OTTAWA -- A key piece of evidence in the robocalls legal saga is deeply flawed and should be tossed out, says a lawyer representing Conservative MPs whose election wins last year are being challenged in court.

An Ekos Research survey that suggests voter-suppression tactics were widespread in the last election cannot be trusted, lawyer Ted Frankel said Friday.

"I think common sense ought to tell us, when the stakes are this high, we can't trust a survey of anonymous people 11 months later," Frankel said.

People's memories of the calls almost certainly faded during the 11 months between the time when the poll was done and when the harassing and misleading calls allegedly occurred, Frankel said.

Given the flurry of telephone polls that occur during an election campaign, he added, it's entirely likely people might mistake one survey for another.

"To distinguish those details of whether I was called by Ipsos Reid or by a party asking me if I was going to vote, or two parties, it's a lot to expect from someone," Frankel said.

"And it's a lot to ask this court to rely on the responses ... it's impossible, I would suggest."

The Conservative legal team has spent much of the week trying to discredit the survey -- which points to signs of a targeted voter-suppression campaign aimed at non-Conservative voters during the May 2011 election -- as well as pollster Frank Graves of Ekos Research.

They have questioned Graves' donations to the federal Liberals and inconsistencies in prior court affidavits submitted as part of the case.

There was also a kerfuffle this week after it was revealed Graves -- asked to leave the courtroom during his cross-examination so lawyers could confer with the judge -- had examined the Twitter feeds of journalists who were tweeting from inside.

On Friday, Steven Shrybman, who represents eight Canadians who are challenging the election results, conveyed Graves's apology for snooping on the courtroom chat.

On the fifth day of scheduled hearings, Frankel took aim at the Ekos survey itself. The poll is being held up by the eight as a sure sign of a targeted and widespread campaign of dirty tricks that marred the election results.

Those who participated in the telephone survey could easily have rushed through it, pressing the number 1 repeatedly on their keypads, in order to qualify for the polling firm's draw for a $500 cash prize, Frankel said.

That means they could easily have mistakenly told pollsters they received a call telling them their polling station had changed and that they did not vote as a result, he continued.

Frankel also noted that several people who told Ekos they were prevented from voting also indicated they voted for a particular party -- a contradiction the lawyer held up as further proof the survey was flawed.

He urged Federal Court Judge Richard Mosley to dismiss the legal challenge.

"This case would ... open up floodgates to this kind of tactic when people are unhappy with the outcome of the election," Frankel said.

Eight Canadians -- bankrolled by the left-leaning Council of Canadians -- are challenging the results in six ridings in Federal Court, alleging the calls prevented some people from voting, affecting the outcomes.

None of the eight were actually prevented from voting.

The six ridings in question are Vancouver Island North; Yukon; Saskatoon-Rosetown-Biggar; Elmwood-Transcona and Winnipeg South Centre in Manitoba; and Nipissing-Timiskaming in Ontario.

The case is parallel to -- and unsupported by -- an ongoing Elections Canada investigation into fraudulent robo-calls, stemming from complaints that have surfaced in 56 ridings across the country.

The hearing is scheduled to end Monday.