The government is to change the law to allow opposite-sex couples to enter into civil partnerships, Theresa May has announced.
In a statement issued at the Conservative Party conference in Birmingham, the Prime Minister said: "This change in the law helps protect the interests of opposite-sex couples who want to commit, want to formalise their relationship but don't necessarily want to get married.
"As Home Secretary, I was proud to sponsor the legislation that created equal marriage.
“Now, by extending civil partnerships, we are making sure that all couples, be they same-sex or opposite-sex, are given the same choices in life."
Under the current system, same-sex couples can choose to marry or register for a civil partnership whereas opposite-sex couples can only get married.
There are currently over 3.3 million unmarried couple families in the UK living together with shared financial responsibilities and nearly half of them with children.
These households do not have the same legal protections as those who have a civil partnership or marriage, says the Conservative Party.
‘More certainty and security’
Rebecca Steinfeld and Charles Keidan outside the High Court in London last year
The current system was found in June to be in breach of European law.
The Supreme Court unanimously ruled in favour of Rebecca Steinfeld, 37, and Charles Keidan, 41, from London, who launched a legal bid to be allowed to have a civil partnership.
The court said that the Civil Partnership Act 2004 - which only applies to same-sex couples - was incompatible with the European Convention on Human Rights.
The Scottish government is also carrying out a consultation on allowing mixed-sex couples to enter into civil partnerships after the ruling.
Equalities Minster, Penny Mordaunt, said: “This is an important step forward for equality. There are all sorts of reasons why people may choose not to marry.
“By giving couples this option we hope to give them and their families more certainty and security.
“I pay tribute to all who have campaigned for this change and will introduce the change as swiftly as possible.”