It now falls to Federal Court Judge Richard Mosley to decide whether the evidence merits the drastic step of throwing out the results of last year's federal election in the six ridings in question.
No matter how Mosley rules, an appeal is all but guaranteed. The Council of Canadians, a political advocacy group that bankrolled the court challenge, says it will appeal if a ruling comes in favour of the MPs.
If it goes the other way, the Conservatives likely won't go down without a fight.
"We certainly don't want to cut the process short," the council's national chairwoman, Maude Barlow, said outside the courtroom.
"We're committed for the long run."
The council estimates it spent around $600,000 paying the legal bills of eight voters who allege that misleading and harassing phone calls during the campaign kept some people from voting and may have affected the results.
The six ridings in question are Vancouver Island North in British Columbia; Yukon; Saskatoon-Rosetown-Biggar in Saskatchewan; Elmwood-Transcona and Winnipeg South Centre in Manitoba; and Nipissing-Timiskaming in Ontario.
Court heard a great deal of debate about the merits of an anonymous, automated survey by polling form Ekos Research that suggested non-Conservative supporters were more likely to have received harassing or misleading calls prior to the May 2011 vote.
According to the poll, as many as 6,000 voters could have had their trips to the ballot box thwarted by the phoney calls.
But Conservative party lawyers sought to cast doubt on the Ekos report. They described the poll as flawed, saying it could have yielded unreliable results that the court should not allow as evidence.
They also tried to undermine the credibility of Frank Graves, the pollster behind the report. Conservative party lawyer Arthur Hamilton repeatedly questioned Graves' donations to the federal Liberals and inconsistencies in prior court affidavits submitted as part of the case.
At one point, Graves — who had been asked to leave the courtroom during his cross-examination so lawyers could confer with the judge — was found to have scanned the Twitter feeds of journalists tweeting from inside, a jurisprudential no-no.
Steven Shrybman — the lawyer acting for the eight complainants — apologized on Graves's behalf. In Monday's closing arguments, however, he defended him as a reliable and unbiased pollster.
"It's an awful allegation, it's unsupported by any evidence and it simply clutters the landscape," Shrybman said.
Shrybman also sought to dispel the criticisms of the Ekos report, saying they are largely based on the conclusions of another expert who provided evidence to the Conservative legal team.
Conservative lawyers have asked the court to dismiss each of the applications. They argued the Council of Canadians has no bona-fide witnesses who could testify that the calls prevented from casting a ballot.
Indeed, none of the eight applicants actually failed to vote in the 2011 election as a result of the alleged tactics.
"It speaks volumes that despite the Council of Canadians' vigorous search and nationwide media attention, it was not able to produce a single elector to testify that he or she was prevented from voting," Conservative party spokesman Fred DeLorey said in a statement.
Shrybman maintained there is enough proof that the fraudulent calls did occur, which he argued should be enough for a judge to overturn the results. The evidence suggests that hundreds of people failed to cast ballots as a result of the calls, he said.
"Our obligation is to persuade you only on the balance of probability that there was fraud and it affected the result of the election," he told Mosley.
"We have produced ... the best evidence that could be gathered about the occurrence of voter suppression and its effect."
Mosley said he will deliver his decision at a later date — and hinted in his closing remarks that he intends to take his time doing so.
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