Much of bioethical discourse now takes place across cultures. This does not mean that cross-cultural understanding has increased. Many cross-cultural bioethical discussions are marked by entrenched disagreement about whether and why local practices are justified. In this paper, I argue that a major reason for these entrenched disagreements is that problematic metaethical commitments are hidden in these cross-cultural discourses. Using the issue of informed consent in East Asia as an example of one such discourse, I analyze two representative positions in the discussion and identify their metaethical commitments. I suggest that the metaethical assumptions of these positions result from their shared method of ethical justification: moral principlism. I then show why moral principlism is problematic in cross-cultural analyses and propose a more useful method for pursuing ethical justification across cultures.