The accelerating pace of scientific development in the contemporary world has opened new horizons of technology to humankind. In this regard, judicial systems have witnessed the introduction of innovative technologies that have brought significant transformations to the judicial proceedings. These developments, although promising and potentially helpful to the Judiciary, are also accompanied by challenges, including the fact that the religious authenticity of certain such tools, such as polygraphs or lie-detection devices, is a matter of reflection. Given the importance of the discussion, the present article, through a problem-oriented research and by adopting a descriptive-analytical approach, analyzes the validity and legitimacy of polygraphs from a jurisprudential perspective. The findings of the research indicate that polygraph technology, due to its conjectural and error-prone nature, pursuant to the primary principle of the non-authoritativeness of conjecture, is confronted with challenges and the impediment of doubt regarding the reliability of its finding; and it stands in opposition to some established juristic rules and accepted principles, such as the implication of the rule of evidence (bayyinah), the principle of preferring pardon over punishment, the presumption of innocence of the accused, and the content of the principle of dignity, and therefore lacks the capacity to prove and impose its findings upon the judicial system of the country, and ultimately may be used only as an instrumental, and not independent, method in the judicial proceedings.