Perhaps CBP will weigh offences differently based on the date of 10/17/18 (pre & post). Cannabis offences after October 17 , 2018 might be looked at in a lessor light, compared to criminal offences when marijuana was still illegal in Canada so that forgiven or expunged these people were still criminals committing crimes Who are trying to enter the US. Only time will tell at this point.
Under the
Expungement of Historically Unjust Convictions Act (Expungement Act), the Parole Board of Canada (PBC) is the official and only federal agency responsible for ordering or refusing to order expungement of a conviction.
This legislation allows for the destruction or permanent removal of judicial records of historically unjust convictions from federal databases.
A process is now in place to expunge historically unjust convictions, which includes eligible offences involving consensual sexual activity with a same-sex partner that would be lawful today.
Certain convictions under the Criminal Code as well as certain convictions under the National Defence Act are eligible for expungement.
Persons convicted of an offence listed in the
schedule to the Expungement Act are eligible to submit an application to the PBC to have the record(s) of their conviction(s) expunged. If the person is deceased, an appropriate representative, such as a close family member or a trustee, can apply on their behalf.
When an expungement is ordered, the person convicted of the offence is deemed never to have been convicted of that offence.
https://www.canada.ca/en/parole-board/services/expungements/expungement.html
I know US Border services have access to Canadian records, Ron but I doubt they store the info which means their searches would turn up empty. At least that's the way I read the law.