In general, negligent manslaughter is when someone is killed through the gross negligence of another. The defendant doesn't intend to kill someone, but acts extremely carelessly and someone gets killed. For instance, if a drunk driver kills someone on the road, he or she could be charged with negligent manslaughter. Or if a couple of guys are playing with a gun they know is loaded, jokingly pointing it at each other as a game, and the gun goes off killing one of them, the accident could be considered negligent manslaughter. Whether someone will be charged with negligent manslaughter depends on the definition set by state laws, and sometimes the prosecuting attorney may have some discretion in how to charge the faulty party after a fatal accident, depending on the facts of the case.