In Evangelium Vitae, Pope John Paul II speaks of the responsibility with which health-care personnel should carry out their duties, in particular their responsibility in upholding life in all circumstances.
A unique responsibility belongs to health-care personnel; doctors, pharmacists, nurses, chaplains, men and women Religious, administrators and volunteers. Their profession calls them to be guardians and servants of human life. In today's cultural and social context, in which science and the practice of medicine risk losing sight of their inherent ethical dimension, healthcare professionals can be strongly tempted at times to become manipulators of life or even agents of death. In the face of this temptation their responsibility today is greatly increased. Its deepest inspiration and strongest support lie in the intrinsic and undeniable ethical dimension of the health-care profession, something already recognized by the accident and still relevant Hippocratic Oath, which requires every doctor to commit himself to absolute respect for human life and its sacredness. (89.2)
Absolute respect for every innocent human life also requires the exercise of conscientious objection in relation to procured abortion and euthanasia. “Causing Death” can never be considered a from of medical treatment, even when the intention is solely to comply with the patient's request. Rather, it runs completely counter tot he health-care profession, which is meant to be an impassioned and unflinching affirmation of life. Biomedical research too, a field which promises great benefits for humanity, must always reject experimentation, research or applications which disregard the inviolable dignity of the human being, and thus cease to be at the service of people and become instead means which, under the guise of helping people, actually harm them. (89.3)