A bill to legalize same-sex marriage in the Australian state of New South Wales (NSW) will be introduced in the state Upper House as soon as next Thursday and all MPs will be allowed to vote with their consciences on it.

Labor member of the NSW Legislative Council Penny Sharpe will introduce the bill 31 October, with a debate on the bill to follow soon after.

Sharpe is part of a bipartisan working group on same-sex marriage in the NSW Parliament which also includes lawmakers from the Liberal, National and Greens parties as well as the independent MP for Sydney Alex Greenwich.

The campaign for the legalization of same-sex marriage in Australia has released legal advice by senior High Court barrister, Bret Walker SC, considered one of the leading constitutional experts in Australia, which confirms the NSW Same-Sex Marriage Bill is constitutionally valid.

The news that NSW will move forward with a bill follows hot on the heels of the Australian Capital Territory (ACT) becoming the first Australian jurisdiction allowing same-sex couples to wed and the state of Tasmania preparing to debate whether to bring back a bill legalizing same-sex marriage at a state level.

Australian Marriage Equality NSW co-convener, Dr Shirleene Robinson welcomed the developments.

‘After seeing the joy and happiness that accompanied the passage of reform in the ACT yesterday, it’s great that NSW is also moving ahead,’ Robinson said.

‘The advice we have from Mr Bret Walker SC is that our Bill is constitutionally sound, assuaging any concerns NSW MPs may have about their power to pass such it. NSW same-sex couples shouldn’t have to travel interstate to marry but should be able to marry at home with their families and friends.

‘I look forward to NSW becoming the first state to allow same-sex couples to marry.’

Australian Marriage Equality is encouraging supporters to call Upper House members to express their support for the bill.

Earlier this year NSW Premier Barry O’Farrell said he would allow his MPs a conscience vote and allowed an inquiry to clarify whether NSW could introduce its own legislation for same-sex marriage.

The news comes as the Australian Government has sought to expedite its legal challenge to the ACT’s same-sex marriage law in the High Court, claiming that it wants to minimize stress for couples who might be married under the law and then find their marriages invalid.

Australian Marriage Equality national director Rodney Croome said Australian Attorney General George Brandis was being ‘disingenuous’ in his claim of being concerned for same-sex couples.

‘If the Federal Government is sincere about avoiding distress for same-sex couples and ensuring consistency across Australia, it will allow a conscience vote so this reform can be passed at a federal level,’ Croome said.

‘Few things are more distressing to same-sex couples and our families than laws which exclude us from an institution which connotes love, commitment and family.’

Croome noted all relationship law reform in Australia has occurred first at a state and territory level before occurring nationally, with the sates creating de facto marriages for unmarried cohabiting heterosexual couples to protect their property rights.

‘The states and territories led the way on the recognition of heterosexual marriages, heterosexual de facto relationships, same-sex de facto relationships and civil partnerships,’ Croome said, ‘I don’t see why same-sex marriages would be any different.’

‘The Federal Government’s “national consistency” argument is really just another way of saying “nothing should change”.’