The UK's Girl Guiding organization will now only allow women and girls to join.The organization announced Tuesday that it will no longer accept trans girls into any of its groups.The statement says it "has reached the difficult decision that going forward membership of Girlguiding will be restricted to girls and young women."They say that girls and young women are "defined in the Equality Act (2010).".In the UK's Equality Act (2010), the definition of "sex" was interpreted in a recent Supreme Court ruling.The act itself determines the rules for single sex organizations and spaces having the right to exclude members of the opposite sex.Reported by the BBC in April, the Supreme Court's interpretation of "woman" was based on biological sex under the Equality Act (2010). Starting Tuesday, boys who identify as girls will no longer be able to join girl guide groups; however, those already a part of the organization will not experience any "immediate changes.".Girl Guiding also stated that no adult members will be affected by the changes, stating, "we are confident that no volunteers will have to leave the organization."The overall changes were made due to legal advice and consultation from its members.Although official guidelines have not been published, draft guidelines by the Equality and Human Rights Commission (EHRC) on how to interpret the law were given to the UK government in September and were recently leaked. The BBC reports Girl Guiding was facing legal action from a parent who felt the organization was failing to follow the law.