Legal basis: Article 192 of the Criminal Procedure Law of People's Republic of China (PRC). The public prosecutor, the party concerned, the defender or the agent ad litem have objections to the witness testimony, which has a great influence on the conviction and sentencing of the case. If the people's court deems it necessary for the witness to testify in court, the witness shall testify in court. The provisions of the preceding paragraph shall apply to the people's police who testify in court and testify about the criminal acts they witnessed while performing their duties. If the public prosecutor, the parties, the defenders and the agents ad litem have objections to the expert opinion, and the people's court deems it necessary for the expert to appear in court, the expert shall testify in court. If the appraiser refuses to testify in court after being notified by the people's court, the appraisal opinion shall not be used as the basis for finalizing the case.