Conservation and natural resource management are increasingly attending the ethical elements of public decisions. Ethical considerations are challenging, in part, because they typically require accounting for the moral consideration of various human and nonhuman forms of life, whose interests sometimes conflict (or seem to conflict). A valuable tool for such evaluations is the formal analysis of ethical arguments. An ethical argument is a collection of premises, logically interrelated, to yield a conclusion that can be expressed in the form, "We ought to…" According to the rules of logic, a conclusion is supported by an argument if all its premises are true or appropriate and when it contains no mistaken inferences. We showed how the formal analysis of ethical arguments can be used to engage stakeholders and decision-makers in decision-making processes. We summarised the method with ten specific guidelines that would be applicable to any case. We illustrated the technique using a case study focused on captive-bred lions, the skeletons of which form part of an international trade to supply traditional medicine markets in Southeast Asia with felid bones. As a matter of public policy, the practice is a complicated nexus of concerns for entrepreneurial freedom, wildlife conservation, and the fair treatment of animals.