Attorney-client privilege is a legal concept that protects communications between a client an his or her attorney and keeps those communications confidential. This privilege encourages open and honest communication between clients and attorneys, and is considered as one of the strongest privileges available under law. However, in the United States, not all state courts treat attorney communications as privileged. For instance, Washington state law, and the federal courts when applying federal law, only protect client communications—an attorney's communication will only be protected as privileged to the extent it contains or reveals the client's communications. In contrast, California state law protects the attorney's confidential communications regardless of whether they contain, refer to or reveal the client's communications. In addition, the United States Supreme Court has ruled that the privilege generally does not terminate upon the client's death. See Swidler & Berlin v. United States.