在刑事實務上，警方經常以誘捕偵查的手法查緝色情行業，究竟色情業者何時成立促成性交易罪，誘捕警員之供述得否作為認定犯罪之唯一證據，成為最近一則臺灣高等法院判決之焦點。該判決延續最高法院的立場認為，促成性交易罪之「以營利」要素係指行為人以追求外部關係之財產利益為目的，誘捕警員之供述應適用超法規補強法則，不得作為有罪判決之唯一證據。本文將指出，促成性交易罪應以保護性工作者之自由為目的，行為人僅在其促成行為具有剝削作用時成立本罪；至於最高法院發展之超法規補強法則，不僅欠缺類推適用之前提，其適用之可疑證言類型亦係出於恣意，係違法之司法續造，不應將其擴大適用於警員之供述。

In practice, the police often use the entrapment technique to investigate sex industry. Whether it is proper to determine the time of the offense of pandering based solely on the testimonies of the police officer who conducts the entrapment, is discussed in the recent case of Taiwan High Court. This case follows the opinion of the Supreme Court that the meaning of “to gain” element in crime of pandering should be narrowed to “acquire interests from external relations”. Besides, the testimony of the police officer who conducts the entrapment should apply to the extralegal rule of corroboration, and shall not be used as the sole basis of conviction. This article suggests that the purpose of the crime of pandering is to protect the freedom of the sex workers, and therefore the crime is established only when exploitation effect exists. As to the extralegal rule of corroboration, there is no premise required for the use of analogy. Also, the determination of types of doubtful testimonies that the extralegal corroboration rule applies is arbitrary. This article suggests that the law-making by judge at issue is illegal and should not be further applied to the testimonies of police officers.