Everyone agrees that the client owns the attorney-client privilege. However, as an agent with both actual and apparent authority, lawyers trusted with privileged communications generally are deemed capable of waiving the client’s privilege.
However, in Harold Sampson Children’s Trust v. Linda Gale Sampson 1979 Trust, 679 N.W.2d 794, 796 (Wis. 2004), the Wisconsin Supreme Court held that unless the client consents, a lawyer “cannot waive the attorney-client privilege by voluntarily producing privileged documents (which the attorney does not recognize as privileged) to an opposing attorney in response to a discovery request.” This represents a minority position, but one which can provide protection in those jurisdictions which follow it.
If lawyers make mistakes in document productions, they should explore every possible way to avoid a waiver.