The felony murder rule is a legal doctrine that expands the definition of murder and makes criminal accomplices (including a lookout or getaway driver) as responsible for a death that occurs in the course of a dangerous felony crime as the person who directly caused the death by pulling the trigger of a gun, stabbing the victim with a knife, strangling the victim, or otherwise causing the victim’s death. Examples of dangerous felony crimes that implicate the felony murder rule include robbery, burglary, rape, aggravated kidnapping, carjacking, and arson.

When the felony murder rule applies, it may make a criminal accomplice liable for murder even if the criminals had agreed that no one would be killed in the course of the crime, and even if it is a fellow criminal who is killed in the course of the crime—such as when a police officer or security guard shoots a bank robber—which may result in all other accomplices to the crime being charged with murder.

In many states the felony murder rule—and any distinctions between the culpability of accomplices and principals to a crime—are located in the state’s statutes—often in the penal or criminal code.

In Pennsylvania, the felony murder rule is codified in the state's criminal statutes and is a significant component of its criminal justice system. Under Pennsylvania law, an individual can be charged with murder if a death occurs during the commission of a felony, even if the individual did not directly cause the death. This means that accomplices to the felony, such as lookouts or getaway drivers, can be held as responsible for a resulting death as the person who actually commits the lethal act. The rule applies to a list of specified felonies, which typically include serious crimes like robbery, burglary, rape, kidnapping, and arson. The intent to kill is not a necessary element for a felony murder charge in Pennsylvania; the mere fact that a death occurred during the commission of a dangerous felony can be sufficient for a murder charge. This doctrine aims to deter individuals from participating in felonies that could foreseeably lead to loss of life. It's important to note that the specifics of the felony murder rule can vary, and the application of the rule can be complex, often requiring the expertise of an attorney to navigate the legal implications.