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 Iowa, the felony murder rule is codified in the state's criminal statutes and is a component of the state's homicide laws. Under Iowa law, a person commits felony murder, classified as murder in the first degree, if a death results from the commission of a forcible felony. Forcible felonies in Iowa include crimes such as robbery, burglary, kidnapping, arson, rape, and other violent felonies. This means that if someone is killed during the commission of one of these felonies, all participants in the felony can be charged with first-degree murder, regardless of their level of direct involvement in the actual killing. This includes individuals who may have served as lookouts or getaway drivers. The rule applies even if the death was unintentional or accidental, and it can also apply if a co-felon is killed, for example, by law enforcement during the commission of the crime. The intent behind the felony murder rule is to hold all participants in certain dangerous felonies accountable for any deaths that occur as a result of the felony, reflecting the increased risk of harm associated with such crimes.