Legal basis: Article 35 of the Lawyers Law of the People's Republic of China. According to the needs of the case, the entrusted lawyer may apply to the People's Procuratorate or the People's Court to collect and obtain evidence, or apply to the People's Court to notify witnesses to appear in court to testify. If a lawyer investigates and collects evidence on his own, he may use his lawyer's practicing certificate and law firm certificate to investigate the situation related to the undertaking of legal affairs to the relevant unit or individual.