If you are referring to a criminal case, according to the provisions of the Criminal Procedure Law, lawyers are not allowed to consult the investigation files in the investigation of criminal cases, but they can learn about the alleged crimes, meetings and correspondence, application for bail pending trial, and representation of charges and complaints. The people's procuratorate may consult, extract and copy the litigation documents and technical appraisal materials of the case from the date of examining and prosecuting the case, and may meet and correspond with the criminal suspect in custody. Since the people's court accepted the case, the defense lawyer can consult, extract and copy the materials of the alleged criminal facts in this case, and can meet and correspond with the defendant in custody.
In the investigation of public security organs, it is impossible to find the parties and witnesses to re-investigate and collect evidence. However, in the examination and prosecution, defense lawyers may, with their consent, collect materials related to the case from witnesses or other relevant units and individuals, or apply to the people's procuratorate or people's court to collect and obtain evidence, or apply to the people's court to notify witnesses to testify in court.