often been more concerned with ideology than traditional jurisprudence and there is no agreement among them as to what form a modern Sharia-based "Islamic state" should take. This is particularly the case for the theorists of Islamic economics and Islamic finance, who have advocated both free-market and socialist economic models. The notion of "Sharia-compliant" finance has become an active area of doctrinal innovation and its development has had a major impact on business operations around the world. Contemporary applications Muslim-majority countries The legal systems of most Muslim-majority countries can be classified as either secular or mixed. Sharia plays no role in secular legal systems. In mixed legal systems, Sharia rules are allowed to influence some national laws, which are codified and may be based on European or Indian models, and the central legislative role is played by politicians and modern jurists rather than the ulema (traditional Islamic scholars). Saudi Arabia and some other Gulf states possess what may be called classical Sharia systems, where national law is largely uncodified and formally equated with Sharia, with ulema playing a decisive role in its interpretation. Iran has adopted some features of classical Sharia systems, while also maintaining characteristics of mixed systems, like codified laws and a parliament. Constitutional law Constitutions of many Muslim-majority countries refer to Sharia as a source or the main source of law, though these references are not in themselves indicative of how much the legal system is influenced by Sharia, and whether the influence has a traditionalist or modernist character. The same constitutions usually also refer to universal principles such as democracy and human rights, leaving it up to legislators and the judiciary to work out how these norms are to be reconciled in practice. Conversely, some countries (e.g., Algeria), whose constitution does not mention Sharia, possess Sharia-based family laws. Nisrine Abiad identifies Bahrain, Iran, Pakistan, and Saudi Arabia as states with "strong constitutional consequences of Sharia "on the organization and functioning of power". Family law Except for secular systems, Muslim-majority countries possess Sharia-based laws dealing with family matters (marriage, inheritance, etc.). These laws generally reflect influence of various modern-era reforms and tend to be characterized by ambiguity, with traditional and modernist interpretations often manifesting themselves in the same country, both in legislation and court decisions. In some countries (e.g., parts of Nigeria), people can choose whether to pursue a case in a Sharia or secular court. Criminal