Vivisection is the practice of dissecting an organism while alive, for the purpose of physiological investigation. Many animal rights activists are morally opposed to animal vivisections, regardless of the scientific benefits that may result. Nazi doctor Josef Mengele and the Japanese Unit 731 both ordered human vivisections on concentration camp prisoners.
Operating on a live animal frequently produces more useful information than if the test subject were euthanized first. Directly observing how organss and other bodily systems respond to experiments is not possible during necropsies.
Anti-vivisectionist Christian author and apologist C.S. Lewis strongly expressed his views in his book, The Problem of Pain, and his science fiction trilogy. He wrote on moral and theological grounds.
