Proximate Cause: A Crucial Element of Vehicular Homicide

One of the biggest questions to answer when someone is charged with vehicular homicide in Washington state is whether the defendant’s conduct was the proximate cause of the fatality. This is arguably the most heavily litigated element of the charge, as causation can be very complicated. Proximate cause establishes a requirement that a defendant’s actions be directly linked with the resulting harm. In the case of vehicular homicide, the element states “that the injured person died within three years as a proximate result of the injuries.” WPIC 90.02(4) (Wash. Pattern Jury Instr. Crim. 2024). To understand this element further, we need to look to the definition of proximate cause, as it is defined in Washington Pattern Jury Instruction 25.02:

To constitute [murder] [manslaughter] [homicide by abuse] [or] [controlled substance homicide], there must be a causal connection between the criminal conduct of a defendant and the death of a human being such that the defendant’s [act] [or] [omission] was a proximate cause of the resulting death.

The term “proximate cause” means a cause which, in a direct sequence, unbroken by any new independent cause, produces the death, and without which the death would not have happened.

[There may be more than one proximate cause of a death.]

WPIC 25.02 (Wash. Pattern Jury Instr. Crim. 2024).

This means that if the State can show that a strong enough chain exists between the defendant’s conduct and the events leading to a death, the defendant could be on the hook for vehicular homicide and held criminally liable. However, this chain isn’t unbreakable. Certain circumstances, such as an independent, unforeseeable superseding act can interrupt the chain and therefore the state’s ability to prove all elements of the charge.

The Two-Part Test

First appearing in 1985 Washington Supreme Court ruling Hartley v. State, a two-part test is well-established to determine proximate cause. This test consists of

1. cause in fact (“but-for” causation), and
2. legal cause

The but-for causation answers the question: “Would the harm have occurred but for the defendant’s conduct?” If the harm would have happened regardless of the defendant’s actions, the but-for causation test will fail. Courts in Washington apply this test to the unique facts presented to them in cases of vehicular homicide, seeking to answer whether the defendant’s actions set the chain of events directly in motion.

The second part of the two-part test is legal cause. Legal cause is a bit more complex and deals with responsibility and foreseeability. A superseding event that breaks the chain of causation will interrupt legal cause and the defendant should not be held responsible under the law. Washington case State v. Leech was brought before the Supreme Court in 1990, with the court addressing foreseeability directly as it relates to proximate cause. This decision cemented the two-part test for proximate cause into criminal law and held that criminal liability requires proof of both cause in fact and legal cause.

Past case law in our state addressing foreseeability have greatly narrowed what is considered unforeseeable. Our Supreme court held in the 2019 case of State v. Frahm that the secondary crash was a foreseeable event following that collision, upholding that the defendant was the legal cause of the resulting death. This doesn’t mean, however, that it’s not possible for a secondary crash to break the chain, especially if it is independent from the initial crash. The specific set of facts and circumstances matter.

Superseding Causes

So, what does count as a superseding cause? It can get complicated when we’re looking at unique sets of facts from real-life circumstances, and this is exactly where we step in to litigate. Superseding cause is defined as a new independent cause that breaks the chain of proximate causation between a defendant’s negligence and an injury event. WPI 15.05 (Wash. Pattern Jury Instr. Civ. 2022). Some examples of superseding causes include:

• Gross negligence during medical treatment of the injured individual, enough that the negligence becomes the cause of death in itself
• A second collision from a third party that is unrelated to the first
• An unexpected event occurring, such as a tree falling on someone

Across all examples of superseding causes is the pattern that it must be independent of the defendant’s conduct, unforeseeable, and the cause of the victim’s death. When such an action exists, proximate cause can be broken, shifting responsibility away from the defendant.

As your legal representation, we will fight for you by going down every possible avenue to provide the most comprehensive defense possible. If you have been charged with vehicular homicide, call our office at (360) 419-0809 to set up a consultation.