Introduction
The constitution, by establishing the fundamental structural and procedural principles of government, defines the supreme law of a given polity (Boudreaux & Pritchard, 1993:11). Every theory of constitutionalism presupposes that a constitution must be capable of functioning over a relatively long period of time. The notion of constitutional endurance is closely intertwined with key normative issues such as constitutional amendment. The very idea of constitutional amendment arises from the premise that no generation possesses the exclusive wisdom to bind future generations irreversibly or to design a constitution immune from failure. Consequently, there exists an inherent right to amend the constitution to remedy its deficiencies and to strengthen its principles when necessary (Hatchard, 2004:44–45). 
Amendment provisions, as one of the essential pillars of constitutionalism, enable the constitutional text to evolve gradually, addressing the shortcomings of its initial design and responding to emerging challenges within the constitutional order (Albert, 2015: 656). The primary means of revising a constitution is the formal procedure explicitly set forth within the document itself. The more fundamental the proposed changes, the more essential recourse to formal procedures becomes (Assefa, 2012:103). 
However, formal amendment rules often render constitutional change exceedingly difficult, and experience demonstrates that the politics of constitutional revision are highly contentious. Accordingly, most scholars acknowledge that constitutional change is not achieved exclusively through formal amendment procedures; in some instances, it occurs informally (Anderson, 2008: 59). Where the formal path to amendment proves arduous or obstructed, alternative routes become available to political actors to achieve its practical equivalent (Albert, 2014: 1062). 
It may thus be argued that informal amendment practices play a significant role in reconstructing the constitution and reshaping its meaning in response to subsequent developments. The most accurate account of a constitution’s evolution must therefore consider not only formal amendments but also informal transformations. Only through this dual lens can one attain a deeper understanding of a state’s constitutionalism (Besso, 2005:84). 
Recognizing the importance of informal constitutional change within the field of constitutional law, this paper explores the concept of constitutional amendment to clarify the nature, foundations, and legitimacy of informal constitutional transformation. Particular attention is devoted to the process of constitutional interpretation as a mechanism capable of functioning as a form of informal amendment. The central question addressed in this study is: despite the explicit provisions governing formal amendment in written constitutions, what are the functions and implications of informal amendment and constitutional interpretation? To answer this question, the paper adopts a descriptive–analytical approach—first examining the concept and dimensions of constitutional amendment, and then analyzing the interpretive role of the official constitutional interpreter and the processes through which informal constitutional change occurs. 
Literature Review
Although several distinguished Iranian scholars—such as Habibzadeh and Mansourian, in their article “An Analysis of Constitutional Change Beyond the Formal Amendment Procedures Prescribed Therein,” and Morad Khani, in “Informal Constitutional Change: Foundations, Instances, and Approaches”—have addressed the possibility of constitutional change through means other than the formal amendment process enshrined in the constitutional text, the crucial role of constitutional interpretation in facilitating such informal change has not yet been seriously examined within domestic scholarship.
Research Objective
The present research seeks to understand the importance of discussions on informal constitutional change in constitutional law. It aims to examine real, yet unwritten, changes to the constitution—particularly those arising from the interpretation process, which bypasses the formal amendment procedure and cannot be justified through it—and to clarify the basis for the legitimacy of such changes.
Methodology
This research, by studying various domestic and international books and articles, has collected materials through library research and note-taking. It examines the subject using a descriptive-analytical method.
Findings and Conclusion
Although the formal amendment mechanism is a vital necessity for constitutional reform, the role of informal procedures in changing the constitution's content is so significant that they may even render formal amendment procedures irrelevant in determining the constitution's actual content. Dynamic interpretation, as a common method of adapting the constitution to contemporary developments, without formal stages or changes to the text, reveals hidden sub-textual and pre-textual layers not visible in the written document itself. This leads to informal change and amendment of the constitution. Consequently, the interpreting authority plays a crucial role in constitutionalizing procedures and institutions outside the constitution that have been created by the political branches. Interpretation is one of the informal methods of constitutional amendment, through which the interpreter links the written constitutional text to its unwritten layers. In this process, it is inevitably influenced by political practices and attempts to harmonize the text with the political realities of society. Political practices, by being reflected in the opinions and interpretations of the interpreting authority, take on a legal color and appear more justified.
In the Iranian constitutional system, the Guardian Council, with the aim of ascertaining the legislator's intent and discovering the essence of the constitution, introduces unwritten aspects of the constitutional principles that are not encompassed by the explicit text. Thus, through its official interpretations and without changing the written document, this authority, by unveiling the unwritten layers of the constitution, has paved the way for its change outside the formal process stipulated in Article 177 of the constitution—that is, informally. Since, in our constitutional system, interpretation is tantamount to the constitution and holds an effect and status similar to that of the written constitutional text, the interpreting authority, by granting constitutional status to an unwritten principle or practice without engaging in the difficulties of the formal amendment process, brings about informal constitutional change through the gateway of interpretation. Given the constitutional binding nature of interpretation in the Iranian constitution, these changes become part of the constitutional system and are treated as valid and binding.
Although changes that are the unconscious product of the constitution's dynamic system and subsequently gain the approval of political actors and the people can be considered valid, changes that are carried out by circumventing the difficult legal procedures call into question the wisdom of the original constitution-maker in dedicating a specific article to revision—aimed at preventing its arbitrary application and preserving the constitution's stability. Therefore, it is essential to distinguish organic interpretations, which arise from the complex interaction of forces among the different political branches of the government, from unreasonable interpretations that, by granting extra-legal and unlimited authority to certain institutions, disrupt the system of checks and balances and seriously conflict with the purpose of the text. Any change to the constitution must be labeled as legitimate and legal only after cautious and meticulous scrutiny, so that while allowing for the logical evolution of the constitution and its adaptation to conditions and the times, the endurance and integrity of the law are not undermined, and the path for any misuse is blocked.
Thus, although the amendment process serves an important practical purpose—namely, changing the constitutional text whose errors have been revealed over time and through experience—the prevalence of informal amendments may, in the future, nullify their usefulness. Furthermore, it is essential that the aspects of change in the constitutional system are considered sufficiently important and fundamental to determine the true scope of the constitution. Therefore, such a phenomenon must be approached with caution.