What is the ruling on studying man-made laws and teaching them?

Allah has made it obligatory to rule by His Sharia (Islamic Law) and has warned against seeking judgment from other than it. He, Glory be to Him, has also informed us that every judgment other than His judgment is a judgment of Jahiliyyah (pre-Islamic ignorance). Scholars of law and those who teach it are divided into three categories:

1. The first category: Those who study laws or teach them with the aim of understanding their reality, or to demonstrate the superiority of Sharia over them, or to benefit from them in ways that do not contradict the Sharia. There is no blame upon them for this. They may even be rewarded if their intention is to expose the flaws of man-made laws and the excellence of Sharia rulings. 2. The second category: Those who study laws or teach them in order to rule by them or to assist others in doing so, while believing in the prohibition of ruling by other than what Allah has revealed. These are fussaq (transgressors), and in them is minor kufr (disbelief), dhulm (injustice), and fisq (transgression), which do not take them out of the fold of Islam. 3. The third category: Those who study laws or teach them while deeming it lawful to rule by them, whether they believe Sharia is superior or not. This category is guilty of major kufr (disbelief) by the consensus of Muslims, because they have deemed lawful that which is known by necessity to be forbidden in Islam.