Positionand acceptance on fatwa of Council of Indonesian Ulama (MUI) in Indonesian legal system are questioned again. Generally fatwa is considered as unforcefull legal interpretations which cannot be equated with a court decision or qanun (the acts). On Indonesian legal system, MUI and its fatwa position in Indonesia are complex enough to be classified. On one side, MUI is not a state organ and the productsare not legally binding, but on the other side, both of them influence State and Muslim citizens legally, socially and politically. The acceptance of the fatwa by government, either fatwa of Sharia National Board or Fatwa Commission, is also depend on what State regulated in theActs. It can be influenced by directindirect legitimation of MUI, and it affects whether adopting fatwa fully or its principle only in the formal laws. Regarding the acceptance and the position of fatwa in religious court, it is concerned on the Islamic finance dispute settlement cases. Related to the issue, although fatwa is the sole resource of Islamic transaction and there is a Compilation of Sharia Economic Law legalized and adopted mostly from the fatwas, but the used is quiet invisible, especially utilizing fatwa on ‘unlawful act’, particularly claim of ‘it is against sharia principles’ as its reason of case (fundamentumpetendi).