For more than two decades, the law governing the identification of liable parties has been shaped by the Workers' Compensation Appeals Board’s en banc decisions in Coldiron v. Compuware Corp. In Coldiron I,[1] the WCAB held that a third-party administrator (TPA) has a duty to disclose the identity of its client — whether a self-insured employer or an insurance carrier. Crucially, if the client is an insurance carrier, the TPA also must disclose whether the policy includes a "high self-insured retention," a large deductible or any other provision that affects the identity of the entity ultimately liable for payment. The WCAB warned that failure to do so could result in sanctions.
In Coldiron II,[2] the WCAB declined to impose sanctions, as it was a case of first impression, but reiterated that the disclosure holdings remained in full force and effect.
The principles from Coldiron were foundational to the creation of the California Code of Regulations, Title 8, § 10390,[3] which requires that pleadings and documents identify the insurer and/or employer as the proper party, and not identify a TPA as a party. But the regulation’s language, which focuses on properly naming the parties, created ambiguity as to whether it superseded the more detailed disclosure requirements mandated by Coldiron. That led some parties to argue that merely naming the insurance carrier was sufficient to comply with the law.
On Oct. 13, 2025, the WCAB issued an en banc decision in Difusco v. Hands On Spa, resolving this ambiguity. It held that CCR 10390 does not supersede Coldiron and that the detailed disclosure requirements articulated in that case remain binding precedent. Furthermore, the WCAB clarified that those disclosure obligations apply to all defendants, regardless of whether a TPA is involved.
In Difusco, the applicant had been awarded home health-care services, but the provider was not being paid. The applicant’s attorney sent a discovery request to the defense, citing the Coldiron decisions, and asked for detailed information about the insurance coverage, including policy limits, primary and secondary excess carriers and any other potential payors.
The defendant’s attorney refused to provide the information, arguing that CCR 10390 had superseded Coldiron. Defense counsel contended that it had complied with the law by simply identifying the insurance carrier and that no further disclosure was required. The matter proceeded to trial, where the workers’ compensation judge (WCJ) agreed with the defendant, finding that CCR 10390 had indeed superseded the Coldiron decisions. The applicant filed a petition for reconsideration.
The WCAB granted reconsideration and issued an en banc decision to clarify the law and ensure uniformity. It held that its en banc decisions are binding precedent with the same force as published appellate court opinions and cannot be superseded by a regulation. It stated that en banc precedent remains binding unless it is rescinded by the WCAB en banc, overturned by a higher court or rendered inapplicable by legislative action.
The WCAB explained that CCR 10390 and the Coldiron decisions are not in conflict and must be read together. CCR 10390’s purpose is to ensure the proper identification of parties in pleadings, while clarifying that a TPA is not a party. The Coldiron decisions, in contrast, address the broader and more fundamental requirement to disclose the details of liability to ensure that the correct entity can be held responsible for payment.
Most significant, the WCAB held that the Coldiron disclosure requirements — including the duty to reveal high self-insured retentions, large deductibles and other provisions affecting liability — apply to all defendants, not only those utilizing a TPA. It concluded that the defendant had a duty to respond to the applicant's discovery request and that the information was essential for the enforcement of the applicant's awarded benefits.
The WCAB stated, "When an applicant seeks information about the liable entity or the insurance policy provisions, the information should be readily provided." It added, "The WCJ has a duty to inquire and ensure that the record reflects the correct identity of all parties, at first opportunity, including at the mandatory settlement conference and at trial." The WCJ's decision was rescinded, and the matter was returned to the trial level with an order for the defendant to disclose the requested information.
The en banc decision in Difusco provides critical clarification and reinforcement of a defendant's disclosure obligations. It firmly establishes that the duties defined in Coldiron are not mere artifacts but are alive, well and expanded. Defendants no longer can argue that simply naming the insurance carrier in a caption satisfies their legal obligations when confronted with a discovery request for more detailed liability information.
This ruling is a victory for applicants and lien claimants, who often face payment delays or denials without understanding the complex insurance structures behind the claim. By affirming that defendants must disclose details such as self-insured retentions and excess carrier involvement, the WCAB ensures that the burden of identifying the correct payor rests with the defense, which holds the information, not with the injured worker.
For defense practitioners, Difusco serves as a clear warning. A refusal to disclose insurance liability details after a proper request is a violation of binding precedent and might subject a party to sanctions. The decision emphasizes that full transparency is not optional; it is fundamental to the "prompt delivery of benefits" that the workers' compensation system is designed to provide. Going forward, all parties must ensure that discovery responses regarding insurance coverage are complete and candid, consistent with the enduring principles of Coldiron as affirmed and expanded by Difusco.
For further discussion on the requirement to disclose liable parties, see "Sullivan on Comp" Section 15.71 Legal Representation Before Appeals Board.