What the panel ordered
Petition for reconsideration denied.
Petition for reconsideration of the Arbitrator's Findings and Award issued on February 2, 2026, denied by the WCAB panel decision dated May 11, 2026.
What was disputed, and how it came out
Each issue the panel decided, with the reasoning it gave. An outcome is what this panel did on this record — not a rule, and not a prediction.
The WCAB found that apportionment under section 4664 by the subtraction method is allowed despite the anti-attribution clause of section 4663(e) because the prior award overlaps the present award and both use the same AMA Guides rating method.
From the decision · page 3II. In addition to the reasons stated by the WCA, we note the following observations. The WCA, in significant part, based the opinion in this matter upon the recent panel decision of Canto Shadoan v. City of San Diego. (91 Cal.Comp.Cases 352, 2025 Cal.Work.Comp. P.D. LEXIX 435 (writ den.).). On April 29, 2026, the Fourth District Court of Appeal denied review in Canto Shadoan with an unpublished opinion expressing agreement with the logic of the case. The WCA did not find apportionment based upon causation in this matter. Both of applicant's disabilities were rated using the exact same method contained in the AMA Guides, which was range of motion. Both AMEs in both cases found that applicant's impairment was 100% industrial in accordance with section 4663(e). Both disability awards are based upon a finding of 100% industrial causation.
The facts that decided it
What the panel treated as outcome-determinative, and which side it favoured.
Applicant's present disability was found 100% industrial by the AME, precluding apportionment based on causation under Labor Code section 4663(e).
Favours Defendant prevailed
This fact precludes apportionment based on causation, limiting apportionment to the subtraction method under section 4664(b).
From the decision · page 3II. In addition to the reasons stated by the WCA, we note the following observations. The WCA, in significant part, based the opinion in this matter upon the recent panel decision of Canto Shadoan v. City of San Diego. (91 Cal.Comp.Cases 352, 2025 Cal.Work.Comp. P.D. LEXIX 435 (writ den.).). On April 29, 2026, the Fourth District Court of Appeal denied review in Canto Shadoan with an unpublished opinion expressing agreement with the logic of the case. The WCA did not find apportionment based upon causation in this matter. Both of applicant's disabilities were rated using the exact same method contained in the AMA Guides, which was range of motion. Both AMEs in both cases found that applicant's impairment was 100% industrial in accordance with section 4663(e). Both disability awards are based upon a finding of 100% industrial causation.
Applicant had a prior industrial injury to the lumbar spine on April 21, 2015, with a permanent disability award of 22% using the AMA Guides ROM method.
Favours Defendant prevailed
The prior award overlaps the present award and supports apportionment by subtraction under section 4664(b).
From the decision · page 921, 2015 sustained an injury arising out of an occur in the course of her employment to her low back resulting in permanent disability of 22% based on the medical report of the Agreed Medical Evaluator Dr. Latteri which rated according to the formula 15.03 - 12(1.4) § 17 - 490I § 23 - 22. Medical reports of Alexander Latteri M.D. case ADJ10194978 Medical report of Alexander Latteri, M.D., dated November 12, 2015:
Both the prior and current awards used the same AMA Guides rating method (ROM) for the lumbar spine.
Favours Defendant prevailed
This overlap in rating method supports the application of apportionment by subtraction under section 4664(b).
From the decision · page 20Again, both Awards were the same part of the body low back, both ratings use the same Method of rating AMA rating the ROM method and therefore based on the medical reports of Dr. Conwisar and Dr. Latteri, defendant has met their burden of proof on the issue of overlap.
What the panel did with the medical opinions
The role the physician served, and the weight the opinion carried. Physicians are named here as the decision names them; we do not score them.
Found applicant's present disability 100% industrial due to cumulative trauma injury through October 20, 2022, and recommended apportionment by subtraction of prior industrial disability from current permanent disability.
The AME found the applicant's present disability 100% industrial and supported apportionment by subtraction method due to overlap with prior industrial injury.
From the decision · page 11As to causation, the physician opined the applicant's lumbar spine, causation is industrial due to the cumulative trauma injury through October 20, 2022, arising out of his employment with the LAPD. The report found the applicant was permanent and stationary and at Maximum Medical Improvements of today's date. The report found the applicant was in need of future medical treatment. As for apportionment, the physician found the applicant had a prior industrial injury
Evaluated prior industrial injury on April 21, 2015, found 22% permanent disability using AMA Guides ROM method, 100% industrial causation, no apportionment to nonindustrial factors.
His medical report established the prior industrial injury and permanent disability rating using the same AMA Guides method as the current award, supporting overlap and apportionment by subtraction.
From the decision · page 921, 2015 sustained an injury arising out of an occur in the course of her employment to her low back resulting in permanent disability of 22% based on the medical report of the Agreed Medical Evaluator Dr. Latteri which rated according to the formula 15.03 - 12(1.4) § 17 - 490I § 23 - 22. Medical reports of Alexander Latteri M.D. case ADJ10194978 Medical report of Alexander Latteri, M.D., dated November 12, 2015:
The rules the panel named
Authorities as the decision cited them, with how this panel applied each one.
Labor Code section 4664(b)
Labor Code section 4664(b) allows apportionment by subtraction of prior permanent disability awards when there is overlap using the same AMA Guides rating method.
The WCAB applied section 4664(b) to allow apportionment by subtraction of prior awards overlapping the current award using the same AMA Guides method.
From the decision · page 20Therefore, apportionment is allowed by the subtraction method to the prior Award of 22% permanent disability pursuant to the case of Kopping v. Workers' Comp. Appeals Bd.
Labor Code section 4663(e)
Labor Code section 4663(e) anti-attribution clause precludes apportionment based on causation of disability.
The WCAB found that apportionment based on causation is precluded under section 4663(e) but apportionment under section 4664(b) by subtraction is allowed.
From the decision · page 3II. In addition to the reasons stated by the WCA, we note the following observations. The WCA, in significant part, based the opinion in this matter upon the recent panel decision of Canto Shadoan v. City of San Diego. (91 Cal.Comp.Cases 352, 2025 Cal.Work.Comp. P.D. LEXIX 435 (writ den.).). On April 29, 2026, the Fourth District Court of Appeal denied review in Canto Shadoan with an unpublished opinion expressing agreement with the logic of the case. The WCA did not find apportionment based upon causation in this matter. Both of applicant's disabilities were rated using the exact same method contained in the AMA Guides, which was range of motion. Both AMEs in both cases found that applicant's impairment was 100% industrial in accordance with section 4663(e). Both disability awards are based upon a finding of 100% industrial causation.
What proof carried it
The evidence the panel weighed, by kind.
Both Awards were for the same body part (low back) and used the same AMA Guides ROM rating method, supporting overlap for apportionment.
From the decision · page 20Again, both Awards were the same part of the body low back, both ratings use the same Method of rating AMA rating the ROM method and therefore based on the medical reports of Dr. Conwisar and Dr. Latteri, defendant has met their burden of proof on the issue of overlap.
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About this page
- A published decision of the California Workers' Compensation Appeals Board, taken apart by what it turned on. The Board publishes the decision itself; this page adds the extraction and quotes the passage behind every claim.
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