A group of disabled veterans is taking its legal fight for better pensions to the Supreme Court of Canada.

The six veterans involved in what is called the Equitas case say the federal government has a sacred obligation to care for the country's wounded soldiers, and that the duty was breached in a 2006 overhaul to the compensation regime for those injured in the line of duty.

Mark Campbell, a retired major, and former combat engineer Aaron Bedard, both part of the Equitas suit, held a news conference on Parliament Hill today to announce plans to take their pension fight to the Supreme Court.

Campbell said it's a "national disgrace" that the government is spending tax dollars in a legal fight against injured veterans, and "untolerable" that changes to the pension regime have left two standards of compensation for soldiers, depending on when they were injured.

"This is grossly unfair and it has to change," he said.

The overhaul replaced lifelong disability pensions with a lump-sum payment, career training and targeted income support, which the veterans claim was worth less than the previous pension system.

The case, which they hoped to turn into a class-action lawsuit, has been winding its way through the courts since 2012. It was launched when the Conservative government was in power but continued under the Liberals.

Last year the B.C. Court of Appeal struck down the veterans' claim.

Retired Major Mark Campbell says he and other veterans have filed with the Supreme Court seeking an appeal on a decision which struck down claims of inadequate compensation for war wounds suffered in Afghanistan. 2:06

Lawyer Don Sorochan, who is representing the Equitas group, hopes the Supreme Court will hear an appeal to that decision, and definitively rule on whether the government has a "social covenant" or sacred obligation, and whether it is enforceable.

"The position taken by the government was astonishing. For them to stand up and say we don't have any special obligation to veterans was completely contrary to everything they had been saying in Parliament, on the election campaign," he told CBC News.

During the 2015 federal election campaign, the Liberals promised to give veterans the option to have a lifelong pension.

Major changes announced

After much frustration and protests, the government announced major changes to the compensation system in December 2017 that would pour about $3.6 billion into veterans' benefits.

But Campbell called that proposal a "sham."

"The new pension for life is nothing more than a shell game," he said.

Questioned about the legal challenge in the House of Commons today, Veterans Affairs Minister Seamus O'Regan said the government has spent $10 billion to expand: pain and suffering compensation, income replacement and education, career transition and mental health benefits.

He also said the government has followed through on its pledge to institute a life-long pension.

"Veterans asked for a pension for life option. We delivered," he said.

According to a copy of the court filing to the high court, the case raises "fundamental questions about the unique and special relationship between Canada and members of the Armed Forces," and whether an "inadequate compensation scheme" breaches Canada's solemn obligation to those who served the country.

'Profound implications'

The filing says the B.C. Court of Appeal's decision could have profound implications for future military service in Canada and the very operation of Veterans Affairs Canada.

"Those who enlist in military service do so at great personal risk and sacrifice, but do so based on the premise which underlies the social covenant: Should they fall or be injured, the nation and people of Canada will ensure they will be looked after," the filing reads. "The implication of the Court of Appeal's decision is that this solemn obligation does not exist."

Veterans advocates say the government's new pension regime for injured veterans is grossly unfair. (CBC)

Sorochan said the social covenant has been recognized since the First World War, when promises were made to those who served their country. It was, and remains, necessary to build and retain a voluntary citizens' army.

Sorochan said the B.C.appeal court ruling effectively said even if a promise was made, any government could undo it "on a whim."

"I don't think that's much comfort if you're going to put your life on the line when you could take away the promise."

Phil McColeman, the Conservative veterans' affairs critic, called on the Liberals to fulfill their campaign promise.

"It's shameful that as a result of Liberal broken promises, veterans have been forced to take their case to the Supreme Court in order to be heard," he said in a statement to CBC News. "The Conservative Party of Canada believes in providing the best possible services and benefits for veterans and their families, in recognition of their service to Canada."

In the House, O'Regan said when the Conservatives were in office, members of the armed forces returned home from duty to find services cut, veterans offices closed and their voices ignored.

In a news release, Marc Burchell, president of the Equitas Society, said the B.C. Court of Appeal ruling says there is nothing embedded in the law to protect injured veterans.

"This case is about making sure the government of Canada supports our fighting men and women as they must," he said. "The government must either reinstate the old Pension Act, or must make sure compensation for injuries under the New Veterans Charter is as good as – or better – than what they received before."