The Constitutional Court sided with two women who complained they were refused permission to marry by authorities in the capital Vienna.
"Today, the differentiation between marriage and legally registered partnerships can no longer be upheld without discriminating against same-sex couples", the court said.
Since 2010, same-sex couples have been allowed to enter into a civil partnership. It will keep civil partnerships as an option and will open them up to straight couples. He said the Austrian court was the first in Europe to reject a marriage ban for same-sex couples, while other countries legalized gay marriage through political means.
However, in the state's laws on marriage it had been explicitly stated that only two people of the opposite sex could marry.
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According to Shen, the drills involved fighter jets, reconnaissance aircrafts, and surface-to-air missile units. The Marine Corps earlier this year stationed a squadron of F-35Bs at Marine Corps Air Station Iwakuni in Japan.
ILGA-Europe are sending all our congratulations to the LGBTI activists, legal experts (including Helmut Graupner who represented the couple involved in this case throughout their journey), supporters of the Ehe-gleich citizen's initiative, and all the allies who stood together to call for equality.
It added that keeping the two institutions separate suggests that "people with same-sex sexual orientation are not equal to people with heterosexual orientation".
The far-right Freedom Party (FPO), Kurz's chosen government coalition partner criticised the ruling. A marriage between women and men needs protection as only these partnerships can create children, he said. In Germany, homosexual marriage was approved in June by a vote in Parliament.
LGBT rights advocates in Austria have celebrated a landmark ruling that paves the way for same-sex marriage in the country.