People have a variety of different views on when it is okay to kill and most people have certain standard they set for humans and a completely different one for other animals.
Although it may be hard for most people, if an animal is in pain and suffering, they will have it put down to end its suffering. But when it comes to our own kind, the majority of people would rather keep the person alive by use of machine, rather than let them die peacefully or even take their own life to end the suffering. Most of the time the decision to keep living is not made by the person in pain, but the people around them, who would rather keep the person suffering rather than putting themselves through the pain of losing someone close to them. This is a selfish and often-subconscious decision we make because we tend to put our own wants and needs before that of other peoples.
A perfect example of keeping someone alive when they don't want to be is the example of Nancy Crick shown in Peter Singer's documentary, who wanted to end her own life in a peaceful way because she believed she had reached the point where her life was done and she was no longer living.
Nancy wanted her family present when she drank the cocktail of drugs, but that wasn't possible because the law says it is not illegal to commit suicide, but it is illegal to have someone present at the time and that person may be arrested for assisting in suicide. In this particular case it is the law that is being cruel to the person in suffering, not the people that are close to her.
I believe that in cases such as these, the person should...