The federal government is going to court to defend one of the most controversial changes to the criminal pardons system made by the previous Conservative government.

In 2010, Parliament changed the Criminal Records Act to extend the waiting period required to apply for a pardon, to 10 years from five for indictable offenses.

And, in a move that drew a great deal of criticism, the amendment was made retroactive to anyone who had already been sentenced under the old law and was awaiting a pardon. The changes came into force in March 2012.

One man who was caught up in the retroactive application of the law is challenging its constitutionality in an Ottawa court next week.

Michael Charron had served four months after pleading guilty to trafficking cocaine in 2008. He had served his time and had completed his probation when the government changed the law.

"He pleaded guilty knowing that he would be able, if he led a pro-social lifestyle, to apply for a pardon. Before he could commence his application, Parliament changed the waiting period to 10 years," wrote Charron's lawyer, Michael Spratt, in a document filed this week at court.

He added that Charron has been drug-free and law-abiding since getting out of prison.

'Lesser punishment'

Spratt argues that extending the waiting period is unconstitutional because it violates the section of the charter that says offenders are entitled to the "lesser punishment" if Parliament changes the rules mid-process.

He cites evidence from University of Toronto criminology professor emeritus Tony Doob, who agrees that extending the waiting period is punitive because having a criminal record makes it harder to find an apartment and get a job.

"Although it is impossible to predict human behaviour perfectly, it appears that the pardon legislation that Canada has had for more than 40 years is quite successful; approximately 96 per cent of pardons that have been granted have not been revoked," Doob stated.

According to the document, Justice Canada lawyers — in an unusual move — cross-examined Doob although they did not challenge his findings.

Goodale, federal lawyers disagree

In his submission to the court, Spratt also highlighted a story first reported by CBC News in January 2016, in which Public Safety Minister Ralph Goodale said some changes by the Conservatives were "punitive" and would be reviewed.

"Protecting the public is important, but we also need to look at the issue of balance and fairness and proportionality, and we will examine all of those things in reference to this issue," Goodale said at the time.

Yet in the document it filed in the Charron case, the government argues that a criminal record is nothing more than "an administrative result of the conviction," and is not punitive in any way.

"If a criminal record significantly impacted an offender's liberty or security interests one would expect pardons or record suspensions to be in high demand among past offenders. However, the statistics show that only 11 per cent of people with criminal records choose to apply for them," wrote Alain Prefontaine, senior Justice Canada lawyer.

Prefontaine adds that while the Supreme Court of Canada has recognized that state-imposed measures can sometimes result in stigma, the charter does not protect against speculative infringements on rights

Curiously, Justice Canada also argues with the oft-cited fact that almost all of those granted pardons have remained on the right side of the law. It suggests the current record suspension system is deficient.

"The problem with the 96 per cent statistic is that it can only be relied upon if the pardons system was functioning properly, including reviewing pardons and revoking them where necessary. While the applicants rely on this statistic as an indication that the system was functioning well, it can equally be seen as an indication that the system was not performing its function of making sure that pardoned offenders stayed on the right track," wrote Prefontaine.

In an email to CBC News Tuesday, Goodale's office said the government is committed to reforming the legislation related to pardons.

"That commitment is not diminished by the arguments on the constitutionality of the Criminal Records Act," spokesman Scott Bardsley said.

"Our government is also committed to bringing in reforms responsibly through statutory change," he added. "Until statutory reforms are made, the government will continue to defend the law as written."

Both sides will expand on their arguments when the case goes before an Ontario superior court judge next week in Ottawa.