Sen. Mike Duffy leaves the courthouse after being acquitted on all charges Thursday, April 21, 2016 in Ottawa. Duffy is suing the Senate and the RCMP for the way they handled accusations about his expenses THE CANADIAN PRESS/Adrian Wyld

OTTAWA - Mike Duffy, the Senate and the RCMP are heading back to court with the senator seeking more than $7.8 million in damages stemming from the high-profile investigation, suspension, and court case about his expenses.

Duffy filed a claim in Ontario Superior Court on Thursday that alleges his 2013 suspension by the Senate was unconstitutional and a violation of his charter rights and that the federal government is liable for the RCMP's alleged negligence in its investigation.

The claim alleges the combined actions almost brought Duffy to the brink of death and inflicted irreparable harm to his reputation, which will forever be linked to the Senate spending scandal and the political cover-up that accompanied questions about his spending.

In a statement, Duffy said he, his family, and other senators who were "unfairly targeted" have suffered stress and serious financial damage and the Senate has shown no interest in correcting what he called its unjustified actions against him.

"My civil action raises questions which go to the heart of our democracy," the 71-year-old said in his statement.

"If this action succeeds in bringing charter protections to all who work on Parliament Hill, this will be my greatest contribution to public life."

The Prince Edward Island senator landed in trouble in late 2012 when questions were first raised about housing expenses claimed against a home he had lived in for years before he was appointed to the Senate.

In October 2013, the Senate suspended him without pay for two years. Duffy's claim calls the decision "an unprecedented abuse of power" taken in the absence of any criminal charges. Those charges wouldn't arrive until July 2014, when the RCMP filed 31 counts of fraud, breach of trust and bribery against him.

In April 2016, Ontario Court Justice Charles Vaillancourt dismissed all the charges in a lengthy and dramatic ruling that said Duffy's claims weren't illegal,and that Duffy was forced to take a $90,000 payment from Nigel Wright, Stephen Harper’s then chief of staff, to pay off his politically problematic housing expenses, even though Duffy contended he had done nothing wrong.

References to Wright, Harper and the previous Conservative government pepper Duffy's 50-page claim, but they are not targets of his lawsuit. Duffy's lawyer Lawrence Greenspon said it was the decision of the Senate to suspend Duffy that caused the ultimate harm, even if the Prime Minister's Office influenced the outcome.

"If the people of Canada want to put some blame for why this is happening, I think they should direct it to the top," Greenspon said.

Greenspon said RCMP investigators failed to give Duffy a chance to respond to the allegations he faced and appeared to ignore evidence that would have proved his innocence. The claim also alleges that the force decided to go after Duffy because he was a higher-profile target than Wright and that charging Wright could have weakened the case against Duffy.

Greenspon said Duffy should have never been charged and that the actions of the RCMP and the Senate "ruined his life."

Since then, the Senate has denied Duffy's requests for help covering legal fees or refunding the approximately $300,000 in salary he lost during his suspension. The Senate also clawed back $16,995 from his salary for seven expense claims Senate officials decided after trial shouldn't have approved in the first place.

"We have someone who has been through the public grinder and been through the criminal courts and despite all of that, the Senate still refuses to try in any way to make this man whole," said Greenspon.

The Senate and government must now file a statement of defence to respond to Duffy's claims as part of a legal process that could take from two to five years, depending on whether the case goes to trial or is settled out of court.

The Senate's interim law clerk Jacqueline Kuehl said the upper chamber will not be commenting on the case until it is appropriate to do so.

"As this is a matter before the courts, we will respect the process," she said.

Justice Minister Jody Wilson-Raybould's office also declined to comment for the same reason.

News from © The Canadian Press, 2017