Research On The Litigation Guarantee Mechanism Of The Criminal Expert Opinion's Credibility

In the criminal proceedings, appraisers provide a scientific, impartial and professional expert opinion, in the court hearing, the expert opinion applied to conviction and sentencing correctly, and the public's view of expert opinion's scientific reliability is a high evaluation and generally recognition. In this case, we can say the criminal expert opinions gain credibility. However, in the practice of judicial identification, the public's trust and respect of expert opinions reduced greatly. The main cause of the repeated identification and the complaints of identification is public's distrust of the litigation procedure, but not only or mainly due to the errors or falsities of expert opinions.The reasons for the reduction of the criminal expert opinions' credibility can be divided into two levels. One is the factors in the formation process of the expert opinion: the institution and experts of the appraisal are difficult to be neutral, affecting the impartiality of the expert opinion, the start and implementation of the appraisal are totally closed to the defense, the science and technology bases of the appraisal are limited. Another is the factors in the process of criminal procedure: the defense's right to read case record can not be ensured, the expert opinion can not be fully cross-examined, and the judge abuses the judicial discretion. This factors work together to reduce the credibility of the expert opinion.In addition to strengthening the quality control in the generation process of the expert opinion, the expert opinion's credibility can also be enhanced by perfecting the litigation guarantee mechanism. Specifically, namely, to refine the expert opinions discovery rules, to perfect the relevant system of court testimony, to regulate the procedure and contents of trial inquiry, to perfect the expert assistant system and regulate the discretion of judges.Expert opinions discovery system is the premise to ensure the defense participating in cross-examination effectively. In the current “Criminal Procedure Law”, only simply stipulate the inform procedure and the reading-file system, but the expert opinion discovery system can not be found. In practice, the defense can just gain the final expert opinion and can't review the test data or pictures of identification. So, it is necessary to perfect the procedure and contents of the expert opinion discovery system.The cross-examination is the important part to identify the evidence ability and the weight of evidence value. In the cross-examination, the defense enjoys the right to ask appraiser face to face, so that the defense can apply for appraiser to appear in the court, and ask him questions related to identification. Therefore, we should perfect the system of appraiser testifying in court, and regulate the procedures and contents of the courtroom inquiry. Because the expert opinion is professional and scientific, in the cross-examination proceeding, the defense has the right to obtain expert assistant.The judge is the final gatekeeper to evaluate the probative value of the expert opinion, the discretion power should be standardized. As for the evidence ability of the expert opinion, the judge should evaluate the form of it according to the laws and judicial interpretations, besides, strengthen the review of the expert opinion's scientific reliability. Meanwhile, the judge should public the reason to adopt the expert opinion, so that the credibility of expert opinion can be enhanced.