Authorities as the decision cited them, with how this panel applied each one.
Escobedo v. Marshalls (2005) 70 Cal.Comp.Cases 604, 621 (Appeals Bd. en banc)
A medical opinion must be framed in terms of reasonable medical probability, not be speculative, and be based on pertinent facts and adequate examination and history to constitute substantial evidence.
The WCJ applied this standard to reject the applicant's QME's opinion on temporary disability as speculative and unsupported by substantial evidence.
From the decision · page 8Decisions of the WCJ and the Workers' Compensation Appeals Board must be supported
by substantial evidence. (Lab. Code, § 5903, 5952(d); Lamb v. Workmen's Comp. Appeals Bd.
(1974) 11 Cal.3d 274 [39 Cal.Comp.Cases 310]; Garza v. Workmen's Comp. Appeals Bd. (1970)
3 Cal.3d 312 [35 Cal.Comp.Cases 500]; LeVesque v. Workmen's Comp. Appeals Bd. (1970) 1
Cal.3d 627 [35 Cal.Comp.Cases 16].) To constitute substantial evidence "a medical opinion must
be framed in terms of reasonable medical probability, it must not be speculative, it must be based
on pertinent facts and on an adequate examination and history, and it must set forth reasoning in
support of its conclusions." (Escobedo v. Marshalls (2005) 70 Cal.Comp.Cases 604, 621 (Appeals
Board en banc).) Not all expert medical opinion constitutes substantial evidence. (Hegglin v.
Workmen's Comp. Appeals Bd. (1971) 4 Cal.3d 162 [36 Cal.Comp.Cases 93, 97]; Place v.
Workmen's Comp. Appeals Bd. (1970) 3 Cal.3d 372, 378-379 [35 Cal.Comp.Cases 525].) To
constitute substantial evidence, a medical opinion must be predicated on reasonable medical
Escobedo v. Marshalls (2005) 70 Cal.Comp.Cases 604, 613 (Appeals Bd. en banc)
The burden of proof for apportionment to nonindustrial factors lies with the defendant, and the WCJ may choose among conflicting medical reports to rely on the most persuasive.
The WCJ applied this standard to find defendant did not meet burden to prove apportionment beyond 5% to a prior injury.
From the decision · page 7Moreover, while applicant bears the burden of establishing the approximate percentage of
permanent disability caused by the industrial injury, it is defendant that bears the burden of
establishing the approximate percentage of permanent disability caused by factors other than the
industrial injury. (Escobedo v. Marshalls (2005) 70 Cal.Comp.Cases 604, 613 (Appeals Bd. en
banc).) In addition, the WCJ and the Appeals Board are empowered to choose among conflicting
medical and vocational reports and rely on that which is deemed most persuasive. (Jones v.
Workmen's Comp. Appeals Bd. (1968) 68 Cal.2d 476 [33 Cal.Comp.Cases 221].)
Peter Kiewit Sons v. Industrial Acci. Com. (McLaughlin) (1965) 234 Cal.App.2d 831
Expert medical opinion is generally required to establish causation and compensability of back injuries, as lay judgment is insufficient.
The WCJ relied on expert medical opinion to determine the date of injury and compensability of cumulative trauma injury.
From the decision · page 6four years. Despite applicant describing similar low back complaints arising out of all three
employments, the IAC assessed liability to the terminal employer alone. In granting review of the
IAC decision, however, the Court of Appeal found "[t]hat issue may run a gamut from the blatantly
obvious to the scientifically obscure," and that expert testimony would be necessary. "Back
disabilities in particular shout loudly for expert advice... [i]n a field which forces the experts into
hypothesis, unaided lay judgment amounts to nothing more than speculation." (Id. at pp. 839-840.)
Accordingly, "the medical cause of an ailment is usually a scientific question, requiring a judgment
based upon scientific knowledge and inaccessible to the unguided rudimentary capacities of lay
arbiters." (Peter Kiewit Sons v. Industrial Acci. Com. (McLaughlin) (1965) 234 Cal.App.2d 831,
839 [30 Cal.Comp.Cases 188].)