not to the 
          other. But it is essential to pay attention to circumstances: if seeking 
          to remove an evil will lead to an even greater evil, then it is not 
          permissible under any circumstances to denounce the one who is doing 
          it, whether he is a ruler or a subject. But if it is known that the 
          evil will be reduced and good will result from that if it is denounced, 
          then it must be done regardless of whether the one who is being denounced 
          is a ruler or otherwise, because this is what is implied by the hadeeth of the Messenger  (peace and blessings of Allaah be upon him). But it is not permissible to limit the meaning of the words of Allaah or the words of His Messenger  
          (peace and blessings of Allaah be upon him) without any sound evidence for doing so.