On the eve of his last day on the job, Parliamentary Budget Officer Kevin Page is taking the government to Federal Court to argue his right to access documents and data relating to last year's budget.

Page is also asking the court, which is hearing his case beginning Thursday, to clarify his office’s mandate.

Page’s challenge was prompted when NDP Leader Thomas Mulcair asked his office to analyze whether the savings outlined in the 2012 budget are achievable and whether they would have a long-term fiscal impact. Frustrated by the inability to retrieve documents to investigate Mulcair’s request, Page turned to the court after unsuccessfully issuing several deadlines to government departments to hand over data.

Page is also seeking the court's opinion related to statements made last summer by Finance Minister Jim Flaherty, and echoed by Foreign Minister John Baird and Treasury Board Secretary Tony Clement, that Page was exceeding his mandate.

"He's asking for information about money that's not spent, which is a very odd thing for the parliamentary budget officer to ask," Flaherty said again in October. "His mandate is to review government spending, not to review spending that was reduced."

In court Thursday, Page's lawyer, Joseph Magnet, told Justice Sean Harrington of the Federal Court that Page was trying to clarify whether he is entitled to ask the government for detailed spending plans, but was not asking the court to grant any sort of remedy.

One of the points being argued is whether the Federal Court even has the jurisdiction to hear Page's case, or whether this is a political, not a legal matter, that Page should take to the House of Commons. However, one observer in court noted that it might be difficult for Page to make his case to Parliament, when the majority of MPs are Conservative.

Replacement 'is a mistake'

Page, who retires Friday, told host Evan Solomon of CBC News Network's Power & Politics he thinks the interim replacement for his position, Parliament's chief librarian, Sonia L’Heureux , is a bad choice because, although she is "a good manager in the library," she has no experience.

"We have experienced people in my office," Page told Solomon. "People that have worked on budgets in the past, have run big parts of the Department of Finance, have steered budgets through Privy Council Office, and these people have the moral authority and the experience to lead."

Page added, "It sends a very bad signal that they [government] are not interested in the Parliamentary Budget Office we've had in the past five years," adding he thinks the government is trying to "disentangle" the PBO.

Mulcair, who is named as a respondent in the case, told reporters in the foyer of the House of Commons Wednesday that during his recent trip to Washington he met with Page's counterpart, the head of the U.S. Congressional Budget Office.

"It's an extraordinary government institution, with a couple of hundred employees, a budget in the tens of millions of dollars. Despite the fact that there's a highly partisan atmosphere in Washington, everyone respects the institution. That's what's sorely lacking with the Conservatives," Mulcair said.

He went on to say, "Stephen Harper does not tolerate anyone telling him what he doesn't need to hear. Same thing with Kevin Page, Kevin Page was simply too strong and capable for Stephen Harper to tolerate. That's why he wants to get rid of Kevin Page. That's why he wants to kill the institution."

Five-year term over

"It's irony," Page told the CBC's Anna Maria Tremonti on CBC Radio's The Current Wednesday, referring to the fact that the two-day long court case is beginning just as he leaves the job. Page is retiring after serving a five-year term.

Page outlined how he thinks the process should work: spending plans from each government department should be provided to committees and members of Parliament who would scrutinize those plans and debate the effects of service levels. "Instead we have no plans," he said. "Even one year after budget 2012, we have no austerity plans in front of members of Parliament. Yet we ask MPs to approve these authorities. It's wrong."

Paul Champ, the lawyer representing Mulcair, said it was the Conservative government that passed the law creating the Parliamentary Budget Office. "It was in the wake of the Gomery Inquiry," he said. "This was one of this government's first bills, back in 2006, the Federal Accountability Act. It was a major [policy] plank — of increasing transparency in government and ensuring oversight of government spending. It's really unfortunate we're here years later and one of the key innovations of budget estimates and spending is now being frustrated by government."

Page said, "The power of the purse rests with individual MPs in the legislature, which includes backbencher Conservative members. They need to hold cabinet ministers, the executive, to account. If they don't have spending plans, they cannot do that job."

Deliberately chose hot button issues

Page told Tremonti that during his tenure as parliamentary budget officer, he deliberately chose hot button issues to investigate, such as the cost overruns in the F-35 fighter jet procurement program, or his conclusion that the Old Age Security program was in fact sustainable, contrary to the government’s claim.

He had been a career civil servant for over 25 years, he told Tremonti, acknowledging what he calls "a culture of secrecy" within the public service.

But he realized the Parliamentary Budget Office would be his last civil service position since he was nearing retirement age. When he began his tenure, he said, "a parliamentarian" asked him to decide if he wanted to be useful or useless.

Although Page describes himself as someone who "adds and subtracts numbers for a living," he said it was important to him to consider "our kids, the next generation."

Arguing against Page Thursday in Federal Court will be the Speakers from both the Commons and the Senate, and the attorney general. Their submissions will be based on the opinion that it is Parliament and not the courts that should decide on the PBO's mandate.

Mobile-friendly version of Leslie MacKinnon's liveblog from court also available.