Just to cover some definitions: a felony is a serious crime usually punishable by more than one year in prison.  Murder is the intentional killing of another human being without justification.

The felony murder rule provides that someone may be guilty of murder under two circumstances where he would otherwise not be guilty of murder:

1. If a person kills someone while committing a violent felony.

2. If a person participates with someone else to commit a violent felony and someone is killed as a result of the crime.

For example, let’s say David commits the serious and violent crime of armed robbery.  He accidentally shoots the victim and kills him.  Normally, killing someone by accident is not murder.  However, the felony murder rule would provide that David is guilty of murder because he killed the victim while committing  the violent felony.

Now let’s say Davida is assisting David with the armed robbery by acting as a lookout.  She didn’t pull the trigger to kill the victim but may also be guilty of murder because she was a participant in the crime.

Keep in mind that different states have different versions of the felony murder rule and federal law has its own definition.  A few states do not have the felony murder rule.