Guergis has filed a $1.3-million lawsuit against Harper, the Conservative party and several figures inside the Tory government alleging defamation, conspiracy, "misfeasance in public office," infliction of mental suffering and negligence.
The former minister of state for the status of women was turfed from her post and from caucus in April 2010 after a private detective went to a party lawyer with allegations mainly about Guergis's husband, Rahim Jaffer.
Harper referred the matter to the RCMP and to the federal ethics watchdog.
Now lawyers for the government defendants are arguing before Ontario Superior Court that the entire case should be dismissed, mainly because of the concepts of Crown prerogative — Harper and the cabinet's constitutionally protected ability to make decisions — and of parliamentary privilege.
Neither Guergis nor any of the government figures involved in the case were in court Wednesday.
"The argument is the prime minister, under our system of responsible government, determines who serves in the federal cabinet ... ultimately that's not justiciable," said Harper lawyer Robert Staley.
"Someone who is disappointed because they didn't get into cabinet ... can't take this to the courts. It's purely a political discussion."
The Canadian Human Rights Commission said last November it couldn't rule on a complaint Guergis had launched there because of those two protections.
But Staley went further, saying that many parts of Guergis's claim were contradictory and not based in fact, and represented an abuse of process.
For example, he pointed out that Guergis based parts of her claim on conversations within the heart of the Prime Minister's Office about which she wouldn't have had the "foggiest clue."
"This is throwing things against the wall to see what sticks," said Staley, who is also representing Labour Minister Lisa Raitt, MP Shelly Glover and Harper's principal secretary Ray Novak.
"This is as bald as you can get."
One part of Guergis's claim states that private detective Derrick Snowdy made a range of allegations against her in a conversation with party lawyer Arthur Hamilton that included accusations of involvement in extortion, fraud and prostitution.
But another section raises the possibility that Snowdy made no allegations against her, as he told a parliamentary committee in 2010, although a letter alluding to a set of allegations was sent to the RCMP by Harper's office anyway.
"This is just gibberish, it makes no sense...," said Staley. "This is just plain bad."
Staley emphasized several times that there was nothing legally wrong or malicious about the letters sent by Harper's office to the RCMP and to the ethics watchdog, outlining that they had received allegations form a third party.
"This ultimately is all about the Office of the Prime Minister receiving a complaint about a cabinet minister and having to make a decision in real time on what to do."
Guergis ran as an independent candidate in the 2011 election in her riding of Simcoe-Grey and lost.
Shortly afterward, Canada's ethics commissioner found she had broken the rules when she wrote a letter on government letterhead to a local politician about a businessman in her riding. That businessman had been in talks with Jaffer about possible transactions.
The defendants in the defamation case include Harper, Novak, his former chief of staff Guy Giorno, Hamilton, Snowdy, Raitt and her assistant Axelle Pellerin, Glover and the Conservative Party of Canada.
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