No former employee of the agency shall, at any time after severing his or her employment with the state of Washington appear, except with the written permission of the agency, as an expert witness on behalf of other parties in a formal proceeding wherein the former employee previously took an active part in the investigation as a representative of the agency.
Wash. Admin. Code § 446-08-060
Order II, § 446-08-060, filed 11/22/74.