By recognizing the inherent duality of private law and public law, each domain has been allocated its distinct territory. Despite the relative and interconnected nature of these realms, the application of public law within its designated territory is essential due to its specific role, functions, and methodologies. Throughout history, fundamental rights (public laws) have governed the relationship between the government and its citizens, while private rights (civil laws) have governed the interactions between individuals. This demarcation of territories is not exclusive to Iran; numerous countries worldwide have embraced this division, leading to significant substantive and procedural implications.Notably, in recent years, Iran has witnessed a notable expansion of the public law domain within its legal system, which has raised concerns about its extent. This expansion can be attributed to several underlying reasons. One primary factor is the inadequacy and limitations of existing private law regulations in resolving societal issues. Consequently, legislators are compelled to address private law matters by formulating solutions based on public law principles, inadvertently diverting the core problem into the realm of public law. This practice, however, fails to address the root causes and restricts the available solutions to those provided by public law. As a result, the practical scope of public law expands beyond its intended boundaries. The excessive and multifaceted growth of public law can have far-reaching detrimental effects.Thus, the central question emerges: What potential harm can the development of public law inflict on citizens' rights, and what are the driving forces behind this expansion in Iran? This research posits that the government's inclination towards exercising authority, excessive interventions in social and economic matters, undervaluing of liberal principles, a tendency to resort to public law in ambiguous cases, and the adaptable nature of public law methods are among the contributing factors to the widening scope of public law. Moreover, the duality of influences on Iran's public law system—Western legal traditions and Shia jurisprudence—has led to its distinct development. Some facets of Iran's public law draw inspiration from Western legal systems, while others find their origins in Shia legal doctrines.It is worth noting that Iran's legal system is bound by Article 4 of the Constitution, which mandates the utilization of Sharia rulings and adherence to Islamic standards in all laws and regulations. This requirement, however, diverges from Western legal systems where such a mandate is not observed.The realm of public law has undergone extensive development, permeating even the most intimate legal issues. Notable examples of this expansion include the broadening of public law in labor law, characterized by significant government interventions in the field. Similarly, the realm of public law has made significant strides in business law, and its influence has extended to matters concerning property rights. The objective of this research is to contribute to the advancement of public law in Iran by conducting a comprehensive analysis of its benefits and drawbacks through a systematic examination of its expansion.To fulfill this objective, we delve into the causes and factors behind the development of the public law realm, providing noteworthy examples that illustrate its expansion. The research findings establish the undeniable separation of the realms of private and public rights, despite ongoing debates regarding their differentiation. In practice, even legal systems that advocate for the unity of public and private law demonstrate a distinct educational system for public law. By acknowledging the distinction between public law and private law, while acknowledging the inherent difficulty in delineating these realms in certain cases, each legal field can be allocated its designated sphere.In recent years, there has been a notable surge in the expansion and growth of the public law realm. Numerous issues that were traditionally and conventionally within the purview of private law have now either entirely or to a significant extent fallen under the domain of public law.