The Ottoman Empire was governed by different sets of laws during its existence. The Qanun, sultanic law, co-existed with religious law (mainly the Hanafi school of Islamic jurisprudence). Legal administration in the Ottoman Empire was part of a larger scheme of balancing central and local authority. Ottoman power revolved crucially around the administration of the rights to land, which gave a space for the local authority develop the needs of the local millet. The jurisdictional complexity of the Ottoman Empire was aimed to permit the integration of culturally and religiously different groups. The Ottoman system had three court systems: one for Muslims, one for non-Muslims, involving appointed Jews and Christians ruling over their respective religious communities, and the "trade court". The codified administrative law was known as kanun and the ulema were permitted to invalidate secular provisions that contradicted the religious laws. In practice, however, the ulema rarely contradicted the Kanuns of the Sultan. These court categories were not, however, wholly exclusive: for instance, the Islamic courts—which were the Empire's primary courts—could also be used to settle a trade conflict or disputes between litigants of differing religions, and Jews and Christians often went to them to obtain a more forceful ruling on an issue. The Ottoman state tended not to interfere with non-Muslim religious law systems, despite legally having a voice to do so through local governors. The Ottoman Islamic legal system was set up differently from traditional European courts. Presiding over Islamic courts would be a Qadi, or judge. However, the Ottoman court system lacked an appellate structure, leading to jurisdictional case strategies where plaintiffs could take their disputes from one court system to another until they achieved a ruling that was in their favor. Throughout the 19th century, the Ottoman Empire adhered to the use of three different codes of criminal law.