A heterosexual couple with "deep-rooted" ideological objections to the institution of marriage have vowed to continue their legal battle for the right to enter into a civil partnership.
Following a High Court defeat, Rebecca Steinfeld and Charles Keidan said the fight on behalf of themselves and more than 36,000 people who have signed their petition "calling for civil partnership equality" had not come to an end.
Academics Dr Steinfeld, 34, and Mr Keidan, 39, of Hammersmith, west London, have been in a committed relationship since November 2010 and have an eight-month-old baby.
They want to secure legal recognition of their relationship through a civil partnership, but are prevented because the Civil Partnership Act 2004 stipulates that only same-sex couples are eligible.
They argue that the Government's position on civil partnerships is "incompatible with equality law", but on Friday a judge in London dismissed their judicial review action.
Although Mrs Justice Andrews concluded that their claim "must fail", she gave the go-ahead for the couple to take their challenge to the Court of Appeal because it raised issues of "wider importance".
After the ruling, Dr Steinfeld said: "We made this claim because the UK Government is barring us, and many thousands of opposite-sex couples like us, from the choice of forming a civil partnership, and we want this to change."
She said: "We don't think there is sufficient justification for stopping us or other opposite-sex couples from forming civil partnerships. Unfortunately, the judge has concluded otherwise."
Mr Keidan said it was "now time for Parliament to demonstrate its commitment to creating a level playing field for all its citizens by opening up civil partnerships to same-sex and opposite-sex couples alike".
Explaining her ruling, the judge said she did "not accept" that the enactment of the Marriage (Same Sex Couples) Act 2013 had caused restrictions under the Civil Partnership Act on opposite-sex couples entering into a civil partnership "to become unlawful".
Those provisions had "not become incompatible" with Articles 14 and 8 of the European Convention on Human Rights - articles which prohibit discrimination and protect the right to respect for family and private life - "just because same-sex couples now have two routes to achieving legal recognition of their relationship by the state and opposite-sex couples continue to have only one".
Mrs Justice Andrews said: "By deciding to wait until it is in a better position to evaluate the impact of the 2013 Act on civil partnerships before taking any legislative steps, against a background where there is no consensus either domestically or within Europe as to the appropriate course to take, the Government is acting well within the ambit of discretion afforded to it with regard to the regulation of social matters.
"Opposite-sex couples are not disadvantaged by the hiatus, because they can achieve exactly the same recognition of their relationship and the same rights, benefits and protections by getting married, as they always could."
She concluded: "The Government's decision to wait and see serves the legitimate aim of avoiding the unnecessary disruption and the waste of time and money that plunging into a programme of legislative reform without waiting is likely to produce. Consequently, this claim for judicial review fails."
A Government spokeswoman said: "We welcome the court's ruling that the current regime of marriage and civil partnership does not disadvantage opposite-sex couples."