A lawyer for the Attorney General of Canada is citing an old court challenge Stephen Harper launched as a private citizen as precedent for stopping an injunction seeking to stay some sections of the Fair Elections Act before this fall's federal election.

Government lawyer Christine Mohr cited the 2004 case in which Harper, then president of the National Citizens Coalition, attempted to get an injunction on the restrictions against third-party spending in elections.

The attorney general is fighting an attempt by the Canadian Federation of Students and the Council of Canadians to get an injunction against key provisions of the new Fair Elections Act.

Mohr, responding to Thursday's testimony that failure to grant the injunction would lead to irreparable harm if voters aren't allowed to vote, said allowing voter information cards to be used as valid ID at the polls could lead to fraud and detract from public confidence in the electoral system.

"In Harper [vs. Canada], evidence was brought forward about irreparable harm," Mohr argued, while adding the court found the alleged harm "did not outweigh the upholding of the law."

She also argued it was "extraordinary" for a court to suspend a law without thoroughly examining its merits — and granting injunctions with respect to elections "has never been done."

The Fair Elections Act was hotly debated in Parliament before it became law in June of 2014. The applicants in this court challenge have claimed the law is a continuation of past Conservative voter-suppression tactics.

But Mohr told the court the law addresses concerns of voter fraud that all parties have been seeking to eradicate.

"If one person votes illegally," argued Mohr, "that cancels my vote."

Mohr also insisted in her argument the new law will not disenfranchise students, the homeless, aboriginal people or seniors — parties the applicants have contended are vulnerable to being hindered from voting under the law.

She told the court that if an individual shows up to vote without a driver's licence or without ID that validates who he or she is, there is nothing stopping that person from going home to get dozens of other choices of identification that fulfil the requirements.

The applicants want the chief electoral officer to have the freedom to reinstate the voter information card as acceptable proof of residence and have argued the Harper government is trying to bring in U.S.-style voter suppression tactics to hinder would-be voters who aren't likely to support Harper's re-election.

Steven Shrybman, the lawyer representing the Canadian Federation of Students and the Council of Canadians, said the chief electoral officer, the person responsible for "guarding the integrity of the electoral process," wants to expand the use of voter information cards as proof of residence across the country, but the Fair Elections Act prevents him from doing so.

In his rebuttal to the attorney general, Shrybman argued that the research of one of his experts — former B.C. chief electoral officer Harry Neufeld — was twisted by those creating the Fair Elections Act to suggest that voter fraud is widespread. To the contrary, he said, in 33 years of election administration, Neufeld found that "voting fraud which involves persons deciding to impersonate someone else, or find some other way to vote more than once, is extremely rare in this country."

Justice David Stinson said he will hand down his decision by July 20. If an injunction is granted, it would give the chief electoral officer the discretion to allow voter identification cards as proof of residence, to be used with another form of ID at polling stations. That would mean either re-printing new cards to say as much or editing the 28 million cards that have already been printed.

Stinson said he recognized what an important, complex and challenging case he had just heard and said he would report back as soon as possible.