Legal basis: Article 35 of the Lawyers Law of People's Republic of China (PRC) may apply to the people's procuratorate or the people's court for collecting and obtaining evidence or to the people's court for notifying witnesses to testify in court according to the needs of the case; If a lawyer investigates and collects evidence by himself, he may, with the lawyer's practice certificate and the certificate of the law firm, investigate the situation related to undertaking legal affairs with the relevant units or individuals.