Simple Summary Are we morally justified in using animals in biomedical research and if so, how can we make sure that the experiments are conducted in a scientifically and morally acceptable manner? Based on our own experiences as scholars from various academic backgrounds, we argue that this question can only be answered as an interdisciplinary and international endeavor. Thus, our article aims to contribute to the foundation of the emerging field of animal research ethics, combining perspectives from research ethics, animal (...) ethics, science, and law. In doing so, we describe the following seven phases that animal experiments typically run through: ethical, legal and social presumptions (phase 0), planning (phase I), review (phase II), conduct of experiments (phase III), publication/dissemination (phase IV), further exploitation of results (phase V), and evaluation (phase VI). Here, 20 key ethical, legal, and practical challenges are identified and analyzed that need to be addressed. Apart from challenges arising at the level of the experiments themselves, there are also so-called meta-challenges associated with animal research ethics as a field. Four of these are presented and further discussed, also in relation to their opportunities for the further development of animal research ethics that takes into account interdisciplinary and international perspectives. Abstract Can nonhuman animals be used for the benefit of humans in a scientifically and morally justified manner and, if yes, how? Based on our own experiences as scholars from various academic backgrounds, we argue that this question can only be answered as an interdisciplinary and international endeavor, considering insights from research ethics and animal ethics as well as scientific and legal aspects. The aim of this article is to contribute to the foundation of the emerging field of animal research ethics. In doing so, we describe the following seven phases of animal research experiments: ethical, legal and social presumptions (phase 0), planning (phase I), review (phase II), conduct of experiments (phase III), publication/dissemination (phase IV), further exploitation of results (phase V), and evaluation (phase VI). In total, 20 key ethical, legal, and practical challenges that an ethical framework for the use of animals in research needs to address are identified and analyzed. Finally, we characterize the following four meta-challenges and opportunities associated with animal research ethics as a field: (1) moral pluralism, (2) the integration of views and positions outside the laboratory, (3) international plurality of conduct, standards, and legal norms, and (4) interdisciplinary education. (shrink)