Individuals and families sometimes have to deal with the decision of choosing to extend a life that will experience pain and suffering for an indeterminate time, or ending it before it becomes physically and mentally unbearable.
Human rights is based on the premise that individuals should have the right and opportunity to freely determine their “destiny”. Thus it can be implied indirectly that individuals should have the ability to determine the end of their lives. But this right has been taken away, as mentioned explicitly in most constitutions of countries around the world.
Sue Rodriguez asked an important question before her demise while seeking euthanasia. She questioned that if she cannot give consent to her own death, then whose body is it? Another factor supporting euthanasia is the right to religious freedom. Religions such as Jainism support euthanasia. Thus banning euthanasia implies an indirect suppression of the right to practice any religion which also means that the individual's free will is being opposed here.
But one of the strongest arguments against euthanasia is this: When an individual is in such an amount of pain that he/she demands euthanasia by his/her free will, the individual cannot fathom the future implications of the decision and is merely asking for something that he/she hopes will end the pain. Thus the "will" that is being talked about here is not 'free will' but rather is 'desperate response to pain'.
Most of the individuals asking for euthanasia are patients suffering from terminal diseases. It is possible, to some extent, that the diagnosis might be wrong and the disease is curable. Here it becomes the duty of other humans to bypass the patient's free will and ensure his/her survival until the correct diagnosis is made and the treatment is given.
Rights and responsibilities are two sides of the same coin. Individuals have rights as members of the family. That means they also have responsibilities. Each person is an integral part of the family and their likes and dislikes are intricately woven into those of other family members. Mere presence can give strength to them. So the next question is, does a person really have a "free will"? Can he/she be selfish and suo moto decide to end his/her life? Can the void left by the individual's departure ever be filled? The family members and close friends may be left guilt-ridden for the rest of their lives for not having done enough to alleviate the individual's suffering.
Yes, quality of life is affected, no doubt. But adjustments can be made. There are miraculous recoveries also (links are shared below the answer.) So just hanging in there may change the picture completely.
Thus individual free will should attract moral culpability on the issue of euthanasia. But the legalization of euthanasia is a far bigger step than attracting mere attention.