§ 14.02 Actual Cause (or "Factual Cause")

§ 14.02 Actual Cause (or "Factual Cause")

[A] "But-For" ("Sine Qua Non") Test

Causation analysis is divisible into two parts: "actual cause" (also called "factual cause" or "cause-in-fact") and "proximate cause" (or "legal cause"). The first causal issue that might be determined is that of "actual cause." That is, there can be no criminal liability for resulting social harm "unless it can be shown that the defendant's conduct was a cause-in-fact of the prohibited result."¹⁵ In order to make this determination, courts traditionally apply the "but-for" or "sine qua non" test, i.e., " 'that the harm would not have occurred' in the absence of—that is, but for—the defendant's conduct."¹⁶ This test may also be stated more fully as follows: "But for D's voluntary act(s),¹⁷ would the social harm have occurred when it did?" If the answer is "yes"—the social harm would have occurred when it did even if D had not acted—then D's conduct was not the actual cause of the harm. If the answer to the question is "no"—the social harm would not have occurred when it did in the absence of D's voluntary conduct—D is an actual cause of the result.

The but-for test serves a limited, but essential, purpose. It functions to exclude certain forces, including human ones, from potential causal responsibility for ensuing harm. That is, subject to one controversial and very limited exception,¹⁸ D cannot be held criminally responsible for a result unless the prosecution proves beyond a reasonable doubt that D is a (not necessarily "the"¹⁹) but-for cause of the harm.

The fact that D's conduct is determined to be an actual cause of a result does not mean that he will be held criminally responsible for the harm. To be guilty, D must have also acted with the requisite mens rea,²⁰ and he must also be the proximate cause of the social harm, the latter issue of which is considered in § 14.03.

[B] "Causes" versus "Conditions"

D pulls the trigger of a gun, and a bullet is propelled from the gun into V's chest, causing V's death. Common sense tells us that D was the cause of the death: But for D's voluntary act of pulling the trigger of the gun, V would not have died when he did.

In fact, however, we might try to say that there are additional "actual causes" of V's death. For example, V would not have died but for the fact that his heart muscle was too weak to withstand the intrusion of the bullet. Other causes of the death might be found in certain principles of physics that explain how and why the pulling of the trigger results in a bullet moving at a fast rate of speed. However, the law will either ignore these latter "causes" or identify them more realistically as necessary "conditions" for the harm to occur. Although conditions may technically meet the sine qua non test of causation, their exclusion from the latter category is consistent with a commonsense view of the issue.²¹

In determining causation, people focus on what is interesting in an event. They focus on the abnormal, the matters that seem out of the ordinary.²² "Conditions" are normal events or circumstances that, although necessary for the result to occur, do not positively contribute to it. D's firing of the gun is the act that is interesting and out of the ordinary. It is D's conduct, and not the basic laws of physics or the structure of V's heart (or, for that matter, that it was light enough that day for D to see V so he could kill him) that affirmatively contributed to the death.

[C] Special "Actual Cause" Problems

[1] Confusing "Causation" with "Mens Rea"

The common law treats "actual causation" and "mens rea" as independent concepts, each of which must be proven in a criminal prosecution. Frequently, however, this point is forgotten, resulting in improper analysis.

[a] Causation without Mens Rea

D has a minor argument with her husband, V. V, upset about the argument, decides to leave the house. He walks across the street. As he does, he is struck and killed by an automobile driven by X. Is D an actual cause of V's death? Based on the facts just described, the answer is "yes": But for D having the argument with V, V would not have crossed the street at that moment and, therefore, would not have been struck and killed by X.

It does not necessarily follow, however, that D may successfully be convicted of a crime pertaining to V's death. First, D was not the sole cause of the harm. X's conduct was another cause. So, too, was V's decision to leave the house and cross the street. "Actual cause," it will be remembered, serves only to eliminate candidates for responsibility; it does not resolve the matter of ultimate causal responsibility, which awaits proximate causation analysis. Second, and more immediately to the point, the facts do not suggest that D possessed a culpable state of mind—any mens rea—regarding V's death. Thus, this is a case of but-for causation without a mens rea.

[b] Mens Rea without Causation

Just as a person may be an actual cause of resulting harm without having a mens rea, it is also possible to possess a culpable state of mind without being the actual cause of the harm. For example, suppose that D1, ...