The Gender Recognition Act 2004 provides for individuals in the UK to change gender from male to female or female to male. It also provides for the UK to recognise a gender acquired under the law of a foreign state or territory. A number of foreign states and territories recognise genders other than male and female.
Ryan Castellucci acquired nonbinary gender under the law of the State of California. Ryan applied for recognition of their acquired gender in the UK. They argued that there is nothing unusual about the UK recognising foreign statuses that cannot be obtained in the UK (such as polygamous marriages) out of respect for international comity.
On 25 February 2025, the Court of Appeal ruled that the Gender Recognition Act 2004 does not allow for the recognition of foreign acquired genders other than male or female because, notwithstanding the wording of the foreign-recognition provision, the Gender Recognition Act is based on binary notions of gender. Ryan has indicated that they intend to apply for permission to appeal to the Supreme Court.
Chris Buttler KC represented Ryan Castellucci, leading Marlena Valles, instructed by Anna Dews and Kate Egerton at Leigh Day.