Proximate Causation in California Law

What is Proximate Causation?

California follows substantial factor causation. California Civil Jury Instruction 430 describes substantial factor causation as follows: “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.”

Thus, for being liable in a California personal injury case, defendant’s conduct must have substantially contributed to the harm such that in case the defendant didn’t act as he did, the harm wouldn’t have occurred.

What Is “Conduct” Considered to Be?

In the context of causation, conduct refers to the illegal acts or omissions, on which a claim of legal fault is based, such as product defect, negligence, dangerous condition of public property, or breach of contract.

What is a “Substantial Factor” Considered to Be?

Defendant’s contributing conduct must be more than a trivial or remote factor. The defendant’s conduct which proximately, directly, and substantially caused injuries to the plaintiff must have been intentional, negligent, or violate.

For example, in case the defendant’s innocent cough has startled a plaintiff into falling and injuring himself, the plaintiff can’t sue the defendant for personal injury unless the defendant’s conduct was intentional for the purpose of making the plaintiff startle and fall.

Defendant’s conduct can’t be considered a substantial factor in causing the injury to the plaintiff in case the same injury would have occurred without that conduct. Proximate and direct causation requires that the defendant set off a reasonably predictable series of events that lead to the plaintiff’s injuries.

Multiple Causes Contributing to Proximate Causation

Defendant’s negligence can combine with another factor to cause injury to the plaintiff. In case the defendant’s negligence was a substantial factor in causing injury to the plaintiff, then the defendant is responsible for the injury.

The defendant cannot avoid legal responsibility just because some other condition, person, or event was also a substantial factor in causing the injury to the plaintiff.

Third-Party Conduct as Superseding Cause

In case the defendant claims that the injuries were caused to the plaintiff as a result of another person’s misconduct he must prove all of the following:

• Another person’s conduct occurred after the defendant’s conduct.
• A reasonable person would consider that conduct a highly unusual or an extraordinary response to the situation.
• The defendant did not know and had no reason to expect that another person would act in a such illegal or negligent way.
• The cause injury from another person’s conduct was different from an injury that could have been reasonably expected from the defendant’s conduct.