FOI Syria

That seems to be a pretty thin argument in reality, and doesn't gain any credence from the characterisation 'defensible legal argument'.

Yet in a document titled 'ADF Operations in the Middle East' (Departmental information valid as at 21 September 2015) under the subheading 'Coalition strategy in Syria' it states (emphasis added) that the:

Government took the decision to participate in air operations against Daesch in Syria based on the assessment that Daesh will continue to attach and threaten Iraq from there. The situation in Syria is complex. There are multiple conflicts involving different players-including the Assad regime and numerous rebel groups-with different objectives and different regional and international backers. The prospects for a political or military solution are poor.

Which begs the question, what on earth was the Australian Government really thinking or trying to achieve?

Documents released by the Department of Defence confirm that we have ADF embedded personnel at US CENTCOM in Tampa, Florida, to participate in the execution of any US operations against ISIL in Syria. The author of one noted in 2014 that:

The possibility of ADF embedded personnel at US CENTCOM contributing to the execution of any operations against ISIL in Syria is high….Conversely, allowing involvement is a genuine and valued contribution to the relationship…'

Contributing to the relationship" doesn't sound to me like an assessment of any relevant consideration under s.51.

In his first press conference after his election victory in October 2015, Justin Trudeau announced that Canadian fighter jets would withdraw from US missions against Islamic State. Perhaps Trudeau accepted the 2014 view of the Canadian Minister of Foreign Affairs that (emphasis added):

[T]he democratically elected government of Iraq has asked the world for assistance and has asked Canada to participate. This initiative has obviously been before the United Nations Security Council, where the Prime Minister showed great leadership by speaking, as I did at a previous Security Council meeting, in the last two weeks. It obviously has the blessing of both the UN Security Council and the government of Iraq. We do not have any legal authorisation in Syria. As despicable as the political leadership is in Syria, and with respect to the motion before Parliament, we obviously do not have any legal basis at this stage for that effort.

No such announcements were forthcoming by the then 'moderate' Prime Minister Turnbull.

Now, just a few years down the track, we have seen the images of some of the heartbreaking carnage wrought by the fighting in Syria – human suffering on a grand scale, rotting corpses in the streets, the bodies of small children washed up on foreign shores after fleeing the insufferable conditions in their country, and an ancient birthplace of civilisation reduced to rubble.

Make no mistake: we unlawfully invaded a sovereign State to contribute to that. Both the Coalition Government and the lacklustre Opposition are complicit. Either they remain ignorant of the illegality, and in my view immorality, of their actions, which is hard to accept, or they choose to put the issue to one side while pursuing some agenda we aren't told about, like "contributing to the relationship". Consistent with the lack of open debate in Parliament before such measures are taken, the redactions of the FOI documents about why the Government chose to do what it did make it clear that the Government doesn't want us to know. By shutting the door of openness and transparency – which seems to have become the norm on many contentious domestic and foreign policy issues – they seek to deprive us of our right to examine and hold them accountable for what they do.