The doctrines of res judicata and collateral estoppel can bar parties from re-litigating claims and issues that were decided previously in workers' compensation proceedings. Res judicata, or claim preclusion, acts to bar claims that were, or should have been, advanced in a previous suit involving the same parties. It arises if a second suit: (1) involves the same cause of action; (2) is between the same parties; and (3) occurs after a final judgment on the merits. (DKN Holdings LLC v. Faerber (2015) 61 Cal. 4th 813, 824.)
Collateral estoppel, or issue preclusion, bars re-litigating issues that were argued and decided in the first suit. It does not bar entire causes of action. It prevents re-litigation only of previously decided issues. Collateral estoppel applies after final adjudication of an identical issue actually litigated and necessarily decided in the first suit, and asserted against a party in the first suit or one in privity with that party. (DKN Holdings LLC v. Faerber (2015) 61 Cal. 4th 813, 824-825.) To apply collateral estoppel, a five-part test applies requiring proof that: (1) the issue sought to be precluded from re-litigation must be identical to that decided in a former proceeding; (2) the issue must have been actually litigated in the former proceeding; (3) it must have been necessarily decided in the former proceeding; (4) the decision in the former proceeding must be final and on the merits; and (5) the party against whom preclusion is sought must be the same as, or in privity with, the party to the former proceeding. (Pacific Lumber Co. v. State Water Resources Control Board (2006) 37 Cal.4th 921, 943.).
A recurring question in workers' compensation is whether a prior findings and award that is silent as to certain claimed body parts operates as a final, on-the-merits decision precluding those claims from being litigated in subsequent proceedings. Two recent panel decisions, Barrick v. California Department of Public Health, 2026 Cal. Wrk. Comp. P.D. LEXIS 71, and Melendez v. Kellermeyer Bergensons Services, LLC, 2026 Cal. Wrk. Comp. P.D. LEXIS 99, address the collateral estoppel question directly. Read together, these decisions establish that a prior award's silence as to a body part is not a decision on the merits as to that body part, and that the failure to include findings regarding additional claimed body parts does not give rise to collateral estoppel.
THE BARRICK CASE
In Barrick, the applicant filed an application for adjudication of claim, claiming cumulative injury to his psyche, brain, nervous system and other body systems during his employment as a contract manager through Jan. 30, 2018. The matter proceeded to trial, with the parties stipulating that the applicant claimed injury to his psyche, brain, stress, nervous system and body systems. The June 2021 F&A addressed only the applicant's psychiatric injury, awarding 49 percent permanent disability and future medical treatment to the psyche. In the opinion on decision, the WCJ stated that "[n]o evidence was presented to show industrial injury to any other body part." The judge made no findings, orders or award regarding the applicant's other claimed body parts, and ordered all other issues deferred with jurisdiction reserved.
Following the 2021 decision, the applicant filed an amended application in October 2021, identifying encephalitis, meningitis and lymphoma as additional claimed conditions, followed by a second amended application in February 2022 that specified the associated body parts in detail. The defendant moved to dismiss the amended application on the grounds of res judicata and collateral estoppel, arguing that the body parts had been at issue in the 2021 trial and, therefore, were decided. The WCJ agreed, dismissed the amended application without prejudice, and found that the applicant was barred from re-litigating the question of injured body parts. The applicant sought reconsideration.
The WCAB granted reconsideration and rescinded the WCJ's decision. It held that collateral estoppel, rather than res judicata, was the applicable doctrine, as the question was not whether the additional body parts had been raised at trial in 2021, but whether they actually had been decided. It found that two of the elements for collateral estoppel — that the issue necessarily must have been decided in the former proceeding, and that the decision must be final and on the merits — were not satisfied. It found that the 2021 decision included no findings regarding the brain, nervous system or other body systems, and expressly had ordered all other issues deferred with jurisdiction reserved. The WCAB added that the discussion of body parts in the opinion on decision did not constitute a finding on the merits, stating, "Without findings, there is nothing legally enforceable with respect to the brain, nervous system and body SMS." It concluded that the question of whether the applicant sustained injury AOE/COE to his claimed body parts other than psyche was not decided by the original decision, and he was free to litigate the additional claims until final findings as to each claimed body part are issued.
THE MELENDEZ CASE
In Melendez, the applicant sustained industrial injury July 19, 2004. The case was litigated over many years. In a 2013 trial, it was stipulated that the applicant sustained injury AOE/COE to the low back, psyche and right shoulder, and the disputed issue was injury to the right ankle. In October 2014, the WCAB issued a decision after reconsideration, finding no injury to the right ankle and awarding further medical treatment. Thereafter, the parties resolved the indemnity issues through a compromise and release in March 2020, which expressly preserved all body part disputes and future medical care issues. The case eventually proceeded to a 2021 trial at which the applicant claimed additional injury to her teeth, jaw, brain, sleep, kidneys, left shoulder, high blood pressure and head, in addition to diabetes and chronic regional pain syndrome. The WCJ found injury to the left shoulder and chronic pain syndrome, and the defendant sought reconsideration, asserting that those claims were barred by res judicata and collateral estoppel based on the 2014 decision.
The WCAB affirmed the WCJ's decision after granting reconsideration. Applying the same framework, the WCAB held that collateral estoppel was at issue, not res judicata, because the question was whether injury to the left shoulder and chronic pain syndrome had been decided in 2014, not whether those claims had been raised in an earlier proceeding. It found that the 2014 decision made no findings regarding the left shoulder or chronic pain syndrome because that body part and that syndrome had never been raised or litigated in the 2012 and 2013 trial proceedings, and neither the WCJ's 2013 findings nor the WCAB's 2014 findings included any determination that the applicant had not sustained injury to any other body parts. Accordingly, there was no final decision on the merits as to those body parts, and no basis for preclusion.
The WCAB further held that continuing jurisdiction under LC 5803 supported the WCJ's findings. If there is an existing award for further medical treatment, the WCAB may require an employer to provide treatment for a compensable consequence of the industrial injury even if that condition was not part of the original award, and even if the injured employee first requests treatment more than five years after the date of injury.
ANALYSIS
Barrick and Melendez both apply collateral estoppel in the same manner, and hold that silence regarding body parts is not a decision on the merits. A prior findings and award that addresses only certain body parts — whether other parts were deferred, not raised or simply not reached — is not a final decision on the merits as to the unaddressed parts. Even in a case such as Barrick, in which the opinion on decision contains narrative language suggesting that the applicant did not meet the burden of proof as to other body parts, the WCAB will not deem those parts to be "necessarily decided" unless the WCJ issues a specific formal finding regarding them. These decisions make clear that a narrative discussion in an opinion on decision is not the equivalent of a formal finding. If the WCJ has discussed but not formally found against a body part claim, that claim remains available for future litigation.
Both decisions, however, leave unresolved a significant statutory tension that practitioners should be prepared to address in future cases. LC 5815 mandates that every order, decision or award "shall contain a determination of all issues presented for determination." Moreover, it states, "Any issue not so determined will be deemed decided adversely as to the party in whose interest such issue was raised." In Barrick, the WCAB quoted that provision but did not apply it, instead relying on the WCJ's express deferral order to avoid the adverse-decision consequence. In Melendez, the provision was not addressed at all. Neither decision engaged with the question of what LC 5815 requires when a WCJ fails to issue findings on a body part that was squarely presented as a trial issue — whether the statutory adverse-decision consequence attaches, and if so, whether that consequence constitutes the "final decision on the merits" necessary to satisfy collateral estoppel.
The Barrick decision's reliance on the WCJ's order that "All other issues are deferred" to sidestep LC 5815 might be defensible on the facts of that case. Separately, Melendez adds the dimension of the WCAB's continuing jurisdiction under LC 5803, which operates independently of the preclusion doctrines. Even when a claim arises years after the date of injury, if there's an existing award for further medical treatment and the new condition is a compensable consequence of the original industrial injury, the WCAB retains jurisdiction to require treatment for that condition regardless of the passage of time.
Nevertheless, if body parts previously were raised for trial, a strict reading of LC 5815 would suggest that undecided issues in a nondeferring award are automatically decided adversely to the party who raised them — in body part claims, that means the applicant. If that reading is correct, a previous award that is simply silent as to a body part, without expressly deferring jurisdiction, could operate as a denial of that body part under LC 5815, and the collateral estoppel analysis could reach a different conclusion from the one Barrick and Melendez reached on their facts.
Practitioners should note that neither Barrick nor Melendez is binding. Although both are citable, their application might be fact-dependent, and the unresolved interplay with LC 5815 means that further development in this area should be anticipated.
For further discussion on the application of res judicata and collateral estoppel in workers' compensation proceedings, see Sullivan on Comp Section 16.41 Award — Timing, Content and Legal Effect.
