Depends on the circumstances. It is valid if approved by the court. A lawyer's letter is issued to the outside world in the name of a law firm. Opinions and opinions on some issues are a kind of unit behavior and need to be stamped with the seal of the law firm. Whether the lawyer's letter is valid does not depend on the authenticity of the lawyer's letter. It depends on the court's approval. Only the lawyer's letter approved by the court is valid. Article 33 of the Chinese People's Lawyers Law stipulates that lawyers, as defenders, have the right to hold a lawyer's practicing certificate, a law firm certificate and a power of attorney or a legal aid letter to meet with criminals in custody or under residential surveillance in accordance with the provisions of the Criminal Procedure Law. suspect, defendant. Defense lawyers meet with criminal suspects and defendants without residential surveillance.