刑事警察在英美法系国家普遍可以作为控方证人出庭作证,而大陆法系传统理论一般认为证人是专指向司法机关陈述所知案件情况且不具有其他诉讼身份的人员,因而主张主办案件的法官、检察官及协助其侦查犯罪的警察不得同时为证人。我国基本秉承了大陆法系关于证人的界定,所以普遍的观点是将证人和当事人、鉴定人、公安司法人员区别开来。现有不少学者对此提出质疑。那么,在我国司法实践中警察究竟应否出庭作证,警察出庭作证存在哪些障碍,警察作证制度应如何构建呢? Criminal police in the common law countries can generally appear as witnesses to the prosecution witness, while the traditional theory of civil law tradition is generally regarded as a witness refers to the judiciary to state the case is known and does not have other legal status of the persons who advocate the judge in charge of the case Prosecutors and police officers assisting them in detecting crimes may not both be witnesses. Our country basically upholds the definition of witness in the civil law system, so the common view is to distinguish witnesses from parties, appraisers and public security officials. Many scholars have questioned this. So, in our judicial practice, whether the police should testify in court, what obstacles exist when the police testify in court, and how should the police testify system be constructed?