Authorities as the decision cited them, with how this panel applied each one.
Lab. Code, 3600(a)
An employee bears the burden of proving injury AOE/COE by a preponderance of the evidence.
The Board applied this standard to assess the burden of proof on the applicant.
From the decision · page 4B.
Section 3600(a) provides liability for injuries sustained "arising out of and in the course of
the employment." An employer is liable for workers' compensation benefits "without regard to
negligence." (Lab. Code, § 3600(a).) An employee bears the burden of proving injury AOE/COE
by a preponderance of the evidence. (South Coast Framing, Inc. v. Workers' Comp. Appeals Bd.
(Clark) (2015) 61 Cal.4th 291, 297-298, [80 Cal.Comp.Cases 489]; Lab. Code, § 3600(a),
3202.5.) Whether an employee's injury arose out of and in the course of employment is generally
a question of fact to be determined in light of the particular circumstances of the case. (Wright v.
Beverly Fabrics (2002) 95 Cal.App.4th 346, 353 [67 Cal.Comp.Cases 51].)
South Coast Framing, Inc. v. Workers' Comp. Appeals Bd. (Clark) (2015) 61 Cal.4th 291
Medical evidence that industrial injury was reasonably probable constitutes substantial evidence for a finding of injury AOE/COE.
The Board noted that reasonable probability of industrial injury is sufficient for causation.
From the decision · page 5For the purpose of meeting the causation requirement in a workers' compensation injury
claim, it is sufficient if the work is a contributing cause of the injury. (South Coast Framing, Inc.
(Clark), supra, at pp. 298-299.) "The applicant in a workers' compensation proceeding has the
burden of proving industrial causation by a `reasonable probability.' (citation) That burden
manifestly does not require the applicant to prove causation by scientific certainty." (Rosas v.
Workers' Comp. Appeals Bd. (1993) 16 Cal.App.4th 1692, 1700-1701 [58 Cal.Comp.Cases 313].)
Medical evidence that industrial injury was reasonably probable, although not certain, constitutes
substantial evidence for a finding of injury AOE/COE. (McAllister v. Workers' Comp. Appeals
Bd. (1968) 69 Cal.2d 408, 417 [33 Cal.Comp.Cases 660].)
Peter Kiewit Sons v. Industrial Acc. Com. (1965) 234 Cal.App.2d 831
Expert medical opinion is essential to sustain a finding of injury when the issue is exclusively medical.
The Board emphasized the necessity of expert medical opinion for injury determination.
From the decision · page 5Although the factual issue of the occurrence of the alleged incident is a determination for
the WCJ, the issue of injury is a medical determination, which requires expert medical opinion.
As the Court of Appeal explained in Peter Kiewit Sons v. Industrial Acc. Com. (1965) 234
Cal.App.2d 831, 838 [30 Cal.Comp.Cases 188]: "Where an issue is exclusively a matter of
scientific medical knowledge, expert evidence is essential to sustain a [WCAB] finding; lay
testimony or opinion in support of such a finding does not measure up to the standard of substantial
evidence. Expert testimony is necessary where the truth is occult and can be found only by
resorting to the sciences."