Workers’ compensation can be a complex subject, especially when it involves altercations in the workplace. At Franco Muñoz Law Firm, we are dedicated to representing injured workers and ensuring they understand their rights and the possible defenses in their cases, including initial physical aggressor defense in workers’ compensation. In this blog post, we will discuss the initial physical aggressor defense under Labor Code § 3600(a)(7).

What is the Initial Physical Aggressor Defense?
Labor Code § 3600(a)(7) establishes that a claim is not compensable when the injury arises “out of an altercation in which the injured employee is the initial physical aggressor.” This defense embodies the legislative intent to exclude from compensation those who introduce violence into the workplace, a crucial aspect of initial physical aggressor defense in workers’ compensation cases.
Defining Prohibited Behaviors
The behaviors barred under this statute were defined in the seminal case of Mathews v. WCAB (1972) 6 Cal. 3d 719. The Supreme Court explained that former LC 3600(g), now LC 3600(a)(7), applies when two conditions are present for initial physical aggressor defense in workers’ compensation to be considered:
- The injury must “arise out of an altercation.”
- The injured employee must be the “initial physical aggressor” in the altercation.
An injury arises out of an altercation if it results from an exchange between two or more persons in an atmosphere of animosity and a willingness to inflict bodily harm. This is different from “horseplay” or “skylarking,” which do not involve animosity, even though they can result in bodily harm.
Determining the Initial Physical Aggressor
The Supreme Court in Mathews clarified that battery is not necessary for one to be deemed the initial physical aggressor. Throwing the first punch does not necessarily make a person the initial physical aggressor. Instead, the initial physical aggressor is the person who first engages in physical conduct that places their opponent in reasonable fear of bodily harm. This could include clenching a fist or aiming a gun, not just physical actions like punching.
To determine who the initial physical aggressor is, it must be established:
- Whether a person engaged in a physical act.
- Whether that physical act placed the opponent in fear of reasonable bodily harm.
Case Study: Nosce v. United Building Contractors Inc.
In the case of Nosce v. United Building Contractors Inc., 2024 Cal. Wrk. Comp. P.D. LEXIS 53, the WCAB upheld a decision that the applicant’s injury was not barred by the initial physical aggressor defense under LC 3600(a)(7). This illustrates how complex initial physical aggressor defense in workers’ compensation cases can be. The applicant, a less experienced roofer, made a mistake and was ordered off the roof by a co-worker. The co-worker claimed the applicant breached his personal space, causing fear of bodily harm, while the applicant testified that the co-worker approached and punched him first.
The WCJ and the WCAB found the applicant more credible, partly based on their physical descriptions and an investigative report from the sheriffâs office. The applicant was shorter and heavier, described as “unfit,” while the co-worker was muscular and fit. The WCJ did not believe the co-worker was afraid of the applicant.
Burden of Proof
The burden of proof in altercation cases rests with the employer, who must show that the applicant first engaged in physical conduct that a reasonable person would perceive as a real, present threat of bodily harm. Employers denying a claim based on LC 3600(a)(7) must be prepared to present testimony, witnesses, or video evidence to establish that the applicant was the initial physical aggressor. Ultimately, it often comes down to the credibility of the witnesses and how strong the initial physical aggressor defense in workers’ compensation is in the specific situation.
Understanding the initial physical aggressor defense is crucial for both employers and employees in workers’ compensation cases. At Franco Muñoz Law Firm, we are here to guide you through these complexities and ensure your rights are protected. If you have been injured at work, contact us today for a free consultation.







