Same-sex couples will be allowed to marry in Austria from 2019, the country's supreme court ruled on Tuesday and said a law to the contrary violated the principle of non-discrimination.
The court has determined that December 31st 2018 is the deadline for the government to change the legislation, although the government could choose to enact the change sooner.
"Today, the differentiation between marriage and legally registered partnerships can no longer be upheld without discriminating against same-sex couples", the court said.
It added that keeping the two institutions separate suggests that "people with same-sex sexual orientation are not equal to people with heterosexual orientation".
Previously marriage was defined as for "different sex" partners.
Both parties voted against same-sex marriage when it came before parliament earlier this year.
Same-sex couples will be allowed to get married in Austria by 2019, the country's top court has ruled.
The move brings Austria into line with other European countries including Germany, England, Scotland, Wales, Ireland, France and Spain. The country is in something of a state of political flux at the moment, with the conservative People's Party now negotiating with the hard-lined far-right Freedom Party to form a coalition Government following on from general elections in October. It acted at the request of two women who were rejected by two lower authorities.
"We are very happy", said The Homosexual Initiative Vienna (HOSI) chairman Christian Hoegl. However, in the state's laws on marriage it had been explicitly stated that only two people of the opposite sex could marry.
In 2011, the Netherlands became the first country in the world to allow gay marriage, and more than a dozen European countries have since followed suit.