In the legal system of Iran and America, the issue of confidentiality of client information before the lawyer has been emphasized in different ways, and the legislators of both systems have tried to protect the clients in a legal structure. In Iran's legal system, keeping the client's information with the lawyer has a long history, and the preservation of the secrets of individuals has been given complete coherence in the jurisprudence rules, which are the origin of the laws of the Iranian legal system. In the American legal system, the protection of the client's secrets with the support of the common law system has a proper coherence. With this definition, the issue of confidentiality of client information in the American legal system has a wider scope and components than the Iranian law, which can be taken into consideration by the Iranian legal system. The results show that the issue of the permanence of the client's information in the eyes of the lawyer and the responsibility for it has been one of the concerns of the legislator, who has tried to oblige the lawyers to protect the secrets of the clients, the two countries. Unless, as per the necessity and the will of the law, unauthorized disclosure of secrets is done by the lawyer, which of course is much more limited in the American legal system than in the Iranian legal system.