Stephen Hom, a San Francisco police officer, suffered an initial industrial injury to his lumbar spine in 2012 in a prior case. The parties in this prior case settled with Stipulations and Request for a permanent disability Award in the amount of 20% permanent disability based on the findings of Primary Treating Physician Dr. William Campbell, who used using the DRE Metric of the AMA Guides to determine the rating.

In 2013, after his initial injury to his lumbar spine, Officer Hom suffered a second admitted industrial injury to his lumber spine, when he was struck by an oncoming vehicle, while on traffic duty. This second injury is the subject of the current litigated case ADJ10658104.

Dr. David Pang served as the AME in the second case. Dr. Pang utilized the ROM method of the AMA Guides to rate applicant’s current whole person impairment (WPI) at 14%, which rates out to 30% PD.

The primary issue at trial was whether defendant has sustained their burden of proof under LC §4664(b) to allow subtraction of applicant’s prior 20% PD award (calculated using the DRE method) regarding his 2012 injury to his lumbar spine, from his current PD level of 30% (calculated using the ROM method) regarding his 2013 injury to his lumbar spine. WCJ found that “apportionment under LC §4664(b) is not applicable in this case.”

The employer petitioned for reconsideration contending that the WCJ erred by not finding overlap between applicant’s two lumbar spine injuries, The WCJ should have subtracted the 20% Permanent Disability (PD) from the first award, from the 30% PD in the second per the apportionment rule set forth in LC §4664(b). Reconsideration was denied in the panel decision of Hom v City and County of San Francisco.

Labor Code §4664(b) provides, “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. This presumption is a presumption affecting the burden of proof.”

Case law has repeatedly held that defendant has a two-prong burden of proof regarding apportionment under LC §4664(b): (1) Defendant must first prove that a prior award to the same body part exists, AND (2) Defendant must also prove that there is “overlap” of permanent disability between the initial and subsequent injury. This legal standard was set forth in the 3rd DCA case of Kopping v. WCAB (2006) 71 Cal Comp Cases 1229.

In Kopping, the DCA provided an extensive analysis of the seemingly contradictory language of LC §4664(b) and came up with the only interpretation that made sense to them, which was that the defendant has a two-prong burden of proof under LC §4664(b). “…The burden of proving overlap is part of the employer’s overall burden of proving apportionment, which was not altered by section 4664(b), except to create the conclusive presumption that flows from proving the existence of a prior permanent disability award.”

The WCAB affirmed this two-prong analysis for defendant’s burden of proof under LC §4664(b) in the panel decision of Laster v. City and County of San Francisco, 2014 Cal. Wrk. Comp. PD LEXIS 201.

In the writ denied case of Contra Costa County Fire Protection v. WCAB, (Minvielle), (2010), the WCAB interpreted the burden of proving “overlap” of disabilities to mean that the defendant must use the same metric to measure PD on both the initial and subsequent injuries.

Unfortunately, Dr. Pang, has not accurately understood the correct legal theory to apply in this case.