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 Arizona, the felony murder rule is codified in the Arizona Revised Statutes under Section 13-1105. This rule holds that a person can be charged with first-degree murder if they, or an accomplice, kill someone, even unintentionally, during the commission of, or flight from, certain felonies specified by the statute. These felonies include, but are not limited to, sexual assault, robbery, burglary, arson, kidnapping, and escape. The rule applies regardless of whether the death was accidental or intentional, and it can implicate all participants in the felony, not just the individual who directly caused the death. This means that accomplices such as lookouts or getaway drivers can face murder charges if a death occurs during the commission of a qualifying felony, even if there was no plan to kill anyone. The felony murder rule in Arizona reflects the state's interest in deterring individuals from engaging in felonies that create a high risk of death.