It is a common practice for outside litigation counsel to represent current, and even former, employees of corporate clients during depositions. This practice, however, is governed by ethical rules (and opinions and case law) that must be considered in advance.
There are two major exceptions to the lawyer-client privilege under the California Evidence Code, as discussed below. 2.1. Crime or fraud. 2.2. Preventing death or substantial physical harm.
The United States Supreme Court rejected the control group test in Upjohn v. United States, 449 U.S. 383 (1981). Most courts now apply the Supreme Court's reasoning in that case to corporate privilege claims, including those involving former employees.
Therefore, as with any third-party witness, discussions with former employees are not automatically treated as privileged or confidential in litigation (though the attorney's notes and other work product may be another story). But there are some important exceptions to this general rule.
The so-called Upjohn warning takes its name from the seminal Supreme Court case Upjohn Co. v. United States,1 in which the court held that communications between company counsel and employees of the company are privileged, but the privilege is owned by the company and not the individual employee.
The protections of the attorney-client privilege survive indefinitely. This means that the protections remain in place even when the attorney-client relationship ends, no matter if the relationship ends due to voluntary termination or due to the death of one of the parties.
Since the client, and not the attorney, holds the privilege, the client holds the ultimate authority to assert it or waive it.