This volume elucidates the pivotal ethical and legal issues arising from the use of brain organoids for research, therapeutic and enhancement purposes. The function of the human brain is still a mystery. Until recently, only post-mortem tissue was available for a structural examination of the brain. Consequently, the examination results could only reflect the state at the end of life. However, in order to better understand the development and function of the human brain, dynamic and functional investigations of different human brain cells are necessary. This is where brain organoids, artificially grown in vitro miniature brains, provide the opportunity for more flexible research scenarios. At the same time, however, the use of brain organoids in research and therapy raises the question of how these new entities are to be treated from an ethical and legal point of view. Against this background, this volume aims at clarifying the normative implications of the use of brain organoids in research and therapy.  The ethical reflections on the status of brain organoids, informed consent, human-to-animal chimeras and neuro-enhancement are mirrored by corresponding legal analyses. The ethical and legal assessments are preceded by an introduction to the scientific and medical background of the brain organoid technology. A final chapter will be devoted to the issue of whether international harmonization of normative standards for brain organoid research and therapy is feasible and advisable.