Proximate Cause

In tort or personal injury law, "proximate causation" refers to an act or omission significant enough in the chain of events leading to an injury that the law holds the person liable to the victim(s).

Proximate cause is the primary cause of the injury, but it does not mean that it is the only cause or even the "closest" cause to the accident. Courts have determined that if the accident would not have occurred "but for" the wrongdoer's conduct, that conduct is the legal cause of a victim's injuries.

There is a difference between the actual, direct cause of an accident and proximate cause. That difference is not always easily understood.

Below, our California personal injury attorneys address frequently asked questions about proximate causation and how it may affect your case:

Personal injury law
The concept of proximate cause is extremely important in personal injury cases in determining who is at fault for your injuries.

1. What is proximate causation in an accident?

In California, courts follow the "substantial factor" test to determine proximate cause. A person's actions are the proximate cause of another person's injury when the wrongdoer's actions were a substantial factor in causing the injury. The person's conduct must be a material, or relevant, factor in contributing to the harm.

1.1 What is a substantial factor under California law?

The definition of a substantial factor is defined in the California Civil Jury Instructions, which are guidelines read to a jury before they must make their decision at trial. The jury instructions state1:

A substantial factor in causing harm is a factor that a reasonable person would consider to have contributed to the harm. It must be more than a remote or trivial factor. It does not have to be the only cause of the harm.
Conduct is not a substantial factor in causing harm if the same harm would have occurred without that conduct.

1.2 What is considered conduct in a personal injury claim?

Conduct refers to the acts or failures to act on which a personal injury lawsuit is based. The definition of conduct includes:

  • Intentional conduct which causes injury (Intentional Torts);
  • Negligent conduct which causes injury;
  • Bad acts;
  • Failure to perform a duty imposed by law.

The word "conduct" can mean a wide variety of things, but analyzing how that conduct is connected to the injury is necessary to determine proximate causation.

1.3 What does "but for" causation mean?

When a jury determines that the accident would not have occurred "but for" the conduct of the party being sued (the defendant), this establishes proximate causation. Important to this determination is whether, without that conduct, the accident would have occurred anyway. This question is usually up to the jury to decide, unless the trial happens in front of just the judge. 2

Example: Allen is driving the wrong way down the highway. Becky sees Allen and swerves to avoid being hit. She narrowly misses hitting him head on, but instead crashes into the guardrail, causing serious neck and back injuries. Allen's conduct of driving the wrong way on the highway is the "but for" cause of Becky's injuries. If he had not been driving towards her, she would not have swerved, and she would not have crashed.

The "but for" test has been absorbed into the substantial factor test, but the meaning of the phrase is still important in helping juries determine who is at fault in an accident.

1.4 What is a remote or trivial factor?

Under the "substantial factor" test, a person's conduct cannot be so trivial or disconnected that it is not really the cause of the accident. If the accident would have occurred despite the person's conduct, it is not likely that it will be considered a substantial factor in causing the accident or injury.

If the accident would not have occurred "but for" the conduct, but it is so far removed from the actual cause of the accident, the conduct may be too remote to hold a person liable for the injuries of another.

Example: Ann wakes up 30 minutes late because her alarm clock did not go off because it was defective. Ann drives to work. Laura is driving alongside Ann on the highway, but does not check her side view mirror and drives into Ann's car. Ann loses control and suffers broken bones and a traumatic brain injury.
While Ann would have a claim against Laura, she could not sue the alarm clock company in a defective products lawsuit. Technically, "but for" the defective alarm clock Ann would not have been injured. However, this is too far remote to be considered a substantial factor in causing the harm.

2. What happens when there are multiple causes of an accident?

The California Jury Instructions provide guidance to juries on how to determine liability when multiple people are the cause of an injury. 3

A person's negligence may combine with another factor to cause harm. If you find that the defendant's negligence was a substantial factor in causing the victim's harm, then the defendant is responsible for the harm. The defendant cannot avoid responsibility just because some other person, condition, or event was also a substantial factor in causing the victim's harm.

This instruction only applies in cases of negligence. The rules are different for intentional torts such as assault or battery.

2.1 What does this mean for my case?

If your accident was caused by multiple people, an individual cannot argue that because someone else was also at fault that they should not be liable to you. If his or her actions were a proximate cause of the injuries you suffered he or she will be held responsible for your damages.

When several people are responsible for your injuries, they will be held jointly and severally liable for your economic damages. 4 Joint and several liability means that even though two or more people were determined to have caused your injuries, you can collect the entire economic damage money award from any one of them. Non-economic damages cannot be held jointly and severally among the defendants, but instead, can only be responsible for their relative percentage of liability.

3. Does the harm have to be foreseeable to create liability?

Part of the common law doctrine of proximate cause has dealt with the foreseeability of the harm caused. If the type of harm that was caused was so unlikely to occur that a reasonable person would not foresee the possibility, or the possibility was so remote, he or she may not be liable for the harm caused.

However, simply because the harm was not foreseeable will not necessarily prevent liability. Foreseeability is measured against what a reasonable person would foresee, not what the particular person who caused the accident could foresee. Further, certain California statutes specifically state that liability may attach even when the harm could not have been anticipated. 5

4. What is a superseding cause?

A superseding cause is a new, separate cause that breaks the chain of proximate causation between a person's negligence and the injury at issue in the lawsuit. This new act occurs after the original act. An intervening cause will break the chain of causation and absolve a person of liability only if the cause is a "superseding" cause.

To be superseding, both the conduct and the injury must be unforeseeable. Otherwise, it may be that multiple parties are all responsible for a person's injuries.

Example: Aaron spills gasoline on the pavement while filling his car. Walter walks by and throws a cigarette onto the ground, which hits the gasoline, causing it to ignite. The fire burns Saul who was walking in the area. Aaron can argue that Walter's conduct of throwing the cigarette was a the superseding cause of Saul's injuries. If he is successful in his argument, he will not be held liable for Saul's injuries.
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For questions about filing a personal injury lawsuit, the impacts of proximate causation, or to confidentially discuss your case with one of our skilled California personal injury attorneys, do not hesitate to contact us at the Shouse Law Group.

We have local law offices in and around Los Angeles, San Diego, Orange County, Riverside, San Bernardino, Ventura, San Jose, Oakland, the San Francisco Bay area, and several nearby cities.


Legal References:

  1. California Civil Jury Instructions (CACI) 430. ("As phrased, the definition of 'substantial factor' subsumes the 'but for' test of causation, that is, 'but for' the defendant's conduct, the plaintiff's harm would not have occurred.")
  2. Same as footnote 1. ("The substantial factor standard . . . subsumes the 'but for' test while reaching beyond it to satisfactorily address other situations, such as those involving independent or concurrent causes in fact.")
  3. California Civil Jury Instructions (CACI) 431.
  4. Cal. Civ. Code § 1431; Cal. Civ. Code § 1431.2.
  5. Cal. Civ. Code § 3333. "For the breach of an obligation not arising from contract, the measure of damages . . . is the amount which will compensate for all the detriment proximately caused thereby, whether it could have been anticipated or not."

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