Elections Canada has made a last-minute motion to file new evidence to the Supreme Court of Canada in Conservative MP Ted Opitz's appeal of an April court decision that overturned the federal election result in Etobicoke Centre.

Elections Canada says it has located some of the voters whose ballots were thrown out because of registration certificates that were missing or were unsigned.

In a motion filed with the Supreme Court a few days ago, Elections Canada says it conducted what it calls "The Probe" shortly after Liberal Borys Wrzesnewskyj won his application to have the 2011 election result declared void in the Toronto riding.

The former three-time MP lost the Etobicoke Centre election by 26 votes, but contested the result in court, claiming irregularities with 181 ballots. The judge threw out 79 of the ballots, enough to void the election result.

Opitz, who won the riding in May, 2011 appealed the decision to the Supreme Court of Canada, which will hear the case in a rare summer sitting next Tuesday. The court has returned from its summer break in order to expedite the case.

Elections Canada has found that 44 of the voters who were disqualified in the court hearing are in fact on the National Register of Electors, a permanent and constantly updated list of all 24 million potential voters in Canada.

Voter registration certificates missing

The heart of the lower court decision was about missing registration certificates, or registration certificates that were not signed by the voter. Ontario Superior Court Justice Thomas Lederer was concerned that there was no way of determining whether the voters were Canadian citizens, in the absence of the certificates.

Registration certificates are filled out by potential voters who arrive at a poll on election day but who are not on the voters list for that poll. The certificates contain their names, addresses and signatures, and constitute the proof that the voter has shown proper ID, and is a Canadian citizen.

Elections Canada has filed a chart with the Supreme Court, showing that 44 of the 52 people whose ballots were discarded due to missing registration certificates are on the National Register of Electors, which means they are Canadian citizens and qualified to vote.

It's possible, therefore, that those 44 people should have been allowed to have their votes counted, which would put a serious dent into Wrzesnewskyj's case to nullify the election.

But there is a problem.

Although the names and addresses of those 44 voters are redacted in the court document, a code shows that almost half of them did not live in Etobicoke Centre in the month before the election.

It is possible that these voters could have moved into the riding during the election period, but since their registration certificates are missing, there's no proof that they were residents of Etobicoke Centre when they voted.

In its motion, Elections Canada says it is a neutral party and takes no position on whether the evidence should be added to the appeal.

But the motion raises a question about why Elections Canada didn't do this research when Wrzesnewskyj first raised the issue of missing registration certificates.

An Elections Canada briefing note obtained by CBC through Access to Information shows that election officials knew as early as last fall, months before the first court hearing in April, that many registration certificates could not be found.

If Opitz loses his appeal on Tuesday, he will no longer be an MP, and a date for a byelection in Etobicoke Centre must be set within six months.