Why didn't Canada just send the migrants back?

As hundreds of illegal Tamil immigrants stepped ashore for the first time in three months and requested asylum, many Canadians were asking: Why didn't the government simply turn the boat back?

Instead, a navy vessel smoothly escorted the freighter to dock near Victoria on Friday, ushering passengers to shore for investigation and to assist them with their health and safety needs, even while Ottawa maintained some of them were "suspected human smugglers and terrorists."

The next home for most of the 490 people will be in Vancouver-area detention centres to await scrutiny on their identities for national security reasons.

Migration experts say sending the ship away would have violated international law, and that's why Ottawa now appears to be seeking other channels to prevent further ships setting their sights here.

Still, those options are limited.

Even if blocking a ship's entry was permitted, there'd be other factors to consider, said Scott Watson, assistant professor of international relations at the University of Victoria.

"Let's say if they didn't have enough fuel, or if there was not enough food or water on board," he said. "At some point there is a moral or ethical responsibility to say we can't simply send them away."

Canada is obliged to not return people to their home country if they face persecution there under an agreement signed in 1969 that's set out in the United Nations 1951 Refugee Convention and 1967 Protocol. The decision came in the aftermath of the Second World War, a result of the consequences faced by thousands of Jewish people who tried to flee Germany but were refused entry by other countries.

Far more asylum seekers actually arrive in Canada by plane and land-crossing each year to claim refugee status than by perilous sea journey, but they don't usually turn up on the public radar, Watson said.

"There's certainly that dramatic fashion about a boat arrival that seems to stir up a dramatic response in the way that other types of arrivals simply don't," he said of the public's current opinionated reaction, with some people bluntly suggesting the migrants aren't wanted here.

Public Safety Minister Vic Toews has repeatedly said those among the group found guilty of criminal acts will be prosecuted. But he hasn't elaborated on how the government will deploy a preventative crackdown -- one aimed at human smuggling.

Canadian authorities say they knew for more than two months the ship was coming. Still, Canada didn't have the legal authority to board the MV Sun Sea in international waters to arrest suspected terrorists. Waiting until the ship had entered Canadian territory, as it did, was the only option for the government to have full control over the legal process, Watson said.

"You'd be on pretty shaky legal ground on what you could actually charge them with and whose jurisdiction it would actually fall under" if the arrests happened at sea.

Still, Toronto immigration lawyer Lorne Waldman speculated Canada may eventually move to give its navy the power to interdict boats outside its territorial waters. The move would eliminate dealing with refugee claimants entirely.

"I think that would have huge legal ramifications," said Waldman, who represents dozens of Tamil migrants who arrived in B.C. on a similar ship last October.

Toews has hinted part of Ottawa's response will be to increase penalties for proven human smugglers as a method of deterrence.

"That obviously is one of the easiest ways to go without infringing on international refugee law," Watson said.

There's also some talk of not allowing claims from people arriving by boat at all, though that would not hold up under the UN convention, he said.

The UN has held minor talks around creating a human smuggling convention over the past decade, but there has never been an agreement, Watson added.

Queen's University law professor Sharryn Aiken wants Canada to increase its acceptance of refugees from Sri Lanka through its embassy there.

But even that poses some difficulties.

"The problem, of course, is political for Canada. We don't like to say to our 'allies' that we're accepting refugees from your country, in your country."

MP Keith Martin, who represents the riding of Esquimalt - Juan de Fuca, where the ship docked, suggests Ottawa convince the UN High Commission for Refugees to open regional processing centres for claimants from Sri Lanka to give them a legitimate, local route to apply to other countries.

"This is safe and less costly than getting on a boat," he said in a release. "It will undercut the parasitic human traffickers that are preying on impoverished people and will save lives."

Canada has responded properly and in a humanitarian way thus far, said former CSIS agent Michel Juneau-Katsuya, though he believes the country must still develop a more robust method because the MV Sun Sea isn't likely the last.

"If we don't do something and we don't demonstrate that we're going to take measures against people trying to come to Canada like this, we might open a flood in our direction."