Which of the following is a but-for cause test?

• A. But-for cause
• B. Acceleration of result
• C. Intervening cause
• D. Eggshell rule

Answer: (A)

But-for causation asks whether the harm would have occurred if the defendant’s conduct had not happened. If removing the defendant’s actions would have prevented the injury, then those actions are a but-for cause of the harm. This is the standard way to establish actual causation in many tort cases—the defendant’s conduct must be essential to the happening of the harm.

Why this fits: the term itself refers to the necessity of the defendant’s conduct for the injury to occur. If the injury would still have happened anyway, the defendant is not a but-for cause.

The other concepts describe different ideas: acceleration of result focuses on hastening an injury that would occur anyway rather than being the essential cause; an intervening cause can break the chain of causation; the eggshell rule deals with the extent of damages based on the plaintiff’s susceptibility, not with whether the harm would have happened but-for the defendant’s act.