Joseph Gerdon v. Con Paulos, Inc., 372 P.3d 390

On June 13, 2008 Joseph Gerdon was seriously injured in a work-related motor-vehicle accident and the Industrial Commission previously found multiple physical injuries and awarded benefits.
Gerdon sought additional benefits for a compensable psychological injury (depression); a referee and then the Commission concluded he failed to prove entitlement.
Gerdon’s expert, Dr. Daniel Marsh (physiatrist/pain specialist), testified the work injury and chronic pain were the predominant cause of his depression.
Respondents’ expert, Dr. Robert Calhoun (clinical psychologist), after testing and multiple evaluations, concluded the depression was about 50% due to the work-related pain and 50% due to preexisting personality/dysthymic factors and life stressors.
The referee and Commission found Dr. Calhoun more credible, discounted Dr. Marsh for using an improper “take claimant as found” approach and for failing to evaluate preexisting psychological factors, and denied psychological-care benefits.
The Court reviewed only legal questions and whether the Commission’s factual findings were supported by substantial and competent evidence and affirmed the Commission’s order.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether Gerdon proved the industrial accident was the "predominant cause" (I.C. § 72-451(3)) of his depression	Gerdon: accident predominates; Dr. Marsh: chronic pain from the work injury is the predominant cause; family/friends testified no pre-accident hostility/depression	Respondents: Dr. Calhoun’s testing and interviews show preexisting personality/dysthymic traits and other stressors contributing ~50% so the accident is not predominant	Court: Affirmed—Commission permissibly credited Dr. Calhoun; substantial competent evidence supports finding that Gerdon failed to prove the accident was the predominant cause; appellate court will not reweigh credibility of experts

Tarbet v. J.R. Simplot Co., 151 Idaho 755, 264 P.3d 394 (2011) (appellate review of Industrial Commission in workers’ compensation is limited to questions of law and defers to Commission factual findings supported by substantial evidence)
Anderson v. Harper’s Inc., 143 Idaho 193, 141 P.3d 1062 (2006) (claimant bears burden to prove causation to a reasonable degree of medical probability; Commission may not find causation without medical expert opinion)
Mazzone v. Texas Roadhouse, Inc., 154 Idaho 760, 302 P.3d 718 (2013) (predominant-cause standard requires comparing the accident against all other causes combined when evaluating compensability of psychological injuries)