A judge has ruled that the ban on same-sex marriage in the US state of Oklahoma is unconstitutional.

US District Judge Terence Kern ruled that the state’s ban on same-sex couples marrying violated the US Constitution.

Arguing both the right to marry, and the right to have out-of-state same-sex marriages recognised, the lawsuit under which the ruling was made was filed by two same-sex couples.

The ruling effectively made a 2004 voter-approved constitutional amendment void, however does not take effect immediately, as Judge Kern put a stay on the ruling pending a state appeal against it.

An overwhelmingly large 76% of voters approved the amendment which said: “Marriage in this state shall consist only of the union of one man and one woman”.

This stay mirrors recent events in the state of Utah, where a District Judge made a similar ruling, but a stay was put on the ruling pending appeal from the state.

Between 20 December and 6 January, some 1,300 couples married in the state as a US District Judge ruled that a ban on same-sex marriage violated the state’s constitution.

The US Supreme Court last Monday put a stay on equal marriage in the US state of Utah, forbidding same-sex couples from being issued with marriage licences in the state during an appeal against a ruling to allow them.

The Utah Attorney General Sean Reyes advised Governor Gary Herbert that marriages between gay couples who married in that short period should not be recognised by the state for benefits purposes.

US Attorney General Eric Holder has since responded to calls to say Utah married same-sex couples would be treated as married by the federal government, despite a directive from the state Governor that they would not.

The decision in Oklahoma has been hailed, as it potentially paves the way for similar rulings in other conservative leaning states.

Chad Griffin, president of the Human Rights Campaign, said: “Equality is not just for the coasts anymore. Today’s news from Oklahoma shows that time has come for fairness and dignity to reach every American in all 50 states.”