Having now read the Australian Capital Territory’s Marriage Equality (Same Sex) Act 2013, I can reach no other conclusion than it is deliberately designed to fail. Far from being a genuine attempt to advance the cause of marriage equality, it seems little more than a political stunt aimed at trying to embarrass Prime Minister Tony Abbott.

I am not a QC or expert in constitutional law, but having served for six years as the Australian Democrats’ spokesman for the attorney-general’s portfolio I did come to grips with the fundamentals of federal law and the limitations on state and territory trespass.

This territory act so obviously breaches aspects of the federal constitution that it is impossible for me to believe it does so accidentally. The High Court will not dwell on this issue for long. It will not split in its decision. There will be no dissenting voices.

Without going into the details of this multi-flawed act, suffice it to say that the mere fact it makes reference to the federal definition of marriage in its framework, as well as seeking to legally recognise foreign same-sex marriages in its jurisdiction, kicks this law out of bounds on the full.

So, what on earth is the ACT’s Lilliputian legislature up to?

For almost a decade the key lobby group pressing for change, Australian Marriage Equality, has been working diligently and apolitically towards bringing the nation forward. It has reached out across the crossbenches, winning support and confidence from both doubters and conservatives.

With its credible, persuasive and highly researched legal background, AME has brought the parliaments of Tasmania and New South Wales to the brink of passing state-based gay marriage laws. This has only been possible by AME arming itself with the best advice it can get from constitutional expert Bret Walker SC, among others. Walker is a former president of the NSW Bar Association and former president of the Law Council of Australia.

Walker’s main point to equality reformers, without wanting to be too simplistic in interpreting his advice, is that the states and territories do in fact have the power to act, but only where they expressly legislate for same-sex marriage outside of the federal definition of marriage. The two laws can coexist. However, trying to blend state or territory law with Commonwealth law, as the ACT does, dooms that reform to failure.

Despite the best legal advice from Walker and the best political advice from AME from multiple meetings, ACT Chief Minister Katy Gallagher and her Attorney-General Simon Corbell have forged ahead, into certain defeat.

Presumably the ACT government’s “strategy” is to try to embarrass Abbott by bringing sharp focus to the issue of marriage equality and the need for federal action. Certainly, the timing seems designed to create lots of media images of happy lesbian and gay couple getting married, only to have Big Bad Tony ruin their weddings with a successful legal challenge. If this really is the strategy, it’s dumb, self-indulgent and destructive. When the High Court rules the ACT law invalid the focus won’t be on Abbott, it will be on the ACT’s Labor government which ignored all the warnings before charging into the federal sphere like a bull in a china shop.

The saddest part of all this is that well-meaning gay couples in Canberra seem to have been cynically used as pawns in a political game by the ACT Assembly against Abbott, and worse still is the setback this defeat will bring about in other states.

When the High Court rules that the ACT law is a dead duck, the religious Right and other anti-equality campaigners will trumpet loudly that marriage is “clearly a federal issue”, and those cautious MPs in states now considering their own legislation will retreat to inaction, handballing the issue to the Commonwealth. They will not discern the subtle difference between territory and state powers to understand that states really do have a way forward if it is done properly.

The clumsy intervention of the ACT into the equal marriage campaign, in this way, at this point in time, does the overall movement in Australia a great disservice. Those responsible should be held accountable.

*Brian Greig OAM is a former Democrats senator and veteran GLBT rights campaigner