California Labor Code § 4664

Determinative passage · p.6(Gatten) (2006) 145 Cal.App.4th 922, 927–928 [71 Cal.Comp.Cases 1687].) Instead, apportionment of permanent disability is “based on causation” and the “employer shall only be liable for the percentage of permanent disability directly caused by the injury arising out of and occurring in the course of employment.” (Lab. Code, §§ 4663(a) and 4664(a).) “The plain reading of ‘causation’ in this context is causation of the permanent disability.” (Escobedo v. Marshalls (Escobedo) (2005) 70 Cal.Comp.Cases 604, 611 (Appeals Board en banc).) Apportionment now includes pathology, asymptomatic prior conditions, and retroactive prophylactic work preclusions, provided there is substantial evidence establishing that these other factors have caused permanent disability. Pursuant to Escobedo, a physician's opinion must rely on reasonable medical probability, cannot be speculative, must rely on pertinent facts and/or an adequate examination and history, and must set forth the reasoning in support of its

The WCJ applied these statutes to uphold Dr. Sommer's apportionment opinion and reject vocational apportionment.

Determinative passage · p.5Pursuant to section 4664(b), if the applicant has received a prior award of permanent disability, “it shall be conclusively presumed that the prior permanent disability exists at the time of any subsequent industrial injury.” Here, applicant’s June 8, 2020 injury could not have been a contributing factor to permanent disability that existed prior to that injury date. While later identified apportionment as part of new and further disability proceedings may not be retroactively applied to an underlying permanent disability that was the subject of a finalized award, it nonetheless may be applicable to new and further permanent disability beyond that which was previously awarded.

The Board held that apportionment cannot retroactively reduce the prior award but may apply to new and further disability.

Determinative passage · p.13Cal.4th 1313, 1321 [72 Cal.Comp.Cases 565]; Marsh v. Workers’ Comp. Appeals Bd. (2005) 130 Cal.App.4th 906, 911 [70 Cal.Comp.Cases 787.].) The mere fact that a medical report assigns approximate percentages of industrial and nonindustrial causation does not make the report reliable medical evidence by itself. (E.L. Yeager Construction v. Workers' Comp. Appeals Bd. (Gatten) (2006) 145 Cal.App.4th 922, 927–928 [71 Cal.Comp.Cases 1687].) Instead, apportionment of permanent disability is “based on causation” and the “employer shall only be liable for the percentage of permanent disability directly caused by the injury arising out of and occurring in the course of employment.” (Lab. Code, §§ 4663(a) and 4664(a).) “The plain reading of ‘causation’ in this context is causation of the permanent disability.” (Escobedo v. Marshalls (Escobedo) (2005) 70 Cal.Comp.Cases 604, 611 (Appeals Board en banc).) Apportionment now includes pathology, asymptomatic prior conditions, and retroactive prophylactic work preclusions, provided there is substantial evidence establishing that these other factors have caused permanent disability. Pursuant to Escobedo, a physician's opinion must rely on reasonable medical probability, cannot be speculative, must rely on pertinent facts and/or an adequate examination and history, and must set forth the reasoning in support of its conclusions. (Id. at p.

The Board applied this standard to evaluate the apportionment evidence and burden of proof.

Determinative passage · p.18Based on the opinion of primary treating physician Larry Dodge, M.D., applicant has 13 percent whole person impairment to her lumbar spine under the AMA Guides for the cumulative injury from November 3, 2003 through November 3, 2004. 8. Based on the opinion of qualified medical examiner Beth Bathgate, M.D., applicant’s cumulative injury from November 3, 2004 through September 11, 2017 caused whole person impairment of 13 percent under the AMA Guides. 9. Defendant has met its burden of establishing a total overlap between past and current injuries and thus has met it burden to show apportionment under section 4664(b). 10. Applicant has not suffered any additional permanent impairment or resulting permanent partial disability from the November 3, 2004 through September 11, 2017 industrial injury.

Apportionment to prior awards of permanent disability requires proof of overlap between prior and current injuries.

Determinative passage · p.10(Gatten) (2006) 145 Cal.App.4th 922, 927–928 [71 Cal.Comp.Cases 1687].) Instead, apportionment of permanent disability is “based on causation” and the “employer shall only be liable for the percentage of permanent disability directly caused by the injury arising out of and occurring in the course of employment.” (Lab. Code, §§ 4663(a) and 4664(a).) “The plain reading of ‘causation’ in this context is causation of the permanent disability.” (Escobedo v. Marshalls (Escobedo) (2005) 70 Cal.Comp.Cases 604, 611 (Appeals Board en banc).) Apportionment now includes pathology, asymptomatic prior conditions, and retroactive prophylactic work preclusions, provided there is substantial evidence establishing that these other factors have caused permanent disability.

Employer liable only for PD directly caused by industrial injury; apportionment includes pathology and prior conditions with substantial evidence.

Determinative passage · p.14Apportionment is the process utilized to segregate permanent disability or the residuals caused by an industrial injury from those attributable to other industrial injuries or to nonindustrial factors, to allocate legal responsibility fairly. (Brodie v. Workers’ Comp. Appeals Bd. (2007) Cal.4th 1313, 1321 [72 Cal.Comp.Cases 565]; Marsh v. Workers’ Comp. Appeals Bd. (2005) 130 Cal.App.4th 906, 911 [70 Cal.Comp.Cases 787.].) A medical evaluator must parcel out industrial and non-industrial causation of permanent disability. (E.L. Yeager Construction v. Workers’ Comp. Appeals Bd. (Gatten) (2006) 145 Cal.App.4th 922, 927 [71 Cal.Comp.Cases 1687].) Apportionment of permanent disability is “based on causation” and the “employer shall only be liable for the percentage of permanent disability directly caused by the injury arising out of and occurring in the course of employment.” (Lab.

Apportionment is based on causation of permanent disability; employer liable only for disability caused by employment injury.

Determinative passage · p.4(c) (1) The accumulation of all permanent disability awards issued with respect to any one region of the body in favor of one individual employee shall not exceed 100 percent over the employee's lifetime unless the employee's injury or illness is conclusively presumed to be total in character pursuant to Section 4662. As used in this section, the regions of the body are the following:

The Board reviewed the application of section 4664(c) to prior awards and apportionment in this case.

Determinative passage · p.6In addition, section 4664 provides that "[i]f the applicant has received a prior award of permanent disability, it shall be conclusively presumed that the prior permanent disability exists at the time of any subsequent industrial injury." (Lab. Code, § 4664 (b).) "Section 4664(b) creates a conclusive presumption of the continued existence of a prior permanent disability when the claimant received an award of permanent disability benefits based on that disability," and that defendant "has the burden of proving overlap between the current disability and the previous disability in order to establish its right to apportionment...." (Kopping v. Workers' Comp. Appeals Bd. (2006) 142 Cal.App.4th 1099, 1115 [71 Cal.Comp.Cases 1229].)

The WCAB found the medical opinions did not meet the substantial evidence standard for apportionment because they lacked adequate explanation of causation and overlap.