The Ruling on One Who judges by Other than what Allah has revealed

Question:

Are those rulers who judge by other than what Allah has revealed considered disbelievers, and if we say that they are Muslims, then what can we say of Allah's Words:
And whosoever does not judge by what Allah has revealed, such are the disbelievers.?

Answer:

The rulers who judge by other than what Allah has revealed are divided into different categories, according to their beliefs and to their deeds. One who judges by other than what Allah has revealed, believing that it is better than the Law of Allah, is a disbeliever by consensus of all the Muslims, as is the one who judges by man-made laws instead of the Law of Allah, and claims that this is permissible. As for the one who judges by other than what Allah has revealed, because he finds it convenient to do so, or because of bribery, or due to enmity between him and the person being judged, or any other reason, in the full knowledge that he is acting in disobedience to Allah and that it is obligatory for him to judge by Allah's Law, he is considered to be one of the disobedient ones and a perpetrator of a major sin and he has committed minor Kufr (disbelief) and minor Thulm (wrong or injustice) and minor Fisq (disobedience) as has been reported on the authority of Ibn 'Abbas, may Allah be pleased with him, Tawoos and a number of the righteous Salaf. This is what is well known to the people of knowledge. And Allah is the Granter of Success.

Source:
Fatawa Islamiyah, Vol. 1 Pages 113-114