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 New Mexico, the felony murder rule is codified in state law and holds that an individual can be charged with first-degree murder if a killing occurs during the commission or attempted commission of certain felonies, regardless of intent to kill. The underlying felonies typically include violent crimes such as robbery, burglary, rape, kidnapping, and arson, among others. This means that all participants in the felony can be held equally liable for a death that occurs during the crime, even if they did not directly cause the death. This includes lookouts, getaway drivers, and other accomplices. The rule applies whether the death was accidental or intentional, and even if the deceased is a co-felon killed, for example, by law enforcement during the commission of the crime. New Mexico's application of the felony murder rule reflects the state's interest in deterring individuals from participating in felonies that could foreseeably result in loss of life.