The Evolution of the Concept of Oath in the System of Judicial Proof: From Sharia Foundations to Its Legal Function in Iranian Judicial Proceedings

Abstract

Oath is one of the traditional means of proof in the Iranian legal system, rooted in Imami jurisprudence and Islamic legal principles, and it has gradually evolved from a primarily moral and religious commitment into a formal evidentiary mechanism with specific legal consequences in judicial proceedings. This study aims to analyze the evolution of the concept of oath, explain its jurisprudential and legal foundations, and evaluate its position and function within the contemporary Iranian system of judicial proof. The research adopts a descriptive-analytical method based on the examination of jurisprudential sources, statutory rules, and the legal framework governing evidence in Iranian law. The findings indicate that, within the traditional structure of proof, oath was mainly employed where direct evidence was absent or insufficient and functioned as a mechanism for resolving evidentiary deadlock. Following its incorporation into positive law, however, its conditions of application, subject-matter scope, types, and legal effects became increasingly regulated. The distinction among decisive oath, supplementary oath, and presumptive oath demonstrates the diversity of functions assigned to this institution in judicial proceedings. At the same time, the development of objective and digital evidence, the expansion of documentary proof, and the changing role of judges in evaluating evidence have raised important questions regarding the continued broad reliance on oath. Excessive dependence on oath may conflict with contemporary requirements of fact-finding, evidentiary verifiability, procedural fairness, and judicial transparency. The study concludes that the continued recognition of oath in Iranian law remains defensible, provided that its use is confined to circumstances in which sufficient objective evidence is unavailable, the consequences of refusal and referral are clearly explained to litigants, and its relationship with other forms of proof is redefined in a manner consistent with modern standards of fair adjudication and evidentiary reliability.