This thesis deals with some of the legal and ethical issues that arise when an individual's genital and gonadal anatomy does not match what is perceived to be the biological (or sometimes culturally determined) norm. I focus on intersex individuals, particularly infants, who may undergo genital surgery, to 'normalise' genital anatomy. I compare this type of surgery to other forms of genital cutting on those too young to consent, male circumcision and female genital mutilation (FGM). I discuss how sex is complex and not yet fully understood; intersex challenges the idea that sex is a simple binary entity and the history of 'sex testing' in sport illustrates that there are, rarely, individuals for whom categorisation as biologically male or female is impossible. Gender is also a complex entity, but institutions such as medicine and the law still endorse a simple bipolar model of sex and gender. I argue that the assumptions on which medical practice in intersex is based are based on these simplistic gender norms. I argue that one form of intersex surgery, refashioning the clitoris, continues to be seen as a valid treatment option despite the paucity of outcome data and is not treatment for an illness but for an anatomical difference. At least some individuals who have had this procedure perceive that they have been harmed by it. Therefore I argue that the current medical and surgical approach to anatomical genital variation in intersex is ethically questionable. Furthermore it is possible to construct an argument that it is not in the best interests of the young child to undergo this procedure and that it therefore may be unlawful, even when carried out with parental consent. I also argue that, if FGM is unlawful, as it is, then other analogous procedures, such as clitoral surgery for intersex and male circumcision for non-medical reasons should similarly be unlawful. Male circumcision is held to be lawful in England at present, but the English courts have not considered genital surgery in intersex infants. If they did, then the logical conclusion ought to be to proscribe it. I argue that documents such as driving licences and passports should permit a neutral gender and that birth certification ought to permit registration without specifying sex for intersex infants. It is possible that at least some of this may come about in the future, since a recently published report from the House of Commons Women and Equalities Committee on Transgender Equality has suggested change in the current situation, one indication of the current rapid pace of change in this area of Law. I argue that education about intersex and sex and gender diversity is important for healthcare professionals and for everyone.