In criminal law, which test is commonly used to establish causation between a defendant's act and the resulting harm?

• A. Proximate cause
• B. But-for test
• C. Legal causation
• D. Foreseeability

Answer: (B)

The key idea is determining factual causation—whether the defendant’s act was a necessary condition for the harm. The but-for test asks: would the harm have occurred if the defendant had not done the act? If the answer is yes, then the act is not the cause in fact; if the answer is no, the act is a factual cause. This is the starting point for liability, because without a but-for link, there’s no causal basis to attribute the harm to the defendant.

Proximate or legal causation and related ideas like foreseeability come into play after factual causation is established, to decide whether the link is strong enough to attach liability under the law. They consider whether other factors or remote consequences break the liability chain or render the result too remote or unforeseeable. But-for causation is the basic test used to identify the actual cause in fact.