Proximate cause

In the law, a proximate cause is an event sufficiently related to a legally recognizable injury to be held to be the cause of that injury. There are two types of causation in the law: cause-in-fact, and proximate (or legal) cause. Cause-in-fact is determined by the "but for" test: But for the action, the result would not have happened. For example, but for running the red light, the collision would not have occurred. For an act to cause a harm, both tests must be met; proximate cause is a legal limitation on cause-in-fact.

The formal Latin term for "but for" (cause-in-fact) causation, is sine qua non causation.

But-for test

A few circumstances exist where the "but for" test is complicated, or the test is ineffective. The primary examples are: