Law is a set of institutional statements that oblige, prohibit, or authorize actions for actors in different situations. Understanding these language-based institutional statements will help to better understand processes and design more efficient policies. However, the linguistic complexities contained in the text of these propositions have made it difficult to process them. In order to overcome these problems, this paper presents a systematic way of processing rules in Persian language based on institutional grammar tool. Institutional grammar tool uses a general syntactic structure, including the five components: “attributes”, “deontic”, “aim”, “conditions”, and “or else”. “Attribute” is any kind of value that separates the actors subject to the institutional statement from other actors. “Deontic” expresses possible (permitted), must (obligatory), and must not (forbidden) meanings. “Aim” describes the action and consequence that the deontic component is concerned with. “Conditions” refer to variables that specify the time and place that an action is permitted, obligatory, or forbidden. “Or else” relates to the consequence of non-compliance. The most important component that should be considered more due to the characteristics of Persian language as the contextual language of this research is the “Deontic” component. In this regard, by examining the literature and studying the existing laws, the examples of expressing the deontic component in Persian language in the form of modal verbs, linking sentences and declarative sentences are identified and classified according to the different types of deontic. Finally, the proposed systematic method is used for analysing the law on preventing and combating fraud in carrying out scientific works. The results of this analysis indicate some shortcomings in this law. For example, some of the main actors who can contribute to the process of preventing fraud in scientific works have been neglected. The “or else” component has not been explicitly stated in many statements which may decrease the effectiveness of these statements as they may be treated as a norm, which are not obligatory, instead of rules. The results of this analysis led to a better understanding of the law and the identification of its shortcomings, which could be used for further corrections.