Is it permissible for a judge who rules by other than what Allah has revealed to be an Imam?

The ruling is not uniform for those who practice judgeship under man-made laws. Some work to reduce injustice while acknowledging the obligation to rule by what Allah has revealed, while others deem violations permissible. Prayer behind a judge is valid if his adherence to Islam is established, even if he is a transgressor or an innovator, according to the preponderant opinion.