British Prime Minister Theresa May said on Tuesday that England and Wales would amend their marriage laws to allow opposite-sex couples to enter into civil partnerships.

The decision was announced Tuesday at a conference of May's Conservative Party. It followed a U.K. Supreme Court ruling that not making heterosexual couples eligible for civil partnerships violated the European Convention on Human Rights.

"There are all sorts of reasons why people may choose not to marry," May said in a statement released by her party.

"By giving couples this option we hope to give them and their families more certainty and security."

The ruling came in a case involving a couple that wanted to avoid the "patriarchal baggage" of marriage. Rebecca Steinfeld and Charles Keidan argued that limiting the partnerships to same-sex couples was discriminatory.

The five Supreme Court judges said the government had declined to amend or abolish the Civil Partnership Act 2004 when it introduced a law in 2013 to allow the marriage of same-sex couples.

They noted that Steinfeld, 37, and Keidan, 41, had "genuine ideological objections to marriage based upon what they consider to be its historically patriarchal nature."

The couple's lawyer, Louise Whitfield, said the court had been clear that "the government's failure to act was unlawful and discriminated against my clients."

"Wonderful news," Keidan tweeted, thanking equalities minister Penny Mordaunt "for her commitment" to extending civil partnerships.

"We literally can't wait," Steinfeld tweeted. "Please set your date to legislate, so we can set our dates to celebrate!"

Same-sex couples have been able to form civil partnerships in Britain since 2005, giving them the legal protections, adoption and inheritance rights as married heterosexual couples.

The country legalized same-sex marriage in 2014.

The Supreme Court ruling did not cover Scotland, whose government last week entered into consultations about whether to make the same change.

The British government says there are more than 3.3 million unmarried couples in the United Kingdom who live together and share their financial responsibilities.

Nearly half of them also have children.