Originally Posted by Last Island

@ Unsolved Mystery

If an Imam (leader) or Amir (ruler) becomes corrupt he should first be given a call to Islam (submission) in private, or possibly in public if his evil deeds were done in public. If he does not turn away from his evil deeds, he should be overthrown or removed from position. However, in the process of removing him from position, he should not be physically fought, such as waging war with weapons. This is because the ruler is still muslim, and the muslims are not to attack or kill another muslim. If, however, the Muslim eader or ruler completely abandons his salat, he nullifies his Islam and can be fought if necessary. (However, to prove this, it would take an Islamic court or similar situation in which the person could defend themselves against all accusations).

Hadith - Sahih Muslim 4569, Narrated Umm Salamah, R.A.

The Messenger of Allah (peace be upon him) said: In the near future there will be Amirs (rulers) and you will like their good deeds and dislike their bad deeds. One who sees through their bad deeds (and tries to prevent their repetition by his hand or through his speech), is absolved from blame, but one who hates their bad deeds (in the heart of his heart, being unable to prevent their recurrence by his hand or his tongue), is (also) safe (so far as God"s wrath is concerned). But one who approves of their bad deeds and imitates them is spiritually ruined. People asked (the Prophet): Shouldn't we fight against them? He replied: No, as long as they say their prayers.