In the following piece of work I acknowledge dependance on the BBC Ethics website section on Euthanasia. A link to this site is included in the 'Useful Links' page.
THE RIGHT TO LIFE
This expression is generally used in two ways in Ethics:
The Religious Approach
Religious philosophers would normally use the expression "Right to Life" in connection with the concept of the Sanctity of Life. This is the belief that as life ultimately comes from and belongs to God, only God can begin or end it, and human life must be respected and valued regardless of its stage or quality.
Christianity teaches that humans are made 'in the image of God'. This does not mean that Christians think they look like God. It means that humans have characteristics which reflect God, and these characteristics comprise an aspect of humanity that survives physical death - the soul. The soul comprises the character, personality, ambition, creativity and other aspects which Christians believe uniquely reflect and derive from God's own character. A vital question for Christians is, "Does the human soul exist from the moment of conception or does God place the soul into the foetus at some later stage?" The process of gaining the soul is known as "Ensoulment". This concept can also be called "personhood". " When is personhood attained?" is in effect the same as asking "When does ensoulment occur?"
Evangelical Christians argue that ensoulment occurs at conception. They believe that the Bible describes several people who are said to have been known by God before conception. Those people's lives, characteristics and missions are known by God before their conception. Clearly, Jesus is the prime example of such a person. The Angel Gabriel visited his mother Mary before she conceived, saying that her Son was chosen by God to save people from their sins. In the Old Testament, Samson and Jeremiah are two others whose destiny was declared before their conception. People exist in the mind of God even before their conception and therefore their destiny and ensoulment must exist within their physical form from conception. And although the New Testament contains no specific teaching about abortion, another very early Christian document, the Didache (which very nearly made it into the NT by the way) states that people who have procured abortions are in the fires of hell.
You will probably be aware that the Roman Catholic Church also insists that ensoulment happens at conception, that full personhood exists from this time and that deliberately to destroy human life from conception is equivalent to murder. However, you may not be aware that this doctrine has only been in place since the mid 1800s. Prior to that, Thomas Aquinas' teaching that a male foetus became ensouled at 40 and a female at 90 days was standard Catholic Teaching, and early abortion, though viewed as a grave sin was not equated with murder until the 19th century.
In this context then, the 'Right to Life' therefore means "God gave this life, and we humans have no right to compromise it or shorten it artificially."
In religious ethics, the principle of "Right to Life" would usually be applied to the unborn - affirming their belief that noone has the right to terminate a pregnancy, and to those with disablements of various types, affirming that their lives have dignity and should not be ended artificially. The recent case of Terri Schiavo was a case in point.
Secular philosophers have also argued for the Right to Life based on the duty to preserve life because it has value in itself, or the
importance of regarding all human beings as ends rather than means.