TORONTO -- Fraud and reduced public confidence in the electoral system could result if voter information cards are used as valid ID at the polls, lawyers for the federal government argued in court Friday.

The government is fighting an injunction request to suspend a key identification provision in its Fair Elections Act.

The Council of Canadians and the Canadian Federation of Students are asking the court to restore the power of Canada's chief electoral officer to recognize voter information cards as one form of valid ID -- a power taken away in the act -- in time for the fall election.

Government lawyer Christine Mohr said in court there is "a long history of concern" over the use of voter information cards. The Harper government made changes to voter identification laws last year. Questions over security, reliability and incidents of misuse and fraud prompted the changes, she said.

"The use of voter information cards could lead to inconsistent application of the (voting) laws," Mohr told the judge.

She warned that ineligible voters could cast a ballot using the cards as one form of ID and the public's confidence in the electoral system as a whole would be diminished.

The council and federation argued in court Thursday that disallowing voter information cards as valid ID could disenfranchise tens of thousands of voters, but the government disagrees with that figure.

"Our concern is that there is not a rational, empirical basis for this number and it's not well supported," Mohr said.

In 2011, 400,000 voters used the voter information card as valid ID as part of a pilot project, but Mohr says it's unknown how many of those actually needed the card because they had no other option. If some of those who used the card had another option, then those voters will be able to cast a ballot in the next election, casting doubt on the estimate of tens of thousands, she said.

The government said the use of voter information cards as valid ID is not needed to ensure Canadians have the ability to vote. The cards may make it easier for some people to vote, but convenience is not the government's duty, Mohr said.

Voters have the option to chose from dozens of different forms of identification, and those pieces of identification are easy to obtain, she said.

"There is no constitutional requirement for this particular document," Mohr said.

She said that the 45 accepted forms of identification include many government-issued documents, such as a statement of benefits for employment insurance, the Canada Pension Plan or a tax assessment.

Before the Fair Elections Act was introduced the chief electoral officer announced his intention for the upcoming election to allow Canadians to use the voter identification cards as valid ID -- along with one supporting document that wouldn't have to contain an address. A factum prepared by Elections Canada and submitted to the court said if the injunction is granted Marc Maynard will authorize the use of voter information cards across Canada.