Apportionment and Substantial Medical Evidence: Burden of Proof in Workers’ Compensation

Apportionment is one of the most litigated and closely scrutinized issues in California workers' compensation today. Once an injured worker establishes that a permanent impairment exists, the burden shifts to the defense to prove that a portion of that impairment is properly apportioned to non-industrial causes. John Ajayi, Ajayi Law Group, walks attorneys through this framework from the ground up, covering what substantial medical evidence actually requires, how apportionment opinions are evaluated, and where defense medical evidence commonly falls short. The rules are concrete, but the process is easy to get wrong, and attendees will leave with practical strategies for challenging flawed apportionment findings and rebutting defense evidence that does not meet the legal threshold.