Discuss when force in self-defense or the defense of another may not be used...Please give examples to support your answer.
Generally agreed with the above answer. Typically, (and it varies from state to state, and deals mostly with state laws since burglary, robbery and murder are state crimes) there has to be a reasonable belief that your life or safety or that of your family was threatened. The perpetrator may not even have a weapon, but could you reasonably believe they did, and that they intended to use it.
One of the reasons why self defense is easier to prove if the act happened inside your own home is that a criminal is statistically much more likely to use violence inside a home than outside, where they are more likely to flee. Important to note, there is no self defense in the protection of property, only human life. This includes animals. So a neighbor shoots your dog in your backyard, it's not self defense to shoot the neighbor, unless the shot fired at the dog was in your direction too, whereby it would be reasonable to believe it was intended for you. It's complicated law.
The general rule of thumb is that force in self-defense must be proportional to the harm that one believes one may potentially be facing. In other words, you have to use only as much force as is proportional to the danger.]
In other words, you may not shoot someone because you think they are going to throw an egg at your house.
In addition, the threat has to be "clear and present" as the saying goes. You cannot use force unless you have a good reason to believe that something bad is imminent. You are not allowed preemptive strikes based only on what "might" happen.