The interplay of apportionment as applied by Labor Code Sections 4663 and 4664 continues to draw attention from the WCAB. Below is a summary of recent panel decisions regarding apportionment as applied by both Labor Code Sections 4663 and 4664.

Sperry v. San Diego Unified Port District/American Home Assurance Co.

In Sperry v. San Diego Unified Port District/American Home Assurance Co., ADJ11046834 (SDO) July 22, 2026, the WCAB determined a police officer was not owed additional disability, when defendants met the burden of proof showing that the prior and current impairment was completely overlapping. No additional permanent disability was owed for a second back injury following a prior award for Permanent Disability. Applicant’s attorney argued that Labor Code §4663(e), as it relates to duty-belt presumptions outlined in Labor Code §3213.2, barred any form of apportionment, including apportionment to a prior award under §4664(b). The WCAB determined that the prior lumbar award was completely overlapping with the current lumbar impairment, and that it was not the legislative intent that §4663(e) prevent apportionment from being applied to prior awards as outlined in §4664(b).

Gonzalez v. City of Los Angeles

In Karina Gonzalez v. City of Los Angeles, ADJ22325507 (LAO) March 9, 2026, the WCAB denied applicant’s petition for reconsideration of apportionment pursuant to Labor Code §4664(b). Applicant, a police officer, suffered a low back injury which resulted in 35% Permanent Disability. Applicant had received a prior award for a low back injury which resulted in 22% Permanent Disability. Applying Labor Code §4664(b), the board awarded a final impairment of 13% Permanent Disability. Similarly to the facts in Sperry, applicant argued that Labor Code §4663(e) precludes apportionment under §4664(b), due to the presumptions allowed pursuant to Labor Code §3212.2. The WCAB rejected applicant’s argument, noting that the applicant’s industrial disability warranted subtraction under §4664(b), as there was factual overlap between the past and present industrial disability.

Snow v. City of Modesto

In Michael Snow v. City of Modesto, ADJ14815013 (LOD) March 16, 2026, the WCAB returned the case to the trial judge for further development of the record regarding apportionment as applied by Labor Code §4664. Applicant, a fire engineer, experienced an injury to his neck and right shoulder which resulted in permanent impairment. This disability was reduced by a prior award the applicant received for injury to his neck and right shoulder.

Applicant filed a petition for reconsideration, arguing that defendant failed to meet its burden of showing that the applicant’s permanent disability overlapped with his prior award for disability for the neck and right shoulder. The permanent impairment provided for applicant’s the prior and present awards were analyzed using different methods.

The WCAB ultimately returned the matter to the trial level, opining that the record should be further developed to support any argument for overlap of the previous and present disability. Where the medical legal evaluators applied two different methods for determining impairment, the WCAB noted that the evaluator should address apportionment to support whether the prior impairment can be “translated” to into a range of motion impairment. Because two different methods were used to provide impairment for the applicant’s two dates of injury, the WCAB opined that the record needed further development to support overlap of the disability between the two dates of injury.

Shadoan v. City of San Diego

In Canto Shadoan v. City of San Diego, 2025 Cal. Wrk. Comp. P.D. LEXIS 435, the WCAB applied Labor Code §4664 for subtracting a prior award of 9% Permanent Disability from the applicant’s current disability of 24%. The WCAB outlined requirements for defendants for supporting apportionment, noting, “where defendant proves that a prior award of disability exists and proves that the prior award of disability overlaps with the current award, defendant is entitled to subtract the prior award of overlapping permanent disability from applicant’s current award.” When addressing Labor Code §4664(b) and its effect on Labor Code §4663(e), the Board further opined, “As the basis for apportionment under section 4664(b) does not analyze the cause of the disability, section 4663(e) does not preclude its application.” The WCAB ultimately rescinded the lower court’s Findings and Award, creating a new finding that applies apportionment as allowed under Labor Code §4664.