Workers’ Compensation · Primary-source case analysis

Nunes: Vocational Evidence Cannot Replace Valid Medical Apportionment

By Aneeta Mishra and Timothy Chan

Published September 2, 2026

Nunes v. State of California, Department of Motor Vehicles returned to the WCAB after its June 2023 en banc decision addressed the proper relationship between medical apportionment and vocational evidence. The August opinion denied reconsideration and clarified why a vocational expert may evaluate disability evidence but may not create an alternative apportionment method that bypasses the statutory medical inquiry.

Section 4663 assigns apportionment to physicians

Labor Code section 4663 requires a reporting physician to identify the approximate percentage of permanent disability caused by the industrial injury and by other factors. The medical opinion must explain how and why those factors caused disability and must constitute substantial evidence before it can support an award.

Vocational evidence still has a proper role

A vocational expert may analyze whether the medical restrictions and labor-market evidence establish diminished future earning capacity or rebut a scheduled rating. The expert may also explain why particular medical restrictions affect employability. That role does not authorize the expert to decide medical causation.

An invalid medical opinion must be corrected, not ignored

If the physician's apportionment analysis is conclusory or otherwise fails the substantial-evidence standard, the record ordinarily requires further medical development. A vocational expert cannot cure the defect by announcing that all vocational disability is industrial or by applying a separate apportionment formula.

The en banc rule controlled the pending dispute

The Board rejected arguments that the June decision had improperly changed the law and denied reconsideration. The opinions together direct parties and judges to evaluate medical apportionment first, then decide what reliable vocational evidence adds to the permanent-disability analysis.

Key takeaways

• Test every apportionment opinion for a reasoned medical explanation.
• Keep medical causation separate from vocational feasibility and earning capacity.
• Seek a supplemental medical report when the physician's analysis is not substantial evidence.
• Frame vocational rebuttal around the medical restrictions actually established in the record.