Legal basis: Criminal Procedure Law of People's Republic of China (PRC).
Article 61 The testimony of a witness must be cross-examined and verified by the public prosecutor, the victim, the defendant and the defender in court before it can be used as the basis for finalizing the case. If the court finds that a witness intentionally perjures or conceals criminal evidence, it shall deal with it according to law.
Article 62 Anyone who knows the circumstances of a case has the obligation to testify. A person who is physically and mentally defective or young, can't distinguish right from wrong and can't express correctly, can't be a witness.