Earlier quoted context omitted.
I can't find mention of him making that specific promise of pardoning all non-violent drug crimes. I did find https://joebiden.com/justice/ saying: > Biden believes no one should be in jail because of cannabis use. As president, he will decriminalize cannabis use and automatically expunge prior convictions. And, he will support the legalization of cannabis for medical purposes, leave decisions regarding legalization…
He's talking about changing laws, which of course he can't literally do, but Presidents always claim to do and they do have a lot of influence over Congress.
NC passed a Second Chance Act which makes it easier to expunge records, says https://abc11.com/second-chance-act-roy-cooper-signed-into-l... , and "Cases dismissed after December 1, 2021 may automatically be expunged per the Second Chance Act." says https://www.swlawnc.com/blog/new-expungement-law-in-nc which adds that laws in other states have automatic removal of dismissed charges after a period of time.
This means that my quote from Wikipedia about expungement isn't the full story.