The overall goal of this subproject is to reconsider the legal criterion of "totipotency" (and the underlying "potentiality argument"). The legal term "totipotncy" will be clarified by defining decisive criteria both on the legal and on the constitutional level, be applied to entities resulting from reprogramming of somatic cells (into iPS cells) and from the application of cdx2-mRNA-interference, and be contrasted with the biological concept of "totipotency". In addition, the subproject will study the methodological problem in what way ethical considerations might be incorporated into constitutional reasoning. Finally, the subproject will address the legal consequences for the legislative arising from empirical uncertainty with regard to the existence of totipotency.