We will keep fighting for civil partnerships for mixed-sex couples | Rebecca Steinfeld and Charles Keidan

“My overall conclusion: the appellants are right.” These were the words of Lady Justice Arden in the Court of Appeal today – and yet we lost our legal challenge to the government’s ongoing ban on mixed-sex civil partnerships.

Lady Justice Arden’s two fellow judges disagreed – and outvoted her. All of the judges were critical of the status quo, whereby civil partnerships are still only available to same-sex couples, despite 13 years passing since their introduction and clear demand for them among mixed-sex couples. But the other two judges concluded that the government should be allowed more time to make a decision on whether to extend civil partnerships to mixed-sex couples before its position becomes unlawful.

Naturally we are deeply disappointed by this ruling. The narrowness of the defeat makes it all the harder to swallow: we came so close to winning, yet lost on a technicality. Nevertheless, there is so much in the ruling that is positive.

All three judges agreed that we are being treated differently because of our sexual orientation, and that this has an impact on our private and family life. All three rejected the argument that we could just get married. And, most importantly, all three emphasised that the government cannot just wait and see indefinitely, but must make a decision quickly. As Lord Justice Beatson put it: “I do not consider that the discrimination in the status quo can be maintained for long.”

So while today’s ruling isn’t everything we’d hoped for, we have lots of reasons to keep going. We are spurred on by the incredible support from tens of thousands of people across the country who, like us, desperately want to see civil partnerships made available to all couples. More than 70,000 people have already signed our Change.org petition calling on the minister for women and equalities, Justine Greening, to do the right thing and open civil partnerships to all. We’ve received powerful, personal messages from people telling us about the heartache and material detriment they face as a result of not being allowed to form a civil partnership. The consensus on the need to address this unfairness keeps us going.

So, too, does awareness of the vulnerability of the three million mixed-sex cohabiting couples, like ourselves, in the UK. This fastest-growing family type, which includes two million dependent children, lacks the legal and financial security available to married and civilly partnered couples. That’s not fair. None of us should be denied recognition or protection because marriage isn’t right for us. So we must – and will – press on, for their sakes, as well as ours.

Lord Justice Briggs acknowledged this injustice in the ruling. “‘I can well understand the frustration which must be felt by the appellants and those couples who share their view about marriage, about what they regard as the government’s slow progress on this issue,” he said. “Some couples in their position may suffer serious fiscal disadvantage if, for example, one of them dies before they can form a civil partnership.”

We will continue the legal fight. Unless the government commits to lifting the ban on mixed-sex civil partnerships, we will be appealing this decision to the Supreme Court. Of course, doing so will not be easy, given the very high financial and emotional costs of further litigation, especially combined with our parental and professional responsibilities. But the legal challenge is only one part of a much wider campaign for change.

Together with everyone involved in the Campaign for Equal Civil Partnerships, we will build on the positive parliamentary support we’ve already received. Politicians from nearly every major party now back our cause. Conservative MP Tim Loughton’s private members’ bill to give mixed-sex couples the right to a civil partnership has received cross-party backing. The London Assembly unanimously passed a motion supporting mixed-sex civil partnerships, and the mayor of London, Sadiq Khan, is in favour of opening civil partnerships to all. The forces in favour of reform now significantly outnumber those who remain opposed. The tide turned some time ago and there is only so long that the government can continue to swim against it.

We won’t rest until the government recognises that opening civil partnerships to mixed-sex couples is fair and popular, and good for families and children. We are confident that they will, eventually, recognise this clear logic. We call on the government to announce a simple amendment to the Civil Partnership Act 2004 in the forthcoming Queen’s speech. All they need to do is remove six little words stating that couples eligible for civil partnerships “must be of the same sex”. That’s it.

Defeat today is hard to accept. But it has also given us a chance to regroup, rally, and emerge stronger. Change may take a little while longer, but it will happen and we know our efforts will be worth it in the end.