Chapter 2 discusses the systems of government and the distribution of powers under post-2011 Arab constitutions. It first examines the issue of the overconcentration of authority in the hands of the head of state (with the notable exception of the 2014 Tunisian Constitution, which provided for a genuine semi-presidential system and a fairly robust system of checks and balances [at least on paper]). A special focus is placed on the emergency regimes: Despite some attempts to prevent abuses, the new constitutional provisions governing states of emergency continue to grant the executive branch a significant degree of discretionary power. Furthermore, the chapter shows that not only horizontal but also vertical separation of powers has remained weak. The last part of the chapter discusses the main reasons for the overconcentration of power, namely the constitutional tradition, the patriarchal family, the “top-down” constitution-making processes, and external influences. One of the major consequences of the overconcentration of authority was to undermine the principle of popular sovereignty.