Legal analysis: 1. The law firm signs an entrustment agreement with the client in duplicate, one for the client and one for the law firm to file; 2. The power of attorney signed by the client is in triplicate, one for the case-handling organ, one for the contractor's file and one for the client's retention; Criminal entrustment III. A letter of introduction from a law firm, which shall be submitted by the lawyer to the case-handling organ. For the parties who need to provide legal aid, the law firm may entrust a lawyer to undertake it, but it shall go through the entrustment procedures in accordance with the regulations.
Legal basis: Civil Code of People's Republic of China (PRC).
Article 919 An entrustment contract is a contract in which the principal and the agent agree that the agent shall handle the principal's affairs.
Article 922 The agent shall handle the entrusted affairs in accordance with the instructions of the principal. If it is necessary to change the client's instructions, it shall be approved by the client; If it is difficult to get in touch with the client due to an emergency, the agent shall properly handle the entrusted affairs, but shall report the situation to the client in time afterwards.