ADJ21635072 · January 5, 2026

The anti-attribution clause in Labor Code 4663(e) precludes apportionment to prior awards for presumptively compensable injuries; defendant failed to provide substantial evidence of overlap to meet burden of proof for apportionment under Labor Code 4664(b).

From the decision · page 73. The Arbitrator found that apportionment pursuant Labor Code § 4664(b) to a prior permanent disability Award to the lumbar spine is precluded by the anti-attribution clause in Labor Code § 4663(e), and therefore the applicant is entitled to an Award without apportionment.

Applicant sustained a prior lumbar spine permanent disability award of 18% based on Hormoz Zahiri's medical report in 2009.

Favours neutral

Established prior award relevant to apportionment analysis.

From the decision · page 6The injury of March 9, 2007, resulted in a Stipulation with Request for Award (case ADJ3679303) for 18% permanent disability to the back. The 18% permanent disability was based a 10% Whole Person Impairment based on the report of Hormoz Zahiri, M.D. using DRE method. The stipulation indicates that the permanent disability in paragraph three is based on a 10% Whole Person Impairment found by the treating physician Dr. Zahiri. The Award was approved on April 9, 2009.

Defendant failed to provide substantial medical evidence on overlap between current and prior lumbar spine injuries.

Favours Applicant prevailed

Failure to meet burden of proof on apportionment under Labor Code 4664(b).

From the decision · page 19The Arbitrator found even if the interrogatory and medical report are admissible the medical report of the Agreed Medical Evaluator is not based on substantial medical evidence, substantial medical evidence is required on the issue of overlap, the defendant has the burden of proof on the issues of apportionment and overlap and defendant has not met their burden of proof on apportionment, and therefore applicant is entitled to an Award without apportionment.

Anti-attribution clause in Labor Code 4663(e) precludes apportionment to prior awards for presumptively compensable injuries like this case.

Favours Applicant prevailed

Legal bar to apportionment in this case.

From the decision · page 73. The Arbitrator found that apportionment pursuant Labor Code § 4664(b) to a prior permanent disability Award to the lumbar spine is precluded by the anti-attribution clause in Labor Code § 4663(e), and therefore the applicant is entitled to an Award without apportionment.

Medical report of Dr. Hamid Mir on apportionment was a mere conclusion without explanation and not substantial evidence.

Favours Applicant prevailed

Did not support defendant's burden of proof on apportionment and overlap.

From the decision · page 19The Arbitrator finds that the medical report of Dr. Mir on the issues of apportionment and overlap is not substantial evidence because it is a mere conclusion and not supported by reasoning and does not contain an explanation of how and why there is overlap between the two injuries.

Defendant's failure to timely obtain a proper supplemental report based on substantial medical evidence contributed to failure to meet burden of proof on apportionment.

Favours Applicant prevailed

Procedural failure affecting outcome on apportionment.

From the decision · page 20If the defendant failed to meet their burden of proof on apportionment, this failure was a result of their actions in not cross-examining the physician and/or making sure the report was substantial evidence or by timely obtaining a proper supplemental report that is based on substantial medical evidence and therefore their failure to meet their burden of proof does not result in unjust judgment as it resulted from defendants failure.

Found 45% permanent disability based on DRE method; medical report on apportionment not substantial evidence due to lack of explanation and reasoning on overlap.

Medical report on apportionment was a mere conclusion without explanation and not substantial evidence; defendant failed burden of proof on overlap and apportionment.

Provided prior medical report forming basis for prior 18% permanent disability award for lumbar spine injury in 2009.

Prior medical report was basis for prior award; relevant for apportionment analysis.

From the decision · page 6The injury of March 9, 2007, resulted in a Stipulation with Request for Award (case ADJ3679303) for 18% permanent disability to the back. The 18% permanent disability was based a 10% Whole Person Impairment based on the report of Hormoz Zahiri, M.D. using DRE method. The stipulation indicates that the permanent disability in paragraph three is based on a 10% Whole Person Impairment found by the treating physician Dr. Zahiri. The Award was approved on April 9, 2009.

Labor Code 4663(e)

Anti-attribution clause in Labor Code 4663(e) precludes apportionment to prior awards for presumptively compensable injuries.

Applied to bar apportionment under Labor Code 4664(b) in this case.

From the decision · page 73. The Arbitrator found that apportionment pursuant Labor Code § 4664(b) to a prior permanent disability Award to the lumbar spine is precluded by the anti-attribution clause in Labor Code § 4663(e), and therefore the applicant is entitled to an Award without apportionment.

Labor Code 4664(b)

Burden of proof on defendant to show overlap and prior award for apportionment under Labor Code 4664(b).

Defendant failed to meet burden of proof on overlap and apportionment.

From the decision · page 77. The Arbitrator found that if apportionment is allowed pursuant to Labor Code § 4664 in this case, the burden of proof is on the defendant is to prove a prior Award and to prove overlap between the present and prior Award. The Arbitrator finds that defendants have met their burden of proof of showing a prior Award, defendants have not met their burden of proof on showing overlap between the present and prior award, therefore, defendants have not met their burden of proof on apportionment pursuant to Labor Code § 4664, the applicant is entitled to an Award without apportionment.

Medical report of Dr. Hamid Mir on apportionment was a mere conclusion without explanation and not substantial evidence.

From the decision · page 19The Arbitrator finds that the medical report of Dr. Mir on the issues of apportionment and overlap is not substantial evidence because it is a mere conclusion and not supported by reasoning and does not contain an explanation of how and why there is overlap between the two injuries.

Defendant failed to meet burden of proof on apportionment and overlap due to lack of substantial evidence and failure to timely obtain proper supplemental report.

From the decision · page 20If the defendant failed to meet their burden of proof on apportionment, this failure was a result of their actions in not cross-examining the physician and/or making sure the report was substantial evidence or by timely obtaining a proper supplemental report that is based on substantial medical evidence and therefore their failure to meet their burden of proof does not result in unjust judgment as it resulted from defendants failure.