Ruling on one who rules by something other than that which Allaah has revealed
Question

                Are the rulers who rule by something other than that which Allaah has revealed considered to be kaafirs? If we say that they are Muslims, then what do we say about the aayah (interpretation of the meaning):  

“And whosoever does not judge by what Allaah has revealed, such are the Kaafiroon (i.e. disbelievers — of a lesser degree as they do not act on Allaah’s Laws” [al-Maa'idah 5:44] ?
Praise be to Allah.The rulings on those who rule by something 
          other than that which Allaah has revealed vary according to their beliefs 
          and actions. Whoever rules by something other than that which Allaah 
          has revealed, thinking that it is better than the sharee’ah of Allaah, 
          is a kaafir according to all the Muslims. The same applies to the one 
          who refers for judgement to man-made laws instead of the laws of Allaah 
          and thinks that this is permissible. Even if he says that referring 
          for judgement to the sharee’ah is better, he is still a kaafir because 
          he has permitted that which Allaah has forbidden.
 But the one who rules 
          by something other than that which Allaah has revealed because he is 
          following his own whims and desires, or because of a bribe, or because 
          there is enmity between him and the one against whom judgement is being 
          passed, or for other reasons, knowing that he is disobeying Allaah by 
          doing so and that he should refer to the laws of Allaah for judgement, 
          is considered to be a sinner, one who is guilty of a major sin. He is 
          considered to have committed an act of lesser kufr, lesser wrongdoing 
          (zulm)  and lesser rebellion (fisq), as was narrated 
          from Ibn ‘Abbaas (may Allaah be pleased with him), and from Taawoos 
          and a group of the righteous salaf. This is well known to the scholars. 
          And Allaah is the Source of strength.