Del Mastro and Richard McCarthy, the Conservatives' official agent for the Peterborough riding campaign, were found guilty in November of exceeding the federally mandated spending limit and of submitting a false or misleading document to Elections Canada. Del Mastro, who at one time served as parliamentary secretary to the prime minister, was also found guilty of donating too much to his own campaign.
Del Mastro and McCarthy were also found guilty of submitting a campaign return that didn't properly provide the information required.
As the official agent for the campaign, McCarthy handled the money and signed off on expenses.
Each conviction carries a maximum penalty of $2,000, one year in prison, or both, according to a release from the Crown prosecutor's office.
A spokesman for Crown prosecutor Tom Lemon wouldn't reveal what penalty Lemon plans to seek.
Weeks after Del Mastro and McCarthy were convicted, a judge in Guelph, Ont., sentenced Michael Sona to nine months in jail for planning and conducting illegal robocalls to deter people from voting in the 2011 federal election. It is thought to be the first incarceration for an offence under the Canada Elections Act.
Could move to reopen case
Sona is appealing his sentence, arguing it is unnecessarily harsh given he is a first-time offender who has already suffered considerably. The Crown is also appealing the sentence, arguing it fails to reflect the gravity of the offence.
Del Mastro had said last fall that he would seek to reopen his defence, but his lawyer, Leo Adler, wouldn't comment to CBC News on what to expect in court today. A court official told CBC News there was no motion on file for the case.
Del Mastro, in an interview with Rosemary Barton on CBC News Network's Power & Politics on Oct. 31, the day he was found guilty, said there was a debate until the last few days of the trial on whether his lawyers should bring a motion to present additional evidence.
In the end, they did not.
"We were confident that the ruling was going our way. We felt that we had put forward a very strong case, we thought that we had not just Elections Canada precedent but actual statements and evidence provided by the chief auditor at Elections Canada that entirely supported our case, but ultimately we didn't hear that considered in the ruling," he said.
Just the judge's opinion, Del Mastro says
Del Mastro also characterized the guilty finding as a matter of opinion.
Judge Lisa Cameron's ruling "was not a final decision," he said. "I've in no way broken any of the laws governing elections."
"I know what the truth is. That's her opinion. My opinion is quite different."
Del Mastro resigned his seat in the House of Commons a few days after the conviction, just before MPs were to vote on whether to suspend him.
He has served as an MP from Jan. 23, 2006, until Nov. 5, 2014.
The Conservative Party has not yet chosen a candidate to run in the Peterborough riding for this year's federal election.