If it is an administrative case, the Administrative Reconsideration Law stipulates: "The applicant and the third party may consult the written reply, evidence, basis and other relevant materials of the specific administrative act made by the respondent, and the administrative reconsideration organ shall not refuse it except those involving state secrets, commercial secrets or personal privacy." In other words, if you are dissatisfied with a specific administrative act, you can go to the reconsideration organ to consult the relevant materials after applying for administrative reconsideration, and of course you can also entrust a lawyer to consult it. The Administrative Punishment Law does not stipulate that the parties or lawyers can consult the materials during the investigation stage of administrative cases, so it is right for the police station to refuse lawyers to consult the materials.
If you want to consult the case materials as evidence in civil litigation, you can apply to the court to collect evidence at the police station. In reality, lawyers or other agents have obtained materials from the police station to provoke the relationship between the parties or between the parties and witnesses, so it is necessary for the police station to act cautiously.