The use of a polygraph (lie detector) in criminal cases is a novel matter, raising questions about the position of the polygraph (lie detector) in criminal case evidence. This research discusses the regulation of polygraph (lie detector) use as evidence in criminal law outside the Criminal Procedure Code (KUHAP). The study employs a normative research method to systematically explain the status of the lie detector as indirect evidence in criminal law proceedings in Indonesia. The findings indicate that, based on Article 184 paragraph (1) of the Criminal Procedure Code, the provisions regarding the use of a polygraph (lie detector) as legitimate evidence are not explicitly regulated, considering that the polygraph (lie detector) is not primary evidence in court. The printed results of a lie detector examination can be classified as an expert opinion. Thus, a lie detector examination cannot stand alone and requires expert knowledge to be considered valid evidence in court proceedings.