California voters approved marijuana legalization exactly a month ago today. But even before a single vote was counted, law-enforcement officials in San Diego County were proactively preparing to let former marijuana “offenders” out of jail.

Long one of the country’s most marijuana-friendly states, all California adults aged 21 and up can now legally possess up to an ounce of marijuana and grow up to six plants in their homes following the landslide approval of Prop. 64 on Nov. 8.

While retail marijuana shops won’t be in business until 2018, the new possession limits went into effect at 12:01 a.m. on Nov. 9—which was when anyone in custody for a former “crime” could petition for release.

And criminal justice officials were ready.

Well before the vote, San Diego-based KPBS reports, prosecutors and court officials sifted through court records with defense attorneys to identify anyone “in custody, so we could accomplish [their release] that much faster,” said Rachel Solov with the San Diego District Attorney’s Office.

About 20 people in San Diego County have already been released from custody, the station reported. “Dozens more” are expected to have sentences reduced for earlier-than-expected releases, and as many as 300 more will get off of probation early, KPBS reported.

Similar homecomings are happening across the state. Prosecutors in Sacramento, San Mateo, and San Francisco counties counted a total of about 375 other cases where sentences would be reduced or inmates released outright.

But Prop. 64’s impact will reverberate far beyond jails. Many more people could finally find relief from decades-old convictions for petty marijuana offenses. San Diego public defenders say they still receive calls from clients whose old marijuana offenses are preventing them from obtaining jobs.

And, in case you’ve forgotten, most of the people whose lives were wrecked by marijuana prohibition are black or Latino.

About 2,000 people in county jails or state prisons in California were eligible to have their sentences reduced under Prop. 64, the Drug Policy Alliance told the San Francisco Chronicle last month.

State bean-counters say that legalization will save the state tens of millions of dollars in incarceration and enforcement costs—and, ironically, it’s been the counties with the hardest-line policies on cannabis (which also opposed legalization) who have been the biggest beneficiaries.

Prior to the vote, hardline anti-pot folks said that Prop. 64 wasn’t legalization at all—and would in fact lead to more cannabis users in prison.

Since cultivation of even a single marijuana plant was a potential felony prior to the vote and is now legal, and penalties for sales, production, and transportation have all been significantly reduced, it’s unclear where that logic began—but its flaws are obvious.

Legalization also paves the way for ex-offenders to enter the marijuana industry. The state’s licensing scheme allows for required state permits to be denied to certain felons, but allows for exceptions for anyone convicted of a marijuana crime—the same former “crimes” that could soon be expunged.