Legal Cause Law and Legal Definition

Legal cause is the term used in personal injury law, which refers to that which caused a plaintiff's injury, leading him or her to seek a remedy, or compensation from the court. It is known as proximate cause or it is the cause of an effect. The plaintiff's case assumes that this proximate or legal cause is the primary event or circumstance that led to the injury, even though it may not necessarily be the direct cause.

In essence, the legal/proximate cause is that event or condition that produces a particular, predictable consequence without the intervention of any event or condition that may have occurred independently and could not have been foreseen.

To determine the legal cause, the courts use "but for" test - technically known as the sine qua non rule. This is the question of whether or not the plaintiff's injury would have occurred without negligence on the part of the defendant. In some jurisdictions a "substantial factor" formula is applied. The court considers if the defendant's actions or conduct was the primary factor in causing the injury.