Christie Elan-Cane previously argued the UK’s passport application process is inherently discriminatory, but judicial review action was dismissed in June.
Clifford Chance, the firm which represented Ms Elen-Cane, has now been granted permission by the English Court of Appeal to challenge the High Court’s finding.
It had previously said the decision to not have ‘x’ genderless passports was legal.
Narind Singh, who is leading the Clifford Chance team, said: “This case raises important questions regarding the right to respect for individuals’ identity, and we look forward to working with campaigner Christie Elan-Cane as we appeal the High Court’s decision.
“Gender identity is a fundamental part of an individual’s intimate, personal identity and X-passports are a crucial step in the protection of the human rights of this group of individuals.”
In the earlier case, the High Court found for the first time in the UK that non-gendered identity was entitled to recognition and protection under international human rights law.
This was despite it still upholding that gender neutral passports did not have to be offered.
At the time, Elen-Cane said the impact of the refusal to provide for X passports “affects not only non-gendered persons such as the claimant, but a broad section of the public”.
They stated this included intersex and transgendered people and other individuals with gender dysphoria.
At the time, James Eadie QC on behalf of the Home Secretary submitted that the policy does not interfere with rights under the ECHR.
Leonne Zeegers, 57, was handed a travel document with the gender designation X as opposed to the country’s usual M for man or V for woman.
Countries including Argentina, Australia and Canada are among other countries with gender neutral passport applications available.