The Turnbull government is determined to push it through before Christmas, if only finally to divest itself of a "barnacle" that has beleaguered the Coalition for years now. Prime Minister Malcolm Turnbull wants the law passed this year, which means a December 7 deadline. Credit:AAP Just two parliamentary sitting weeks remain for the year, from Monday November 27 to Thursday December 7. In that time, MPs will have to agree on how to legalise same-sex marriage. A handful of MPs have vowed to ignore the public's will and vote against the bill anyway, but they are few and far between. Most know that having given the public a say, that verdict must now be reflected in law. The fundamental change is simple enough: removing the declaration, inserted in 2004 under John Howard, that marriage in Australia is the union of "a man and a woman" (although, as just one indicator of how bitter this fight could be, some conservatives want to retain that definition and add a separate clause stating marriage can also be the union of "two people").

The bigger battle will surround the "exemptions" put in place to allow religious organisations to continue to administer marriage in a way they see fit - to the exclusion of same-sex couples. Most people are in agreement that ministers of religion should not be forced to marry two people if they don't want to - and, indeed, churches already enjoy wide-ranging exemptions to anti-discrimination laws. But there is fierce disagreement over how far to extend those exemptions. Broadly speaking, social conservatives want to allow anyone who disagrees with same-sex marriage to refuse to participate in one, by legally refusing wedding services to gay couples. Others in the government, including the chief law officer George Brandis, think that would be unconscionable. "We are certainly not going to remove one form of discrimination and at the same time instate another form of discrimination," he said on Tuesday. There is also a strongly held view among moderate Liberals that, having lost the vote, opponents of same-sex marriage have no right to dictate what the law should look like.

The margin of the vote gives some ammunition to conservatives to argue on behalf of the nearly 40 per cent of Australians who voted "no", as figures such as Tony Abbott and Eric Abetz clamoured to do immediately on Wednesday. But the fact the "yes" vote exceeded 60 per cent - surpassing the expectations of many "yes" supporters in the government - weakens the ability of conservatives to agitate for exemptions. Liberal senator Dean Smith, a gay man who fought publicly and within the Coalition for same-sex marriage, released a bill earlier this year that would legalise same-sex marriage and provides protections for religious freedom. It is that bill that has been chosen by government ministers as their preferred starting point. They have flagged the possibility of amendments, potentially cherry-picked from Liberal senator James Paterson's rival bill, which would give wide-ranging exemptions and wind back existing anti-discrimination laws. However, because of the way this has been undertaken by the government, it is likely those amendments will not succeed. The government says it will allow Senator Smith's bill to be debated - starting in the Senate - and it's the Parliament's job to work out what the final version looks like.

As a conscience vote, there's no need for a consolidated party room position on any element of the bill. Given the combination of moderate Liberals, Labor and the Greens in the Senate, it's unlikely any conservative amendments would succeed. Loading Lawyers, churches, think tanks and interest groups will clamour for attention in coming weeks as they try to tell politicians what to do. But it's the voting public that MPs must now respect above all, and the people's verdict is clear: get this done, and get it done quickly.