From what I understand the decision also has to be agreed with parents, doctor and psychiatrist so it isn't really totally in the childs hands. Personally i can't even begin to think what it must be like for a family that finds themselves in that position. Having said that I don't agree with it, a child is not allowed to do certain things because they are not mature enough to make appropriate decisions and this would be by far the most difficult decision anyone would have to make.