I teach classes on this and related subjects, as well as firearms, defensive tactics, and tactical operations. I also lead & train a High Risk Entry/SWAT Team. I've carried firearms and dealt with these issues professionally for nearly 30 years.
Just for a point of reference, I'll advise that I have been a defendant in a use of force lawsuit, and have testified as a witness (both as arresting officer and as an expert witness) in numerous criminal trials involving the use of force.
It always amuses and somewhat alarms me when I see or hear folks (to include LEO's) talk casually about using deadly force and taking human life, as well as in legal absolutes. No offense to anyone here, but the vast majority of the time, this individual has no experience in these things, and at best is speaking theoretically.
Always remember you have to survive the legal and psychological aftermath as well as the incident, as described above. The following is not a slam on anyone, but an attempt to give a some insight into the realities of using force.
Show me someone who speaks of "Great Bodily Harm" as justification of taking a human life, and I'll show you someone who has never done it, let alone witnessed the legal aftermath.
GBH is a legal term highly subject to interpretation. The poster stated he was not in fear of death, but "worried" about great bodily harm. By making that statement,takes himself out of the realm of justifiable use of deadly force, and squarely in the center of civil & criminal liability if he does. In this instance he would never sell GBH as a justification in court, and the opposing attorney would shred him. If he were to have shot someone then made this statement, he would probably open himself up to a charge of Manslaughter or Negligent Homicide.
Pulling out a CW and brandishing it as a threat is not a good idea, tactically or legally. You have just lost the vital tactical element of surprise (which equates to lag time as your opponent processes your actions, examines his options, and decides what to do next), you stand at least a 50/50 chance of escalating the situation (what do you do now if your opponent isn't afraid/doesn't back down or flee and you aren't justified in shooting him?), and if a physical brawl ensues, you are responsible for any accidental discharge. Best to leave it holstered/concealed, and if you HAVE to use it, draw it and USE IT!
On this subject, anyone with a CCW permit should not only seek out as much documented firearms training as he can, he should also take a defensive tactics course that includes Firearms Retention (how to keep an assailant from disarming you).
Bear in mind that if you use deadly force, you may be charged criminally, and you WILL be sued civilly by someone, be it the victim, his NOK, or a bystander you hit or endangered by stray rounds. It's axiomatic that a fully justifiable shooting will cost you at least $25,000, either to defend yourself or to settle out of court. If you are a citizen and not a LEO, you have no civil legal protection, entity insurance, or legal team if this happens. Your life savings, property, real estate, everything you have is at risk.
Lastly, bear in mind the huge phsychological event that taking a human life is.
Even the most deserving scumbag has a life, hopes, dreams, and NOK who probably love him, and if you kill him, you are directly responsible for taking them away. So being, you better have this right in your mind before you carry a gun, and you better be sure you're not only justified, but that there's no other alternative, if you use it.
In closing...
If you have a CCW permit and carry, get as much documentable training as you can. Practice with your weapon & holster system for optimum proficiency.
Be tactically aware of your environment and people around you. Anticipate trouble and avoid it.
Use visualization technique to run throught "what if" scenarios. See yourself making the right decisions and doing the right things. This is a vital and never ending excercise. Don't underestimate it's value.
Remember there few legal absolutes in the use of deadly force, and that you have to exercise all other reasonable & viable options before employing deadly force. If GBH is your justification, you need to be able to clearly and absolutely be able to articulate WHY YOU WERE UNQUESTIONABLY IN FEAR.
If you do use deadly force, invoke your right to remain silent and consult an attorney BEFORE making ANY statements to ANYONE, not just to LE. Be polite but firm, and assure LE that you will cooperate, but not until you've spoken to an attorney.
Understand and be prepared for probable psychological after effects. Be prepared to attend counseling. See a phsyciatrist or physchologist rather than a counselor, as doctor-patient privilege applies with them, and may not with a licensed counselor.
Normally I would charge for a mini-seminar like this, but this one's free in the interest of public and brother shooter's service. Hope it provides a little food for thought...