The felony murder rule, adopted by a number of jurisdictions, is a legal doctrine according to which anyone who commits, or is found to be involved in, a serious crime (a felony), during which any person dies, is guilty of murder. (In states with the death penalty, this usually includes capital murder, although there are independent constitutional limitations on the imposition of the death penalty on those guilty of felony murder.) This applies even if one does not personally or directly cause the person's death. For example, a getaway driver for an armed robbery can be convicted of murder if one of the robbers killed someone -- or got killed in some jurisdictions -- in the process of the robbery, even though the driver was not present at and did not expect the killing.

However, the actual situation is not as clear-cut as the above implies. In reality, not all felonious actions will apply in most jurisdictions. To "qualify" for the felony murder rule, the felony must present some degree of danger. If while passing a forged check, the receiver, who happens to be a hemopheliac, gets a paper cut and bleeds to death, most courts will not hold the defendant guilty of murder.

On the other hand, many activities that are inherently very dangerous cannot apply for the felony murder rule. Aggravated assault, for instance, does not. The reason is that virtually all murders result from an assault! (It's hard to cause the death of someone without causing them bodily harm.) But aggravated assault is a felony. Thus if the felony murder rule were to apply in the case of aggravated assault, it would essenitally reduce the culpability requirements carefully set by the legislature for murder to those requirements of assault. For this reason aggravated assault would be said to "merge" with murder.

To counter the common law style interpretations of what does and does not merge with murder (and thus what does not and does qualify for felony murder), many states explicitly list what offenses qualify. The American Law Institute's Model Penal Code lists robbery, rape or forcible deviate sexual intercourse , arson, burglary, kidnapping, and felonious escape.

Other issues also loom. For instance, whose actions can cause the defendant to be guilty of felony murder? There are two schools of thought. One is the agency theory; the other is the proximate cause theory. The former states that only deaths caused by the agents of the crime can result in a felony murder conviction, while the latter holds that any deaths that result from a crime would qualify. As an example of the distinction, take the following hypothetical.

Say John Doe is robbing a bank. John is a bit careless however, and is not paying attention long enough that one of the tellers has a chance to hit the silent alarm. Police arrive, and corner John. Rather than give up nicely, John decides to try to fight his way out, and begins shooting. Officers return fire, and one of them tragically misaims and the bullet strikes and kills a bystander. In this case, jurisdictions that follow the agency theory would hold that John is not guilty of felony murder in the death of the bystander, as the death was immediately caused by the actions of the police, who are not agents of the crime. Jurisdictions following the proximate cause theory however adopt an opinion much closer to a but for relationship: the death would not have occurred but for the commission of the crime, so John is guilty of felony murder.

Note that if John Doe was not alone and was with, say, his wife Jane Doe, if John kills someone (even accidentally) during the comission of the robbery, both John and Jane are guilty of felony murder since they are both agents of crime, and conspired together. Even Joe Shmoe driving around the block in the getaway car would be guilty of felony murder despite the fact that he likely didn't even know that anyone was killed. This is essentially universally held.

Felony murder is typically the same grade of murder as premeditated murder. In many jurisdictions, felony murder is a crime for which the death penalty can be imposed, subject to one of two additional requirements. A person convicted of felony murder cannot be executed unless it is shown that he himself killed, attempted to kill, or intended to kill. For example, three people conspired to commit armed robbery. Two of them went in to the house and committed the robbery, and in the process killed the occupants of the house. The third person sat outside in the getaway car, and he was later convicted of felony murder. But because he himself neither killed, attempted to kill, or intended to kill, he cannot be executed even though he is guilty of felony murder.

On the other hand, a person who is convicted of murder can be executed if it is shown that he was a "major participant" in the murder and showed "extreme indifference to human life." For example, three brothers who broke their father out of prison and went on a crime spree killed a family traveling along a highway. They did so by flagging down their car under the pretense of being distressed motorists, then leading them out into the desert and shooting them execution-style. The father was the one who actually pulled the trigger, but the brothers were present at the killings and could have stopped them. A statewide police manhunt ensured; the father and brothers parted ways, and the father and one of the brothers died of exposure in the desert. The two remaining brothers were later apprehended, and the Supreme Court ultimately ruled that imposing the death penalty on them did not violate the Constitution.