Apportionment per Labor Code Section 4664

The Workers’ Compensation Appeals Board granted reconsideration in the case of Jose Nieves v. City of Hayward (ADJ8731516), and on October 17, 2018, issued its opinion and decision upholding the trial judge’s apportionment in reliance on Labor Code Section 4664.

The applicant was a backhoe operator for the City of Hayward. He filed a cumulative trauma claim through August 30, 2012 regarding both internal and orthopedic body parts.

The internal Agreed Medical Examiner did not find any basis for apportionment, despite applicant’s prior Award dated October 21, 2009 for 15% permanent disability due to a hernia. The Workers’ Compensation Judge took judicial notice of the Award and found 47% permanent disability after apportionment to applicant’s prior industrial injuries per Labor Code Section 4664(b).

The applicant filed a Petition for Reconsideration claiming that he was permanently totally disabled per the conclusions of his vocational expert, that defendant did not prove overlap of disabilities allowing for apportionment under Labor Code Section 4664, and that costs awarded to applicant’s vocational expert were insufficient.

The WCJ recommended denial of the Petition for Reconsideration stating that although the internal medicine AME limited the applicant’s lifting based on a hernia, he did not restrict the applicant to sedentary work, and the vocational expert incorrectly assumed so when he issued his report that found a 100% loss of future earning capacity.

The WCAB panel stated that Section 4664(b) establishes apportionment to prior awards of permanent disability existing at the time of any subsequent industrial injury and that the defendant must prove both the existence and overlap of the permanent disability caused by the two injuries.

In this instance the internal medicine AME mentioned prior hernias as a risk factor making the subsequent hernia to be more likely but not the cause of the 2012 hernia. The WCAB stated that:

The presence of overlap is evidenced by the “risk factor” of prior hernias and prior surgical procedures as opined by Dr. Besses. Thus, apportionment pursuant to section 4664(b) was properly applied by the WCJ.

The panel also agreed that the vocation expert reporting did not establish that the applicant is not amenable to vocational rehabilitation and thus did not rebut the PDRS rating. However, the panel disagreed with the value of costs awarded to the expert and ordered the defendant to pay reasonable costs.


The burden of proof is on the defendant to show apportionment to a prior industrial injury per Labor Code Section 4664(b) and it requires more than a showing of injury to the same body parts. In this case, a risk factor mentioned by the AME was enough to meet that burden. In seeking Section 4664(b) apportionment it is imperative to be aware of the language used in the doctor’s report being relied upon for apportionment and to ask for clarification if it does not meet the burden of proof.

Amanda Rocha, Attorney
GMK, San Luis Obispo

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