I think that any time Parliament decriminalizes activity that was previously criminal in the code—in other words, now it's no longer criminal—people shouldn't suffer the stigma of a criminal record for having engaged in that behaviour in the past. If Parliament today says it's not illegal, I don't understand why you should suffer the effects of it.
Evidence of meeting #159 for Public Safety and National Security in the 42nd Parliament, 1st session. (The original version is on Parliament’s site, as are the minutes.) The winning word was conviction.
A recording is available from Parliament.