Muhakkima (Arabic محكمة) was one of the earliest groups to form within the Kharijite movement. The name of the movement is derived from its opposition to arbitration as a means to determine a successor, on the grounds that "judgement belongs to Allah alone (lā ḥukma Illā li-llah)."
The Muhakkima were those early opponents of the Caliph Ali ibn Abi Talib. Among the movement's leaders was Abdullah ibn Wahb al-Rasibi. They were defeated at the Battle of Nahrawan.
Muhakkima and Ibadi Islam
Ibadi Islam is the only extant group which claims to have originated in the Muhakkima movement.
References
Muhakkima Wikipedia(Text) CC BY-SA