What is a felon?
Suppose I see someone possessing a machinegun or a firearm with an altered, changed, removed or obliterated manufacturer's number. I tell them that I am arresting them for a felony. They run. They run forever. I can just shoot him in the back, right?
When is a felon not a felon?
"A private person in fresh pursuit of one who has committed a felony may arrest without a warrant. And in Pennsylvania we have always followed the common law rule that if the felon flees and his arrest cannot be effected without killing him, the killing is justified. We hasten to note that before the use of deadly force is justified the private person must be in fresh pursuit of the felon and also must give notice of his purpose to arrest for the felony if the attending circumstances are themselves insufficient to warn the felon of the intention of the pursuing party to arrest him.
The common law principle that a killing necessary to prevent the escape of a felon is justifiable developed at a time when the distinction between felony and misdemeanor was very different than it is today. Statutory expansion of the class of felonies has made the common law rule manifestly inadequate for modern law.2 Hence, the need for a change or limitation in the rule is indicated. We therefore hold that from this date forward the use of deadly force by a private person in order to prevent the escape of one who has committed a felony or has joined or assisted in the commission of a felony is justified only if the felony committed is treason, murder, voluntary manslaughter, mayhem, arson, robbery, common law rape, common law burglary, kidnapping, assault with intent to murder, rape or rob, or a felony which normally causes or threatens death or great bodily harm. We also note that for the use of deadly force to be justified it remains absolutely essential, as before, that one of the enumerated felonies has been committed and that the person against whom the force is used is the one who committed it or joined or assisted in committing it. If the private citizen acts on suspicion that such a felony has been committed, he acts at his own peril. For the homicide to be justifiable, it must be established that his suspicion was correct."
Commonwealth v. Chermansky, 430 Pa. 170, 173-174 (Pa. 1968) (citations and footnotes omitted).
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