The article touches upon the approach of the modern Islamic legal thought to the Islamic state andcaliphate. The author explains the fundamental principles of Islamic concept of the power (caliphate)and points out that this concept is gradually deviating from real political practice. The modern Islamiclegal doctrine stresses several aspects of the classical theory of caliphate such as nature of Islamicpower as an instrument for defense and maintaining of religion together with solving temporal issues,“ba’yat” institution which is a sort of oath for the ruler and a special treaty between him and his subjectsabout their mutual rights and duties and also the principle of consultation which is used during caliph’selection. In the middle ages, the Ottoman Empire became the successor of the Arab caliphate. Thecaliphate itself remained as a political institution till the collapse of the Ottoman Empire after the WorldWar I. The idea of the revival of caliphate was one of the demands included in the programs of someIslamic political organizations and movements during 20th century. After emergence of Islamic State ofIraq and Levant (ISIL) the caliphate converted to a specific political project. In June 2014, ISIL whichchanged its name to become “Islamic State” (IS) declared creation of caliphate. IS justified such stepby referring to some wordings of Prophet Muhammad who, as believed, predicted revival of caliphateafter a historical period when different modes of power were changing each other. IS considers its maingoal to be the complete implementation of Sharia and copying power institutions of so called righteouscaliphs. In practice, the Sharia implementation in IS leads to mass killings, forcing nonmuslims toadopt Islam, interference into internal life of Muslim states and terror attacks. The modern Islamic legalthought criticizes IS severely stressing its violence of religious postulates and Shariat provisions as faras the mode of announcing of Caliphate, “ba’yat” procedure and observance of consultation principleare concerned. This thought draws attention to the fact that IS practice doesn’t meet Sharia limits. Itconcludes that IS cannot pretend to be caliphate as well as it is not Islamic power at all. This organizationis terroristic not only according to the norms of international law and national legislation of a numberof states but Sharia provisions.