From What Went Wrong? Western Impact and Middle Eastern Response by Bernard Lewis
Westerners have become accustomed to think of good and bad government in terms of tyranny versus liberty. In Middle-Eastern usage, liberty or freedom was a legal not a political term. It meant one who was not a slave, and unlike the West, Muslims did not use slavery and freedom as political metaphors. For traditional Muslims, the converse of tyranny was not liberty but justice. Justice in this context meant essentially two things, that the ruler was there by right and not by usurpation, and that he governed according to God's law, or at least according to recognizable moral and legal principles.