Article 35 of the Lawyers Law of the People's Republic of China stipulates that an entrusted lawyer may apply to the people's procuratorate or the people's court to collect and obtain evidence or to the people's court to notify witnesses to testify in court according to the needs of the case. Lawyers who investigate and collect evidence on their own can undertake legal affairs to the relevant units or individuals under investigation with the lawyer's practice certificate and the certificate of the law firm.