Adopting Term Limits for Prime Ministers in Parliamentary Regimes: Importing a Presidential Safeguard or Reinforcing Presidentialization?

Presidential term limits are a defining feature of presidential and semi-presidential systems, where they are widely regarded as a necessary safeguard against excessive concentration of power. In parliamentary democracies, by contrast, heads of the executive are rarely subject to formal term limits. Prime ministers may remain in office indefinitely as long as they retain parliamentary confidence and enjoy their parties’ support. Against this institutional background, proposals to introduce term limits for prime ministers constitute a rare and conceptually puzzling reform: the importation of a presidential mechanism into a parliamentary system. This paper examines the implications of such reforms and asks whether prime-ministerial term limits can serve as a safeguard against democratic backsliding or should instead be regarded as a paradoxical reinforcement of presidentialization within parliamentary frameworks and dynamics. The analysis draws on the literature on the presidentialization of parliamentary democracies, highlighting the concentration of power in the hands of prime ministers, the personalization of electoral competition, and the weakening of collegial cabinet governance. These dynamics are examined alongside scholarship on executive aggrandizement, which conceptualizes democratic erosion as a gradual expansion of executive power that weakens horizontal accountability. The convergence of presidentialization dynamics and the absence of constraints on executive tenure in parliamentary systems may increase the risk of democratic backsliding. From this perspective, proposals to impose term limits embody competing institutional logics. On the one hand, they resemble a presidential-style constraint: by fixing an upper bound on executive tenure, term limits shorten time horizons, disrupt incumbency advantages, foster leadership renewal, and may limit opportunities for power accumulation, corruption, and institutional capture. On the other hand, term limits may introduce familiar presidential pathologies into parliamentary systems, including “lame-duck” dynamics, weakened electoral accountability, and incentives to govern with an eye toward post-tenure strategies rather than parliamentary confidence. Yet, an original dataset covering 29 OECD parliamentary democracies since World War II shows that exceptionally long prime-ministerial tenures are rare. Fewer than 10 percent of consecutive tenures exceeded eight years, and fewer than 3 percent surpassed twelve years. These patterns suggest that proposals to impose term limits are not responses to a widespread problem of executive overstay but rather attempts to address exceptional cases in which prolonged incumbency coincides with democratic backsliding. In this sense, term limits may function as a potential “emergency brake.” A central contribution of the paper is the development of a typology of possible prime-ministerial term-limit models, informed by practices in presidential and semi-presidential systems. This includes absolute caps on years in office, limits on consecutive terms, cooling-off periods, alternative rules defining what counts as service, and prospective versus retroactive application. Although these models vary in rigidity, they all introduce a fixed-exit logic that is structurally foreign to parliamentarism and may further personalize executive office. The paper concludes that prime-ministerial term limits are neither a panacea against democratic backsliding nor a neutral institutional mechanism. Rather, they reflect—and may intensify—presidentialized dynamics within parliamentary democracies, with potentially paradoxical consequences for executive power and democratic accountability.