There is no constitutional requirement for Prime Minister Stephen Harper to recall Parliament to discuss Canada's potential role in a military strike against Syria, but recent practice suggests he should reconvene the House soon, particularly since Canada is likely to be involved in some way, even if just to declare its support.
The right to declare war or send troops overseas is a cabinet prerogative in parliamentary tradition, but government practice has varied widely over the decades. Sometimes, as in the decision to declare war on Germany in 1939, Parliament's approval was sought, although it was not consulted in the declaration of war against Japan and other belligerents in the Second World War.
The Liberal government declined to consult Parliament in advance of the Korean War, but take-note debates were held on Kosovo and the decision to participate in the war in Afghanistan in 2001.
Mr. Harper held two votes on whether to extend the mission in Afghanistan, first in 2006 and again in 2008.
Parliament's only power to influence war-making decisions is the ability to ask questions, demand answers and even withhold funds, which isn't a real possibility if the government enjoys a majority.
The decision on whether to hold a vote, a debate or act alone has usually been determined by political considerations, such as when Mr. Harper held a private meeting with Opposition leader Thomas Mulcair last January on whether to extend the deployment of a C-17 cargo plane in support of France's counter-insurgency in Mali.
Such a meeting wasn't required, but it was good politics and sound practice to involve parliamentary leaders in decisions of war and peace.
Mr. Harper was planning to prorogue Parliament before its scheduled return on Sept. 17, so it would be a simple matter for the government to convene for a take-note debate next week.
Mr. Muclair, who has been demanding Parliament be recalled, obviously has unanswered questions he wants to put to the prime minister in public. He should be given that opportunity because the implications of an attack on Syria are serious.
Canada should support the U.S.-led coalition that is assembling to punish President Bashar Assad for the use of chemical weapons against his own people.
The goal would not be regime change, but to protect Syrian civilians from further attacks and enforce international laws that prohibit the use of chemical weapons. An attack is also justified under the doctrine of Responsibility to Protect, which obliges law-abiding nations to come to the aid of people who are being slaughtered by their own governments.
Such an intervention is not without risks. It could prolong the civil war, resulting in still more deaths, or it could tip the balance in favour of the rebels, including groups that are not necessarily friendly to the West. Relations with Russia and China, which oppose intervention, could be dealt serious setbacks, while terrorist activities around the world could escalate.
There is also the possibility, of course, that it would end quickly with the degradation of Syria's ability to attack its own people with chemical weapons, which is the optimum goal.
Canada does not have much to offer in such a conflict, but it could provide refuelling and cargo aircraft, as well as naval support.
There are never good options when deciding how or whether to intervene in the messy affairs of failing states or murderous dictatorships that pose a threat to peace and their own people, but this is not a case where the world can avert its gaze.
Too many innocent people are dead, maimed, dislocated or homeless.
Canada's allies are going to act, and Parliament can play its role by joining the coalition of the outraged.