While the science of animal biotechnology is advancing at a rapid pace, the ethical discussion about the boundaries the public might want to set is at the most nascent stage. There is a tendency in the public debate for opponents to favor an all-out ban on the science, while proponents want to grant it carte blanche. I argue that a more nuanced position on animal biotechnology considers individual projects to be located on a moral continuum, where some are clearly morally justified, others morally impermissible, and some lie in the ethical gray-zone. To begin to define this continuum, we use the bioethical method of casuistry to analyze one case at the end of moral permissibility, and we contrast it with a case that is located at the opposite end of the moral spectrum. I advocate this approach to assessing the moral merit of biotechnology projects because of its attention to the details of individual cases — the protocols, ends, and methods — on which an accurate moral judgment necessarily rests.