Pictures of same sex-couples getting married in Canberra will be seen around Australia and the world this weekend.

Gay activist Rodney Croome believes the images will have an enormous impact on Australian public opinion about marriage laws.

He says weddings next to The National Carillon, at the National Arboretum, the Old Parliament House rose gardens and at other prominent Canberra locations will increase the push for same-sex marriage to be legally recognised across Australia.

"I think historians will look back and they will see that this was the defining moment, regardless of what happens in the High Court,'' Croome says during a break from lobbying federal politicians on same-sex marriage.

"The fact that couples are married on Australian soil for the first time will be seen as the turning point.

"Images of those weddings will be broadcast across the nation.

"Ordinary Australians will see, perhaps for the first time, that this isn't ultimately about the law or about the constitution or about politics. But it really is about love, commitment and all of those values that we associate with marriage.''

ACT Attorney-General Simon Corbell agrees with Croome about the significance of this weekend's marriages.

Corbell has spent years championing civil partnership laws for gay and lesbian couples and now the ACT's marriage equality law.

"I've always said that the war on same-sex marriage has already been won; it's just that there might be a few more battles to fight,'' Corbell says.

A lone protester outside the ACT Legislative Assembly this week was in some ways emblematic of the debate about the ACT same-sex marriage law.

People wanting to publicly argue against the principle that same-sex marriage is wrong have been thin on the ground in Canberra.

At times this has led to criticism that media coverage of the issue has been one-sided.

The Labor Party has a conscience vote on same-sex marriage but all eight of its MLAs in the 17-seat Legislative Assembly supported the marriage equality bill.

Greens minister Shane Rattenbury also voted for the bill.

That left the eight Liberal MLAs as the only opponents in the parliament.

The Liberals enforced rigid party discipline and leader Jeremy Hanson acted as the only spokesman on it.

Hanson's official line is that marriage is a federal matter and none of the party's MLAs have been willing to criticise the law on other grounds.

In mounting the High Court challenge to the ACT law, the federal government has simply argued that a territory-based marriage law is incompatible with federal statutes.

The representatives of several Christian denominations and Islamic and Jewish leaders waited until the day before the same-sex marriage bill was debated in the Legislative Assembly last month to publicly issue a joint letter of opposition.

Although many Christians oppose same-sex marriage, few have involved themselves in public campaigning or protests.

The new Catholic Archbishop of Canberra and Goulburn, Christopher Prowse, was asked about same-sex marriage during a press conference after his recent installation.

Prowse reiterated the church's opposition to same sex-marriage and said the debate could be detracting attention from the support traditional heterosexual marriages and families needed.

"'The real issue that we should be looking at is the fragile state of heterosexual traditional families,'' he said.

"The same-sex issue tends to be moving the compassionate glare of Australians to another issue - although allied, I don't think it's the real issue.''

Australian Christian Lobby managing director Lyle Shelton is not afraid to speak out against same-sex marriage.

Shelton hopes the High Court will quash the ACT law. He argues that if the court ruling goes his way, the Australian public deserves a break from the same-sex marriage debate.

''[There is] a lot of parliamentary time that has been given to this,'' Shelton says.

"There's been state parliamentary inquiries but the ACT declined to have one. There's been a House of Representatives inquiry, there's been a Senate inquiry.

"These inquiries all found there's no discrimination against same-sex couples. We've had an election campaign in part on same-sex marriage. Kevin Rudd promised to legislate within 100 days.

''Voters were underwhelmed with that and Labor recorded its lowest vote in 100 years. The Greens - the party of same-sex marriage - lost 600,000 votes.''

If the political debate continues, Shelton says, it should be settled by a referendum.

"We live in a democracy, it's a free society,'' Shelton says.

"If those proponents of same-sex marriage want to continue with their campaign that's fine, but I think having exhausted all of those options, it would be time to go to a referendum of the people. That would be the way to solve it, I think.''

A referendum this week saw the majority of Croatians reject the possibility of same-sex marriage. Voters in the Republic of Ireland will have their say on the issue through a referendum in 2015.

As yet, there have been few voices calling for a referendum in Australia.

If the High Court rules in favour of the ACT law, Shelton will be pushing for the Federal Parliament to do "something'' to ensure Australia has a uniform marriage law.

Shelton dismisses the argument put by some opponents that the Christian Lobby does not represent the opinion of a majority of Christians and is not a peak body for the major denominations.

"We're not a peak body for them but I think we certainly reflect a large body of thinking and concern among the Christian constituency within the nation,'' he says.

Rodney Croome believes that if the High Court leaves the ACT law in place, other states will soon follow suit and legislate for marriage equality.

"The Tasmanian Parliament is only two votes short of supporting the law. In the NSW Parliament, there's quite a lot of support, as there is in the South Australian Parliament. There's a Coalition conscience vote in the West Australian Parliament.''

Croome was due to attend some of the first same-sex weddings at the weekend.

But he arrived in Canberra several days early to attend the High Court hearing on same-sex marriage and to meet with federal MPs and senators.

Although Prime Minister Tony Abbott still refuses to allow a conscience vote for Coalition MPs, Croome believes there is significant support for same-sex marriage within the ranks of the Liberal and National parties.

''The lobbying that we've undertaken this week reveals to me there is significant support in the Coalition party room for a conscience vote and that there are Coalition members who are yet to declare their support for this but would if there was a conscience vote,'' he says.

"Whether or not that means there's a majority in favour, it's impossible to say.''

Croome was heavily involved in the fight to have anti-gay laws repealed in Tasmania during the 1990s.

He says he is amazed how community attitudes towards homosexuality have changed in Australia in the 15 years since Federal Parliament stepped in to overturn the laws which had seen gay Tasmanian men jailed.

"Things do seem to have changed very quickly,'' Croome says.

"And where I see that change most clearly is when I talk to people of this generation.

"I am constantly amazed by how accepting young heterosexual Australians are of the idea of marriage equality and of their gay and lesbian friends and family.

"It really just isn't an issue for people under 30 … it gives me great hope for the future.''

Croome says marriage equality will help end the stereotype of gay people only being interested in short-term, sexually-driven relationships.

"To say that same-sex couples cannot marry is to say that we cannot commit. It reinforces all of the stereotypes that continue to persist against same-sex couples,'' he says.

Although marriage equality advocates have pushed for state and territory same-sex marriage schemes, their ultimate goal is to see the federal Marriage Act changed.

Marriages made under the ACT law will not be recognised by the federal government or in other states and territories.

Couples who wish to divorce will have to do so in the ACT Supreme Court, instead of the Family Court.

Issues related to child custody would then have to be resolved in the Family Court, which would recognise the divorced couples as separating de factos.

Same-sex marriages made under the ACT law won't really have equal status with heterosexual marriages recognised by the Marriage Act, but that is the best the territory Assembly could do.

The Assembly was limited by its place in Australia's federal system.

The High Court must now decide if the ACT law is in conflict with the federal Marriage and Family Law acts and the ACT Self-Government Act.

Trying to ensure the ACT bill had the best chance possible of surviving a High Court challenge sparked division among marriage equality advocates.

The Australian Marriage Equality group argued that the ACT bill should have been more carefully worded, using the term "same-sex'' marriage throughout to avoid being declared incompatible with the federal Marriage Act.

It is possible the High Court could overturn the law but leave the door open to differently worded territory same-sex marriage legislation.

If this occurs, the ACT government will bring the issue back to the Legislative Assembly next year.

Croome believes the ACT should have taken the more cautious option, using language to more carefully differentiate local same-sex marriages from marriages made under federal law.

Tasmanian and NSW bills - so far rejected by the relevant state parliaments - took that approach.

"If couples can be legally married, it's not second-best,'' Croome says.

"I'm a strong champion of the Tasmanian model and as we've publicly said before, we think the ACT should have gone with that to start with.''

But although he is not entirely sure they used the right words, Croome gives the ACT government credit for pioneering same-sex marriage while other state administrations have failed.

ACT Deputy Chief Minister Andrew Barr was instrumental in getting federal Labor's platform changed to embrace same-sex marriage.

Barr and his partner Anthony Toms legally formalised their relationship through a civil-union ceremony in 2009.

Barr says the ACT's various pieces of civil union legislation have helped transform the lives of people who were previously second-class citizens.

He believes hosting Australia's same-sex marriages is a fitting way to mark Canberra's centenary year.

"The family is the basic unit in our society, but family can take many forms,'' Barr says. ''Labor's equality reforms are pro-family. They strengthen family. They strengthen relationships.

"It will also help ensure that same-sex couples receive the dignity and respect to which they are entitled.''

As Treasurer and Tourism Minister, Barr has also been open about the economic benefits same-sex marriage could have for the ACT.

Although the territory government hopes other states will simultaneously enact same-sex marriage laws, it is looking forward to the boost wedding tourism will bring to the capital.

But the government also believes that identifying as pro-LGTI (lesbian, gay, bisexual, trans/transgender and intersex) is good for Canberra's "brand'' and will help attract new residents and investment. A rainbow version of Canberra's new "CBR'' logo is doing the rounds and some buildings were expected to be lit with rainbow lights at the weekend.

The High Court may at least temporarily extinguish Canberra's reputation as the ''rainbow capital'' next week but that won't end the local or national debate on same-sex marriage.

Peter Jean is Chief Assembly Reporter

Twitter: @pjean01