GAM (Free Aceh Movement) is a group or movement in Aceh which was formed based on the disappointment of the Acehnese people towards the Indonesian government which was considered unfair and exploited the resources of Aceh's land so that the Acehnese people did not get welfare and prosperity. The long conflict between GAM and the Indonesian government ended with the signing of the Helsinki Memorandum of Understanding on August 15, 2005. Since then, GAM stopped its armed activities and transformed into a civilian organization through the Aceh Transition Committee (KPA) which then gave birth to the Aceh Party as an official political forum. In its development, the Aceh Party became a dominant political force in Aceh and was able to bring a number of ex-GAM figures to important positions in the regional government, including the position of governor. Thus, GAM's current position is no longer an armed movement, but rather an influential political force in the dynamics of the Aceh government. This transformation shows the shift of GAM's struggle from the military path to a democratic path through local political mechanisms. From the perspective of the four Imams of the Islamic School of Law, each with its own perspective on law, the research question is how do the Imams of the Islamic School define rebellion or separatism? Is GAM included in the criminal act of rebellion or also called separatism or not? How is GAM redefined in Islamic law according to the Imams of the Islamic School of Law? The research method used is qualitative with a library research type, namely a literature study that takes sources and references from readings, including books, journals, and other scientific works relevant to the discussion related to this research. The conclusion contains a new definition of GAM, whether it is included in rebellion or not.