The Royal Canadian Legion is describing the government's position as "reprehensible."
The government, which intends to defend against a class-action lawsuit by veterans of the war in Afghanistan, says it's unfair to bind current and future governments to promises that date back to the First World War.
The Legion and other veterans groups have scoffed at the argument.
"There is only one veteran, whether you are 19 years of age or 105," Gordon Moore, the Dominion president of the legion, said in an interview.
Just before the Battle of Vimy Ridge in April 1917, then-prime minister Robert Borden acknowledged the government's duty to care for the wounded.
"You can go into this action feeling assured of this, and as the head of the government I give you this assurance: That you need not fear that the government and the country will fail to show just appreciation of your service to the country and Empire in what you are about to do and what you have already done.
"The government and the country will consider it their first duty to see that a proper appreciation of your effort and of your courage is brought to the notice of people at home… that no man, whether he goes back or whether he remains in Flanders, will have just cause to reproach the government for having broken faith with the men who won and the men who died."
Borden's statement has shaped decades of government policy but it has never been formally enshrined within the Constitution — a point government lawyers have exploited in their lawsuit defence.
Veterans Affairs Minister Julian Fantino underscored the position when he met with a series of veterans groups last week.
Moore said the Conservative government is trying to shed its decades-old commitment to troops who defend the country — something that could affect future conflicts.
"They have that moral obligation on behalf of all Canadians," Moore said. "I believe they're trying to slip out, but as we all know there will be an election within (two years) and there's a lot of upset and angry people out there on how veterans are being treated."
Soldiers who served in the war in Afghanistan are suing over the new veterans charter, which they claim is discriminatory. The legislation, originally passed in 2006, provides workers-compensation-style lump sum payments to wounded vets, as opposed to the pension-for-life settlements provided after previous wars.
Joshua Zanin, a spokesman for Fantino, said the government is committed to seeing recent changes to the charter put to the test before a parliamentary committee this fall in a legislated review.
"Parliament is the appropriate forum to discuss how the government serves Canadian veterans, and the review will provide a venue where all voices can be heard including those of veterans, serving personnel, family members, other interested parties and experts," Zanin said.
But Moore said care varies widely between regular force and reserve veterans in Canada, which is why the legion is pushing for a universal standard for the wounded and injured.
The military demands something known as universality of service, which requires those who join to be ready and fit to defend the country at all times — an expectation that Moore said should be turned back on the government when it comes to caring for veterans.
In return for fulfilling their duty, all soldiers should expect the same access to care regardless of whether they are full-time or part-time, and regardless of what war they served in, he said.
"They should have 100 per cent care," Moore said.
The only exception he could see would be for reservists who serve less than 180 days a year, he added.
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