While competing claims underlie much of international conflict, we know surprisingly little about the extent and quality of state claims that lead to conflict. Claims such as Russia's demand over Ukrainian independence and territorial integrity, and China's expansive claims in the South China Sea, represent a particular set of maximalist claims that distinguish them from more typical interstate disagreements. Despite the attention maximalist claims receive from policymakers and analysts, we have little systematic knowledge of why some states make more extensive claims than others. Understanding this is crucial, as more extensive claims are more likely to be perceived as illegitimate by adversaries and to contribute to militarized conflict. I propose a new theory that traces the variation in the extent and quality of claims to differences in domestic political institutions. Specifically, I examine how regime type shapes state incentives and opportunities to make maximalist claims over territory and maritime zones. My analysis considers the varying levels of constraints on democratic leaders and the potential audience costs they may face, as well as the diversity within autocracies. Using an original dataset of unilateral maritime boundary claims, I show that certain types of autocracies are more prone to making excessive claims than other autocracies or democracies. This paper contributes to understanding an important source of variation in foreign policy, particularly in an era where personalistic leadership is on the rise and international constraints are weakening.