Madam Speaker, in regard to completing one's sentence, the main point of that is administrative. There are administrative challenges to removing a record in the midst of a proceeding, and this has never been done before. The barrier this could create is mostly theoretical because, as we know, the penalties for the actual offences have been short. It is very unlikely that there is anyone right now sitting in a jail cell for simple possession of cannabis, so the practical downside is likely insignificant.
In the House of Commons on May 6th, 2019. See this statement in context.