Workers’ Compensation · Primary-source case analysis

Nunes: What if the Physician’s Apportionment Opinion Fails?

By Aneeta Mishra and Timothy Chan

Published September 2, 2026 Updated October 3, 2026

Decision: Nunes v. State of California, Department of Motor Vehicles, Nos. ADJ8210063 and ADJ8621818 (WCAB Aug. 29, 2023) (en banc).

The remand addressed missing findings

The August 2023 en banc Nunes opinion reviewed a challenge to the Board’s June remand. The workers’ compensation judge had not adequately resolved permanent disability and apportionment for the worker’s separate injury claims or explained the evidentiary basis for those findings as Labor Code section 5313 requires. The petition did not show that returning the matter for a reasoned record was error. Nunes, slip op. at 3.

A medical opinion is not presumed valid

The Board rejected the notion that “otherwise valid” medical apportionment means a physician’s percentages must be accepted without scrutiny. A medical opinion must rest on reasonable medical probability, pertinent facts, an adequate history and examination, and an explanation of how and why the identified factors cause disability. The judge must decide whether that opinion is substantial evidence on the whole record. Id. at 3–4.

Development or an unapportioned award depends on the record

If no evaluating physician identifies legally valid apportionment, a vocational expert cannot supply independent percentages. If the physician’s proposed apportionment lacks substantial evidence and further development is unwarranted, the worker is entitled to an unapportioned award. Conversely, Nunes itself required further proceedings because the trial findings and record were inadequate. The opinion does not command a supplemental report in every case of deficient medical apportionment. Id. at 3–5.

The particular vocational dispute remained unresolved

Both vocational experts proposed apportionment that differed from the evaluator’s account. The Board did not decide whether the evaluator’s opinion was valid. It noted that her discussion of diabetes concerned carpal tunnel syndrome, while one vocational analysis emphasized cervical spine and shoulder limitations; the parties may seek her additional opinion about the factors behind retraining non-feasibility. A vocational expert may also analyze alternatives when the medical opinion’s validity is genuinely disputed. Id. at 7–8, 11. For the underlying division of medical and vocational roles, see our companion analysis.

Key takeaways

• Ask whether the physician explains each apportionment factor with substantial medical evidence.
• Do not substitute a vocational expert’s percentages for the statutory medical determination.
• Choose record development only where the record warrants it; invalid apportionment may instead lead to an unapportioned award.
• Read the remand as leaving this worker’s ultimate disability and medical-apportionment findings open.