Montreal, Canada - Amid vigils, fundraisers and an outpouring of public support, Canada has emerged as a leader in international efforts to seek justice for the victims of last week's deadly Ukrainian plane crash in Iran.

"The families of the victims and all Canadians want answers. I want answers. That means closure, transparency, accountability and justice - and this government will not rest until we get that," Justin Trudeau said on January 9, a day after the Ukrainian Airlines flight went down near Tehran. All 176 people on board Ukraine International Airlines flight PS752 were killed, including 57 Canadian citizens.

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Speaking to victims' families on Sunday, Trudeau reiterated his promise to pursue "justice and accountability". But according to legal and political experts, without the results of a thorough investigation, it remains unclear what justice may look like, and the search for answers may be complicated for Canada by the tense political climate.

Mourners attending a memorial for the victims of the Ukrainian passenger plane which was shot down in Iran, in Toronto, Ontario, Canada [Carlos Osorio/Reuters]

"Canada is to an extent at the mercy of the Iranian authorities to be able to enter the country, to be able to access the crash site, to be able to get as much information as possible," said Amanda Ghahremani, a lawyer who specialises in international criminal law, access to justice and redress for victims of atrocities.

As a result, the Canadian government must tread carefully to ensure "that the victims and the victims' families have access to the truth … to justice, and … to some form of reparation".

"There's still so much that we don't know," she told Al Jazeera.

First step: Diplomacy

After initially disputing reports that an Iranian missile struck the airliner, Iran admitted that its military mistakenly shot down the Ukrainian International Airlines flight.

Iranian Foreign Minister Mohammad Javad Zarif said the fatal incident was the result of "human error" at a time of heightened tensions between Iran and the United States. Several people have been arrested, Iran said on Tuesday.

The plane crashed shortly after Iran launched missiles at American targets in Iraq in retaliation for the US assassination of top Iranian military commander Qassem Soleimani.

A sad day. Preliminary conclusions of internal investigation by Armed Forces:



Human error at time of crisis caused by US adventurism led to disaster



Our profound regrets, apologies and condolences to our people, to the families of all victims, and to other affected nations.

💔 — Javad Zarif (@JZarif) January 11, 2020

An investigation is underway in Iran, with international experts from several countries allowed in to provide technical assistance in the probe.

"It is vital that the investigation that is underway right now be fully independent, be transparent, be thorough, be comprehensive," said Alex Neve, executive director of Amnesty International Canada, adding that the avenues people take to get justice would depend on what the evidence shows.

The Iranian government is not known for opening itself up to such probing, Neve told Al Jazeera, so "it's going to be really crucial for governments … to stay very vigilant around the nature of the investigation".

So far, Canada's Transportation Safety Board (TSB) has said Iran indicated that Canada will be able to play a more active role than international rules require in the investigation.

Transportation Safety Board Chair Kathy Fox speaking during a news conference in Ottawa, Ontario, Canada [Blair Gable/Reuters]

But TSB head Kathy Fox said on Monday that the body does not "yet fully know what the scope of our role will be".

Iran taking responsibility for the crash is important, Ghahremani said, and may have legal ramifications going forward.

Under international law and specific aviation conventions, the victims' families may have access to a range of options in their pursuit for justice, including claiming compensation from the airline, or, under very specific circumstances and pending the results of the investigation, making a claim against Iran in Canadian court.

Canada can also appeal to the United Nations' top court, the International Court of Justice, to try to hold Iran accountable.

But Ghahremani said the first and best step is meaningful diplomacy.

"Engaging with Iran and trying to negotiate some type of compensation settlement for the victims would be the most important and most immediate avenue," she said.

"It's only as a last resort, when those discussions fail, that Canada would have to resort to legal procedures. But if there's a way to avoid such a lengthy and costly legal process through diplomacy and negotiations… then, I think that would be really helpful for the families."

Complicated relationship

The fact that Canada and Iran do not have formal diplomatic ties, however, will likely only complicate matters, experts said.

Relations between the two countries broke off in 2012 when Canada's then-Prime Minister Stephen Harper expelled Iranian diplomats from the country and shuttered the Canadian embassy in Tehran. At the time, Ottawa denounced Iran as "the most significant threat to global peace and security in the world" and placed it on a list of state sponsors of terrorism.

Working to re-establish relations with Iran was one of Trudeau's 2015 election campaign promises, but the prime minister suspended those efforts in June 2018 over several points of contention.

Canadian Prime Minister Justin Trudeau speaking during a memorial service at the University of Alberta for the victims of the Ukrainian passenger plane that crashed in Iran, in Edmonton, Alberta, Canada [Candace Elliott/Reuters]

"It was a terrible mistake to close that embassy, and frankly, it was a mistake on the part of the current government not to have pursued more actively the re-opening of diplomatic relations," said Allan Rock, a former Canadian minister of justice who now teaches at the University of Ottawa's Faculty of Law.

Rock said not having an embassy in Tehran creates an impediment to Canada providing consular services to the victims' families and negotiating directly with the Iranian government about things such as the repatriation of the victims' remains for burial in Canada, among others.

"Not having an embassy there means that we have to work through interlocutors like the Swiss or the Italians. It means we have to communicate indirectly with the Iranian government. It just makes things so much more difficult," he told Al Jazeera.

Chance for cooperation

The lines of communication between Canada and Iran appear to be open so far, however. Trudeau spoke with Iranian President Hassan Rouhani about the incident, while Canadian Foreign Minister Francois-Philippe Champagne spoke with his counterpart, Zarif.

On Friday, Champagne announced the creation of an international working group to share information and coordinate a response to the crash that includes representatives from Ukraine, Sweden, Afghanistan and the United Kingdom.

They will meet in London on Thursday to discuss what happened, Champagne said.

We have convened the first in-person meeting of the International Coordination and Response Group on Thursday at Canada House in London. @VPrystaiko @AnnLinde @IdreesZaman @DominicRaab — François-Philippe Champagne (FPC) 🇨🇦 (@FP_Champagne) January 13, 2020

"Canada is working with allies to ensure a thorough and credible investigation to uncover the complete circumstance that led to this terrible tragedy," a foreign affairs ministry spokesperson told Al Jazeera in an email. Canada is also providing technical assistance and expertise to Ukraine in "aircraft design, maintenance and flight operations", the spokesperson said.

Iran has also allowed Canadian officials into the country to provide support to the families of the victims.

On Monday evening, Champagne tweeted that Canadian consular officials were in Tehran.

Update on #PS752.



Our consular officials are in place in Tehran. Families of victims can reach the Standing Rapid Deployment Team (SRDT) in Iran at at +98 905 778 9710 or at sos@international.gc.ca. https://t.co/Gk7RtGcwkt — François-Philippe Champagne (FPC) 🇨🇦 (@FP_Champagne) January 13, 2020

These are welcome signs, Rock said.

He added that the tragedy - and the cooperation shown around the investigation thus far - can serve as an opportunity for Canada and Iran to resume discussions about re-establishing formal diplomatic relations.

"We have to decide what our priority is, and it seems to me, given the state of cooperation of Iran at present … we should focus on investigation, not litigation, and also quietly try to renew diplomatic relations like any mature country would do."