Workers’ Compensation · Primary-source case analysis

Vargas: New Apportionment Law Applied to Increased Disability on Reopening

By Aneeta Mishra and Timothy Chan

Published April 28, 2026 · Updated October 17, 2026

Decision: Vargas v. Atascadero State Hosp., No. GRO 0016640 (WCAB Apr. 11, 2006) (en banc).

Vargas separates two questions: Can a final disability award be reduced because the law changed, and which law governs a still-pending claim for increased disability? The Board protected the original final award while applying the new apportionment rules to the claimed increase.

A petition to reopen was pending when the law changed

Myrtle Vargas sought increased permanent disability within the statutory reopening period. Senate Bill 899 took effect while that claim remained unresolved.

New apportionment rules governed the increase

The Board applied Senate Bill 899’s new causation-based apportionment rules to a petition still unresolved when the law took effect on April 19, 2004. Those rules divide responsibility according to the causes of permanent disability. The original injury date did not control this transition question. Vargas, slip opinion, pages 1–2, 6.

The final original award remained intact

Vargas’s January 1998 award fixed permanent disability at 67 percent, without apportionment. The new law could not be used to reduce or recalculate those final findings. It governed the claimed increase, which still required substantial medical evidence of the causes of that increased disability. Vargas, slip opinion, pages 2–3, 7–9.

Disposition

The WCAB denied removal and directed that increased disability be determined under the new apportionment rules without reference to how the original award handled apportionment.

Key takeaways

• Separate original disability from the claimed increase.
• Confirm when the original award became final.
• Apply the law governing the pending reopening issue.
• Do not use the new law to recalculate findings already fixed in a final pre-amendment award.