Through a close examination of British policy toward native legal institutions in colonial Sudan, I argue that many theorists of the modern state [Scott 1998; Tilly 1990; Mitchell 1991] have made a fundamental mistake about how states behave. These theorists claim that the state, colonial or otherwise, is primarily interested in rendering the law “legible” – that is to say, predictable, calculable, and easily replicated across time and territory. Indeed, this “standardization” (and often outright codification) of the law is generally regarded as one of the hallmarks of state formation and constitutive of the very definition of what it means to qualify as one. [Messick 1996; Spruyt 1994] This paper challenges those assumptions and shows their limitations in the colonial context. Drawing primarily from the case of early 20th century Sudan, it shows that under certain conditions, a regime will intentionally create a realm of “legal ambiguity” in which the behavior of the law becomes impossible for even the state to predict. In such situations, the state actively encourages non-state actors to behave in “illegible” ways. This conclusion is reached through a close study of British policy toward Ali al-Tom, chief of the Kabbabish Arabs and a linchpin of colonial policy in central Sudan throughout the 1920s and 1930s. As in many of their other colonies, British colonial administrators adopted a policy of formalizing and standardizing the legal powers of Sudan’s judicial institutions and actors. Yet curiously, Ali al-Tom was exempted from this countrywide policy – indeed, colonial administrators actually lobbied aggressively for his legal powers to remain as uncodified and unpredictable as possible. As a result, the course of law in al-Tom’s jurisdiction was, for the British, essentially “illegible.” To properly explain why al-Tom’s authority was allowed to remain ambiguous when that of all others was standardized, I employ Carl Schmitt’s concept of “exceptionality,” as well as the vast literature on “states of emergency” – situations in which the normal rule of law is suddenly suspended. [Wedeen 2008; Honig 2009] When read alongside the larger body of scholarship on British policies in Sudan, it becomes clear that colonial officers were unwilling to explicitly define al-Tom’s legal powers for the simple reason that doing so would have constrained his ability to respond to unexpected threats to British rule. This tension between colonial hegemony and colonial knowledge, usually thought to be closely intertwined, marks an important critique of how most theorists claim states behave.