The following article was first published on the Drum.

In his recent Michael Kirby Lecture, Malcolm Turnbull made an excellent case for same-sex marriage that came to an appalling conclusion, civil unions.

Part of the problem is that Turnbull has his facts wrong.

For example, his claim that civil unions are “better than nothing” has been shown by the overseas experience to be false.

Studies into the impact of existing civil union schemes in the US and Europe have all come to the same conclusion: civil unions have failed to fulfil their promise of equality and can actually make things worse.

The most recent study, from Illinois, shows that even when the law says civil union couples have equal rights, these couples routinely face discrimination in everything from housing to health care because too few people understand what a civil union means.

The same lack of understanding permeates everyday relationships, with family and work colleagues unsure how to relate or even refer to civil union partners.

This shouldn’t be a surprise. Civil unions don’t create kinship like marriage. They don’t connote family and belonging. They carry no tradition. In the words of one US wit, no-one writes love songs about civil unions.

But even worse than this, civil union schemes have been found to foster discrimination by entrenching a separate and lesser status for same-sex couples. According to the report of the New Jersey Civil Union Review Commission, that state’s civil union scheme,

“…imposes a second-class status on same-sex couples and sends the message that it is permissible to discriminate against them. Witnesses called the two-tier system created by the Civil Union Act ‘an invitation to discriminate’ and a ‘justification to employers and others’ to treat same- sex couples as ‘less than’ married couples. According to the testimony, the Civil Union Act amounts to a tacit endorsement of discriminatory treatment.”

“The impact of this discrimination and stigmatisation is felt most keenly by the families and children of same-sex civil union partners. Many witnesses noted that the labeling of civil union couples, not as married but in a civil union, has a detrimental effect on their families, showing children that their parents are different or somehow less than others, which can lead to teasing and bullying. Many witnesses observed that when the government treats people differently, it emboldens private citizens of any age to follow suit.”

Again, this shouldn’t be a surprise. One reason marriage equality is important is that it is a key step towards integrating gay, lesbian, bisexual and transgender people more fully into the families and communities of which we are a part. Anything which perpetuates a separate status is a step in the opposite direction.

Because civil unions create more problems than they fix, they have been rejected by same-sex couples.

In the US, same-sex couples are twice as likely to marry than enter a civil union.

A University of Queensland survey found sentiment is even stronger in Australia with 80% of same-sex partners saying they want marriage equality and only 25% preferring civil unions. In the same survey, partners in Australian state and territory civil partnerships overwhelmingly said they would prefer to marry.

Civil unions have also been dismissed as an inadequate and unnecessary step by many of the governments that have moved to recognise same-sex marriages.

Contrary to Mr Turnbull’s assertion, Spain explicitly rejected civil unions and went directly to marriage equality. So did New York, Massachusetts, Connecticut, Portugal and South Africa.

Before embracing marriage equality, Canada, Argentina and the Netherlands had various forms of civil unions at a local level, as we do in Australia with state civil partnership schemes that already cover 80% of the Australian population. But when it came to reform at a national level all these foreign countries opted for full equality instead of civil unions.

It’s true that some countries like the UK and France are now moving from national civil union schemes to marriage equality.

But there’s no evidence that the existence of civil unions has made that transition any easier. If anything it has retarded the kind of healthy marriage equality debate we have had now in Australia for several years (which may be why there seems to be a fiercer backlash to marriage equality in Britain than in Australia).

If Britain and France are moving towards marriage equality it is not because they have evolved to any great degree. It is because the western world has evolved beyond the mistake of civil unions (as Barack Obama’s recent endorsement of marriage equality and rejection of civil unions so clearly showed).

So why does Malcolm Turnbull want to exempt Australia from the global trend?

Why does he want us to embark on an experiment that has failed everywhere else?

The answer is self interest.

When Turnbull said in his Kirby Lecture “it is a great mistake to allow your conception of the perfect to be the enemy of the good”, I fear “the good” he referred to was not what is good for same-sex couples but what is good for him as a politician.

According to Turnbull’s own electorate survey, 72.7% of his constituents support marriage equality while only 16.8% support civil unions.

Clearly, Turnbull will have to deliver his constituents something before the next election or face their wrath.

But as a member of the Shadow Cabinet he is bound by the position of his leader, Tony Abbott, who opposes same-sex marriage and, in a radical over turning of Liberal Party tradition, refuses to allow a conscience vote on it.

If Turnbull was to cross the floor, or even abstain, during a vote on marriage equality his hope of a powerful ministry after the next election will be dashed.

Turnbull is torn between the two jobs that make him who he is – a representative of Sydney’s socially-progressive eastern suburbs and a national political leader.

His way through is to say all the right things about marriage equality but do his best to persuade supporters of this reform that what they really want is something less.

There’s an obvious parallel with the republican campaign Turnbull led in the late 1990s.

He championed a minimal republic with presidents elected by parliament because it seemed more achievable than having a directly-elected head of state.

Unfortunately for Turnbull his republican model failed – just as his civil union model fails – precisely because it was a compromise that not enough people really wanted.

But there is also a crucial difference between marriage equality and the republic.

Exclusion from a core legal and social institution affects people on a day-to-day basis in the way having a Queen does not.

This is why support for marriage equality has grown so quickly and continues to gather unstoppable momentum.

And it is why Turnbull’s biggest mistake of all is to base his support for civil unions on the judgement that “the numbers are not there for gay marriage in this parliament”.

They may not be, yet. But every week new supporters come out in both major parties.

For example, just in the last fortnight Minister for State, Gary Gray, and Liberal Senators Sue Boyce and Simon Birmingham, have endorsed marriage equality, while the reform has got the thumbs up from a Senate inquiry and former Liberal Premiers, Nick Greiner and Jeff Kennett.

Going on how quickly support is growing, the numbers will be there much sooner than any of us expect, and not even Tony Abbott will be able to stand in the way.

In this environment, to opt for a compromise that will satisfy no-one and set back the cause of the very people it is meant to help, is not the kind of wise, considered, progressive step that resonates with the legacy of Michael Kirby.

Indeed, it stands against that legacy as an act of political expediency the rest of the western world will snigger at and the nation will quickly come to regret.

If there’s one international lesson about marriage equality that Malcolm Turnbull should heed above all the others it is that strong political leadership is always the final step towards achieving marriage equality.

The real choice he faces is not between marriage equality and civil unions, but between helping lead the movement for marriage equality or simply flowing along in its wake.