LAW 511-002 – Torts I

Cause in Fact


Causation in fact is generally determined by the "but for" test.

But For Test

Causation exists when the damage more likely than not would not have occurred but for the defendant's actions.

In statistical evidence, the risk of the harm occurring must have more than doubled.

Substantial factor test applies in "loss of a chance" cases in medical malpractice, based on the jurisdiction.

In cases where two or more actively operating forces, only one of which the defendant was responsible for, combine to bring about the harm, the "substantial factor" test applies instead.

Substantial Factor

Under the "substantial factor" test, causation is determined by whether or not the defendant's act was a "substantial factor" in causing the harm.

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.

For hazardous chemical cases, to be a substantial factor requires "evidence of exposure to a specific product on a regular basis over some extended period of time in proximity to where the plaintiff actually worked."

When two or more causes combine to cause an injury, the defendant is a cause in fact if the defendant's conduct was a substantial factor in causing the injury.

Market Share Liability

When a group of defendants produce a substantial share of the market share of a drug, they may be held liable for harms resulting therefrom for their approximate portion of market share when the specific manufacturer is unknown. Sindell.

This usually only applies to DES cases.