Prime Minister Stephen Harper's attempt to have the lawsuit against him by his former cabinet member Helena Guergis dismissed will be up for debate in an Ottawa courtroom today.

Lawyers for Guergis, Harper and numerous other defendants, including Labour Minister Lisa Raitt and Conservative MP Shelly Glover, will argue whether the lawsuit should be allowed to proceed. The hearing is scheduled to begin at 10 a.m. ET.

Guergis filed in December a lawsuit that makes claims of conspiracy, defamation, misfeasance in public office, negligence and infliction of mental suffering.

The former Conservative MP, who stepped down from cabinet amid controversy in April 2010 and was removed from caucus, is suing for general damages of $800,000 plus punitive damages of $250,000 and aggravated damages of $250,000.

Guergis was the minister of state for the status of women and the MP for Simcoe-Grey in Ontario. After the controversy, she was not allowed back into caucus or to run again as a Conservative candidate.

She is not only suing her former boss and caucus colleagues, but also:

Guy Giorno, Harper's former chief of staff.

Ray Novak, Harper's principal secretary.

Arthur Hamilton, the Conservative Party's lawyer.

Cassels Brock & Blackwell, Hamilton's law firm.

The Conservative Party of Canada.

Derrick Snowdy, the private investigator who helped spark controversy around Guergis.

Axelle Pellerin, a former staff member with Raitt.

Harper filed a motion in court in early May to have the lawsuit dismissed, claiming that Guergis has "no reasonable cause of action." It was also filed on behalf of Raitt, Glover and Novak, and Giorno also filed a similar motion.

The motion says Guergis's claims are not subject to the judicial process but relate instead to matters of Crown prerogative and parliamentary privilege. In other words, decisions about who is allowed in cabinet and in the caucus and who is allowed to run as a candidate for a political party are not matters for the court to decide.

Guergis claims that Harper, Novak and Giorno defamed her in a letter they were involved in sending to the RCMP regarding allegations they said they were made aware of by Hamilton, who was made aware of them through Snowdy.

She also alleges that the defendants engaged in a conspiracy and unlawful acts in order to remove, or justify her removal, from her political positions. She claims that their actions resulted in damage to her reputation, her health, and her ability to earn an income.

The allegations, according to the RCMP letter, include fraud, extortion, obtaining benefits by false pretences and involvement with prostitutes. They allegedly related to the conduct of Guergis and her husband Rahim Jaffer, who is also a former Tory MP.

Harper said in the letter that he had no first-hand knowledge of the allegations, and in her statement of claim, Guergis denies all of them.

Probes into the allegations by the RCMP and Parliament's ethics commissioner both cleared Guergis.

Lawsuit is solid and should proceed

Harper's motion to halt the lawsuit in its tracks also says that when he publicly spoke about the allegations, he did not defame her and that any alleged conversations about the RCMP letter or Guergis's conduct would be protected by the doctrines of absolute and qualified privilege.

In response to Harper's effort to dismiss the lawsuit, Guergis says in court documents that his motion should be defeated because he hasn't shown beyond doubt that she can't succeed with her lawsuit. In a factum filed with the court last week, Guergis rejects the arguments put forward in Harper's motion, but says if it succeeds, she wants the court to allow her to amend her original lawsuit.

She maintains that her statement of claim is a concise statement of the facts and complies with the proper legal tests for the claims made in her lawsuit.

"It doesn't contain any statements that are irrelevant, argumentative, inserted for colour or that constitute bare allegations that should be struck out," the document says.

Harper's office would not offer a comment Tuesday, saying the matter is before the courts, and Guergis's lawyer also declined to comment. The hearing is scheduled for two days.

When Guergis left cabinet — she says she resigned under duress — she sat as an Independent MP. She ran as an Independent candidate in the May 2011 election and lost.

Read Meagan Fitzpatrick's liveblog from court: