The current legal status and medical ethics of routine or religious penile circumcision of minors is a matter of ongoing controversy in many countries. We focus on the United Kingdom as an illustrative example, giving a detailed analysis of the most recent British Medical Association guidance from 2019. We argue that the guidance paints a confused and conflicting portrait of the law and ethics of the procedure in the UK context, reflecting deeper, unresolved moral and legal tensions surrounding child genital (...) cutting practices more generally. Of particular note is a lack of clarity around how to apply the “best interests” standard—ordinarily associated with time-sensitive proxy decision making regarding therapeutic options for a medically unwell patient—to a parental request for a medically unnecessary surgery to be carried out on the genitalia of a healthy child. Challenges arise in measuring and assigning weights to intended sociocultural or religious/spiritual benefits, and even to health-related prophylactic benefits, and in balancing these against potential physical, functional, and psychosexual risks or harms. Also of concern are apparently inconsistent safeguarding standards being applied to children based on their birth sex categorization or gender of rearing. We identify and discuss recent trends in British and international medical ethics and law, finding gradual movement toward a more unified standard for evaluating the permissibility of surgically modifying healthy children's genitals before they can meaningfully participate in the decision. (shrink)