Mental stress claims.
The extraordinary nature of the alleged mental stress is judged according to an objective standard in comparison with contemporary national employment and nonemployment life. Medical causation requires proof that the physical, mental, or emotional disease was medically caused by the mental stress that is the legal cause of the physical, mental, or emotional disease. An employee who alleges a compensable occupational disease involving mental stress bears the burden of proof to establish legal and medical causation by a preponderance of the evidence.