What materials should be submitted when meeting the parties in a criminal case?

To meet the parties to a criminal case, you need to submit the following materials: 1, lawyer's practice certificate (original and photocopy); 2. Certificate of law firm (special letter of introduction issued by law firm to meet with criminal suspects and defendants); 3. Power of attorney for criminal defense (if it is legal aid, a letter of legal aid is required); 4. The party concerned is usually the family member of the party concerned) ID card and proof of kinship.