shoot first.
In general, pointing a gun at someone is only justified when SHOOTING that person would be justified. Trespass does not rise to that level. Pointing a gun at someone without SERIOUS reason is proably going to result in jail.
I am pretty positive you can.
He was walking down a street and found a gun and he was pointing it at someone.
Pointing at the target.
No. In all United States, pointing a fire-arm at someone in a non-self defense situation unless you are a law enforcement officer is strictly illegal.
They would most likely be charged with assault. Penalty (if convicted) would depend on the judge.
Taking Aim
Actually, it is legal to kill a man when he is pointing a gun at you because it is considered self defense. You may be sued but it is considered legal.
they should be pointing down in the water
Your question is rather vague. If you mean what should a physician do if someone OWNS a gun- I would ask why they should do anything. Owning a gun is not an illness, and is a right guaranteed to Americans. About 1/3rd of he households in the US own at least one gun- and I know several doctors that own guns.
By pointing the barrel at the bird's head
Pray and duck