First of all, the current law in our country does not clearly stipulate that an agent ad litem cannot serve as a witness at the same time.

Article 70 of the Civil Procedure Law stipulates that all units and individuals who know the case are obliged to testify in court. The person in charge of the relevant unit shall support the witness to testify. According to this clause, a witness is a person who knows the case and gives testimony. In our country, anyone who knows the case has the obligation to testify except those who are physically or mentally defective or young and cannot correctly distinguish right from wrong and express their will. Neither the current civil procedure law nor the rules of evidence explicitly prohibit agents ad litem from providing witness testimony as witnesses at the same time. Therefore, we can't directly deny the right of an agent ad litem to produce the testimony of a witness if it is not prohibited by law.

Secondly, the validity of witness testimony issued by an agent ad litem as a witness at the same time shall be exercised by the other party.

One of the basic principles of civil litigation is the principle of punishment. One of the characteristics of China's civil procedure law is that it is convenient for both parties to sue and courts to handle cases, emphasizing both fairness and efficiency. Article 72 of the Supreme People's Court's Provisions on Evidence in Civil Proceedings stipulates: "If the evidence presented by one party is insufficient to refute, the people's court may confirm its probative force." This provision clarifies the right of civil litigants to dispose of the validity of evidence. As far as this case is concerned, although Li did not testify as a witness in court, if the defendant Liu explicitly agreed with Li Li's witness testimony and did not raise any objection, the court may determine the evidence according to the punishment imposed on the parties. Of course, once Liu denies that the witness is also the agent of this case and has an interest in this case, or denies it on the grounds that the witness did not testify in court, the court should adopt his objection.

Finally, some people may think that the basic obligation of witnesses is to testify in court and not to attend the trial. As an agent ad litem, Li Li has participated in the trial, which is tantamount to sitting in on the trial process and should not appear as a witness. The author believes that Article 69 of the Supreme People's Court's Several Provisions on Evidence in Civil Proceedings stipulates that the following evidence cannot be used as the basis for determining the facts of a case alone: (1) the testimony made by minors that is not commensurate with their age and intellectual status; (2) Testimony issued by a witness who has an interest in the party concerned or his agent; (3) audio-visual materials with doubts; (four) copies and reproductions that cannot be checked with the original and the original; (5) Testimony of witnesses who fail to testify in court without justifiable reasons. Judging from this provision, the law does not directly deny the evidential effect of this kind of evidence itself, but gives a detailed explanation of "orphan evidence". Li Li, the plaintiff, can choose to provide Li Li's witness testimony by the way that the witness does not appear in court. As for the validity of the evidence, the defendant will exercise the right of cross-examination, which is reasonable whether the court finds out the facts or the parties independently dispose of the litigation rights.