It is a defense to a charge of [murder] [manslaughter] that the homicide was justifiable as defined in this instruction.
Homicide is justifiable when committed in the lawful defense of [the slayer] [the slayer's [husband] [wife] [registered domestic partner] [parent] [child] [brother] [sister]] [any person in the slayer's presence or company] when:
1) the slayer reasonably believed that the person slain [or others whom the defendant reasonably believed were acting in concert with the person slain] intended [to commit a felony] [to inflict death or great personal injury];
2) the slayer reasonably believed that there was imminent danger of such harm being accomplished; and
3) the slayer employed such force and means as a reasonably prudent person would use under the same or similar conditions as they reasonably appeared to the slayer, taking into consideration all the facts and circumstances as they appeared to [him] [her], at the time of [and prior to] the incident.
The State has the burden of proving beyond a reasonable doubt that the homicide was not justifiable. If you find that the State has not proved the absence of this defense beyond a reasonable doubt, it will be your duty to return a verdict of not guilty.
The language above are the jury intructions associated with self defense. My belief is that in your scenario you would not be even close to being justified in shooting someone. I would also suggest that if you are armed with a gun that you run if you can before you use your gun. You do not have a duty to retreat but that would be my advice. What if this person in you scenario was mentally ill? or under the influence of something? There is a host of reasons for the behavior you have wrote about that would explain the behavior and would not warrant shooting them.
You can find an excellent discussion regarding your question from the Washington State Supreme Court in the case of STATE v. WALDEN, 131 Wn.2d 469, 932 P.2d 1237 (1997) (http://www.mrsc.org/wa/courts/index_dtSearch.html). In general, the use of force in self-defense must be "reasonable" and the extent of the use of force must be proportional to the exigent circumstances.
[In accordance with the Avvo community guidelines, this communication does not constitute "legal advice", nor does it form an attorney-client relationship.]
I read a lot in gun forums that its better to judged by twelve than carried by six. This may have some truth to it but its really best if neither has to happen. And most of those people saying that have never gone to jail for the rest of their lives and lost their family, job, home, and life over a stupid overreaction.
In this scenario, why are you justified in pulling your gun if he's following you? You have never told him that he can't. There is no law against him following you? And while you may "know" what he is doing, all you really can do is strongly suspect (based of your own biases and prejudices) what he is doing. There are laws against pulling guns out and saying if you don't do what I say I'm going to shoot you.
So your question is can you preemptively act and draw a line the sand. Probably, and almost certainly, not. But it depends. Are you in a dead end alley? Are you an 80 year old woman and he a 20 year old Hells Angel? Is the area well lit? Are there others around who can call for help? Why can't you call for help? Many other questions. The touchstone here, as the other commentators have pointed out, is reasonableness. Is it reasonable for you to do what you did under the circumstances?
And then he crosses the line. Where is the line? Is he two, ten, 21 or 50 feet away? Plus everything else above.
The prosecutor must prove beyond a reasonable doubt that you did not act in self defense, but only if you can claim self defense. People are just allowed to pull guns out and draw lines wherever they please. When this happens, you had best be prepared to bet your life on your actions.
And know this: I say this as a concealed weapons holder, lifetime member of the NRA, and with over two hundred hours of intensive handgun/shotgun/rifle self defense training. Whether you can legally shoot someone will ALWAYS be determined by the law one way or the other. You had best be able to convence many people besides yourself of the lawfulness of your actions. Check out the Armed Citizens Network for some more information.