Attorney work product is the work that an attorney performs, other than communication with the client. Notes that the attorney prepares from a client interview would be related to the client communication and would be protected by the attorney–client privilege. An independent investigation that the attorney carries out for the client would not be a communication, but would be work product. The U.S. Supreme Court found that there would be privilege if the communications were sought or given in “anticipation of litigation,” a term of art from a key case establishing the bounds of privilege for attorneys conducting an investigation of corporate behavior. [ Upjohn Co. v. United States, 449 U.S. 383 (1981).] Anticipation of litigation is a broad umbrella. The threat of litigation need only be potential, not imminent. For example, a severe medication reaction would carry the potential of litigation. An investigation of a medication error could satisfy the criterion of anticipation of litigation. If the attorney directs the investigation, the information that is communicated to the attorney would be privileged, if it is not otherwise available to others.

The key distinction between attorney–client privilege and attorney work product involves whether the document in question contains information obtained from the client. The reason for making this distinction is that information protected by the attorney–client privilege is (almost) never available to discovery. Attorney work product is available, however, if the opposing party can show that justice would be denied if the work product was unavailable. For example, if an attorney made detailed summaries of important documents that then disappeared, the opposing counsel would be denied information about the contents of the documents if the work product was not available. In practice, the distinction between attorney work product and attorney–client communications is rarely of issue, judges tending to protect both equally.