Q: Is unlisted witness testimony allowed in workers' comp hearing in WA?

A: What you're describing raises some serious concerns about fairness and proper procedure. In Washington workers’ compensation hearings, parties are generally required to disclose their witness lists in advance, especially when expert testimony is involved. The Board of Industrial Insurance Appeals (BIIA) rules require timely filing and service of witness confirmations so all parties have a fair chance to prepare. If the opposing side presented a witness not disclosed on their list, that can be grounds for challenging the validity of the testimony.

Even though you didn’t object during the hearing, you can still raise the issue in your Petition for Review—particularly if you only discovered the oversight afterward. Washington courts and the BIIA recognize that due process matters, and if you were surprised by an unlisted witness, especially an expert, you can argue that you were denied a fair opportunity to respond or prepare rebuttal. The fact that the other party said they wouldn’t participate but still showed up and used testimony can further support your argument.

In your petition, clearly explain the discrepancy and how it may have affected the outcome. Reference the rule requiring witness confirmations and emphasize that the testimony should not have been admitted without prior disclosure. You have every right to insist that the process be fair and transparent, and this could be a strong point for review.