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 Wyoming, the felony murder rule is codified in state statutes and is a component of the state's criminal law framework. Under Wyoming law, an individual can be charged with felony murder if they or an accomplice cause the death of another person while committing, attempting to commit, or fleeing from the commission of a violent felony. The list of predicate felonies typically includes crimes such as robbery, burglary, kidnapping, sexual assault, arson, and others that are inherently dangerous to human life. This means that all participants in such a felony can be held equally liable for a death that occurs during the commission of the crime, regardless of who actually caused the death. This includes situations where an accomplice serves as a lookout or getaway driver. The rule applies even if the death was unintentional or if it was a co-felon who was killed, for example, by law enforcement during the crime. The intent behind the felony murder rule is to deter individuals from engaging in felonies that could foreseeably result in loss of life by holding them strictly responsible for any resulting deaths.