the lawyer's business in criminal proceedings is divided into three stages. That is, the public security investigation stage, the procuratorate review and prosecution stage and the court trial stage. In these three stages, the lawyer's service contents are as follows: (1) Lawyer's service in the public security investigation stage. 1. Learn from the investigation organ about the suspected crime and the relevant situation of the case, and make comments; 2. Meet with the criminal suspect in custody, understand the case and provide legal advice and help; 3. Acting as an agent to appeal and accuse; 4. Apply for changing compulsory measures and obtaining a bail pending trial. (2) Lawyer service of the procuratorate in the stage of examination and prosecution 1. Meet the criminal suspect in custody, understand the case and provide legal advice and help; 2. Consult, extract and copy the case files; 3. Verify the relevant evidence with the criminal suspect; 4. Apply to the people's procuratorate to collect and obtain evidence; 5. With the permission of the people's procuratorate, and with the consent of the victims or their close relatives and witnesses provided by the victims, materials related to this case may be collected from them. 6. Put forward a written defense opinion that the criminal suspect is innocent, the crime is light or mitigated, and the punishment is exempted. (3) Lawyer services at the trial stage of the court 1. Meet the defendant in custody, understand the case and provide legal advice and help; 2. Consult, extract and copy the case files; 3. Verify relevant evidence with the defendant; 4. Apply to the people's court to collect and obtain evidence; 5. Investigate and collect evidence related to the case according to law; 6. Appear in court to participate in court investigations and court debates, and put forward written defense opinions on the defendant's innocence, lighter crime or mitigated punishment. 7. Listen to the defendant's opinions on the verdict and give legal help.