Injuries covered

(a) If an employee suffers personal injury either by accident arising out of and in the course of the employment or by disease proximately caused by or resulting from the nature of the employment, the employee's employer or the special compensation fund shall pay compensation to the employee or the employee's dependents as provided in this chapter. Accident arising out of and in the course of the employment includes the wilful act of a third person directed against an employee because of the employee's employment. (b) No compensation shall be allowed for an injury incurred by an employee by the employee's wilful intention to injure oneself or another by actively engaging in any unprovoked non-work related physical altercation other than in self-defense, or by the employee's intoxication. (c) A claim for mental stress resulting solely from disciplinary action taken in good faith by the employer shall not be allowed; provided that if a collective bargaining agreement or other employment agreement specifies a different standard than good faith for disciplinary actions, the standards set in the collective bargaining agreement or other employment agreement shall be applied in lieu of the good faith standard. For purposes of this subsection, the standards set in the collective bargaining agreement or other employment agreement shall be applied in any proceeding before the department, the appellate board, and the appellate courts.