Lawyers behind a court bid to block a massive sale of weaponized fighting vehicles to Saudi Arabia argued in Federal Court on Monday that Foreign Affairs Minister Stéphane Dion ignored serious human-rights violations in favour of preserving jobs when he authorized the export of these machines in April.

A $15-billion deal – the largest advanced manufacturing export contract in Canadian history – has landed before a federal court judge in Montreal who must decide whether the law demands she place human rights above politics and a huge industrial benefit.

The Harper government brokered the deal, but it was Prime Minister Justin Trudeau's government this spring that approved the export of the combat vehicles despite Canadian arms-control rules warning about sending weapons to human-rights abusers.

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The vehicles are to be equipped with medium-gauge machine guns or anti-tank cannons.

A lawyer representing Ottawa countered that not just human rights factor into the decision, but also economic fallout, national security and politics. And even if Mr. Dion had ignored human rights, he was well within his powers to issue export permits based on his vast ministerial discretion, federal lawyer Bernard Letarte said.

Mr. Dion signed the export permits for the vehicles in early April – meaning the Liberal government has taken full ownership of the decision, which they once said they were unable to stop.

In a Montreal courtroom, Justice Danièle Tremblay-Lamer heard arguments over a motion by law professor Daniel Turp to quash an export permit signed by Mr. Dion, in which his legal team argued human rights should trump other considerations.

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The justice's only commentary in the hearing was to point out twice that a country has many avenues to influence human rights abroad – not just by restricting arms sales.

André Lespérance, a lawyer for the petitioners trying to block the sale, said selling armoured vehicles with armour-piercing cannon and machine guns runs contrary to whatever else Canada may be trying to do to promote human rights with Riyadh. "To give arms to a country that uses them to violate human rights is to contribute to that violation," said Mr. Lespérance, who was once a federal lawyer. "It's beyond willful blindness."

Mr. Letarte said there is no proof Saudi Arabia uses armoured vehicles to break international humanitarian law. But the question is not even relevant, he added.

"It's not appropriate to re-litigate the facts behind this decision," he said. "It's not up to the court to substitute its judgment for the minister's. Human rights are something the government takes into account in the way it feels is appropriate.

"The question belongs to the Foreign [Affairs] Minister."

On May 11, 2016, The Globe and Mail reported on video evidence of armoured vehicles being used to suppress protests in Saudi Arabia's Eastern Province.

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The combat vehicles in the videos are not Canadian-made, but they demonstrate the regime's inclination to use such military assets against its own people in a region that is very difficult for Canada to monitor.

Mr. Lespérance represents Mr. Turp – a Quebec law professor, retired Bloc Québécois and Parti Québécois politician and occasional litigant who has taken the federal government to court over potential participation in the Iraq war, the handling of detainees in Afghanistan, and the Conservative government's decision to withdraw from the Kyoto climate change protocol.

He admitted his case faces difficult hurdles.

"The challenge is we are in international affairs and the courts have traditionally been reluctant to get involved," he said.

By the end of the 2015 campaign, Mr. Trudeau was calling the combat vehicles jeeps. Mr. Lespérance repeatedly referred to them as tanks on Monday. They fall somewhere in between, but are decidedly closer to tanks, with their armour, all-terrain capability and heavy firepower.

If they are delivered before the end of the conflict, the armoured vehicles are likely to be used in Yemen, where Saudi Arabia is taking part in a coalition aimed at stopping Iranian-backed rebels.

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The $15-billion contract will support thousands of jobs in Canada at a General Dynamics Land Systems Canada plant in London, Ont., and suppliers across the country.

Saudi Arabia, which regularly ranks among the "worst of the worst" for human rights on U.S. watchdog Freedom House's annual list, has been accused by a United Nations panel of violating international humanitarian law with repeated strikes that have killed civilians in neighbouring Yemen.

The hearing in Federal Court continues on Tuesday.