Mike Duffy's trial on fraud, bribery and breach of trust charges enters its final phase today, with Crown and defence lawyers set to wrap up the case with closing arguments.

In just days, the fate of the former high-profile broadcaster and Conservative senator will be in the hands of a judge, whose ruling could have major consequences for other senators — and for the upper chamber itself.

Donald Savoie, a public administration expert at the University of Moncton, said the stakes are high for other senators whose expense claims were referred to police by the auditor general.

The Duffy decision could set a precedent for other senators in trouble.

"I suspect the RCMP is playing a wait-and-see on how the judge comes down," Savoie told CBC News. "If the judge comes down with a not-guilty verdict, then I think it will have an impact. If they can't make this one stick, then how could they make the other ones stick?"

Nine other files sent to RCMP

Last June,  Auditor General Michael Ferguson referred the files of nine retired and sitting senators to the RCMP after carrying out a two-year review that flagged more than $975,000 in questionable housing and travel claims.

Savoie said the outcome of Duffy's case has potential to further erode the credibility and reputation of the Senate as a whole.

"The Senate has been in a downward slide for some time, not just with the Mike Duffy trial," he said. "This adds another layer to it. It will not help an institution that is already in great difficulty.

"If he's found guilty, it's going to hurt it even more. If he's found not guilty, it's still the aura of what the Senate has gone through in the last few years."

Duffy has pleaded not guilty to 31 charges of fraud, breach of trust and bribery related to expense claims and office budgets.

In all, the court heard 60 days of sometimes conflicting testimony from members of the political elite, forensic accountants and backroom Senate staffers.

Duffy also testified for eight days as the defence's only witness.

When the trial opened nearly one year ago, it was billed as one of the most sensational political court cases in recent Canadian history and attracted a great deal of media attention.

Interest has waned considerably with the Conservatives no longer in power. But University of Ottawa law professor Penny Collenette says there are still political stakes at play.

Danger for Conservatives

"The danger for the Opposition is that everyone will be reminded that this mess happened on their watch," she said.

"The challenge for the government is that it is tough to get on with a Senate of the future while people are focused on the Senate of the past."

While there is now opportunity to turn the page with new appointees, Collenette said if Duffy is acquitted and returns to the Senate, it could become an even more "dysfunctional" workplace.

Duffy is now on a paid leave of absence from the upper chamber.

If he is found not guilty, he can return to his job with full salary and office resources. But if he is found guilty of even one of the charges, he faces automatic suspension without salary and resources — and possible imprisonment.

Donald Bayne

Donald Bayne, defence lawyer for suspended senator Mike Duffy, can be expected to rigorously cross-examine Nigel Wright beginning Thursday. (Sean Kilpatrick/Canadian Press)

A suspension from the Senate would remain in place even if he appeals his conviction.

Before his trial adjourned before Christmas, Duffy submitted an ethics disclosure form to Senate administration. That "public disclosure summary" must be filed annually to comply with the Senate ethics officer — a requirement if he were to reclaim his seat.

Crown prosecutor Mark Holmes is expected to kick off closing arguments today at 10 a.m. ET before Judge Charles Vaillancourt in an Ottawa courtroom.

He will recap the Crown's case: that Duffy broke the law by funnelling ineligible expenses for services such as a fitness trainer, a makeup artist and photo-framing through Senate subcontracts with his longtime friend, Gerald Donohue; by claiming expenses for trips that weren't made for Senate business; and by claiming Prince Edward Island as his primary residence instead of Ottawa.

Duffy Trial 20150814

Nigel Wright, former chief of staff to Prime Minister Stephen Harper, was among the high-profile witnesses who testified at the Mike Duffy trial. (Fred Chartrand/Canadian Press)

The bribery charge relates to the $90,000 cheque from Nigel Wright, Stephen Harper's then-chief of staff. It was cut to repay some of the questionable expenses that were becoming a growing political problem.

Senate rules 'vague'

Duffy's lawyer, Donald Bayne, will then take his turn to sum up the key line of defence: that the claims and actions were perfectly legitimate under vague Senate rules and that Duffy did not break the law.

One parliamentary expert believes the public has grown weary of the trial and that the verdict will have little interest or impact, whatever way it goes.

"This was an important political event when the Conservatives were in office because if it came out that Mr. Harper lied to Parliament, it would have provoked a political crisis and probably forced him to resign," said Gary Levy, who has written and lectured extensively on parliamentary democracy.

"With the change in government, this is now just a tawdry story about a guy who is alleged to have cheated on his expenses. I think the verdict will have little further consequences on the Senate."