Butler: Apportionment Failed Where the Medical History Remained Unresolved

Review the primary official source.

In Butler v. State of California, Department of Toxic Substances Control, the Workers’ Compensation Appeals Board denied reconsideration and adopted the workers’ compensation judge’s report. The report found that the defense had not carried its burden to prove nonindustrial apportionment with substantial medical evidence.

The physicians relied on different histories

The medical record included opinions addressing cognitive, sleep, psychiatric, and other impairments. Some evaluators assigned a percentage to asserted nonindustrial alcohol use or life stressors, while another evaluator identified a history he had not previously known and called for confirmation.

The applicant did not testify at trial, and no supplemental reporting reconciled the materially different accounts. The judge therefore could not determine which historical premise was accurate.

Possibility did not satisfy the apportionment burden

The adopted report applied Labor Code section 4663 and the substantial-evidence standard. An apportionment opinion must explain how and why nonindustrial factors caused a percentage of permanent disability and must rest on an accurate factual foundation.

Because the competing history remained unresolved, the report treated the proposed ten-percent allocations as speculative. It also explained that an opinion may be insufficient on apportionment while remaining usable on causation or impairment if those portions are independently supported.

The impairment rating was treated as a straight Guides rating

The defense also challenged the sleep-related rating. The report concluded that the sleep specialist used the AMA Guides chapter he considered medically applicable to the diagnosed endocrine dysfunction rather than departing from the Guides through an alternative Almaraz/Guzman method.

On that record, the report found no separate Almaraz/Guzman analysis necessary. That conclusion turned on the physician’s explanation of diagnosis, causation, the selected chapter and table, and activities-of-daily-living effects.

Build history before the record closes

Ask evaluators to identify each factual assumption, source, diagnosis, causal pathway, and percentage. When histories conflict, use testimony, records, or supplemental reports to reconcile them before submission rather than asking the judge to select among unsupported premises.

The decision also discusses the version of section 5909 then governing the Board’s action deadline. It is a panel decision rather than binding en banc precedent, and its medical-rating analysis depends on the particular reports adopted in this record.