Thousands of cannabis convictions in the US have been expunged by the San Francisco District Attorney’s office using technology to deal with a backlog of cases being reviewed after the drug was legalized.

More than 9,300 individuals have had their convictions sealed under the program, meaning they have better access to jobs and housing.

Known as the Adult Use of Marijuana Act (AUMA), or Proposition 64, the law in California was changed last January to broadly legalize the recreational use of cannabis for over-21s.

Shortly after it passed the district attorney for San Francisco, George Gascon, made the decision to retroactively apply it for all misdemeanor and felony convictions dating back to 1975.

The benefits of reclassifying and dismissing these convictions were described as “innumerable” by the DA’s office, noting: “A cleared conviction can reduce barriers to employment, housing, and educational opportunities for millions of people impacted by the American criminal justice system.”

However the practicalities of sealing records of those convicted to make it easier for them to apply for jobs was proving a problem, and often required them to engage in a drawn-out petition process.

SAN FRANCISCO, CA - DECEMBER 09: San Francisco district attorney George Gascon speaks during a new conference to announce a civil consumer protection action against rideshare company Uber on December 9, 2014 in San Francisco, California. Gascon, along with Los Angeles district attorney Jackie Lacey, announced the filing of a civil consumer protection action against Uber Technologies Inc. for making false and misleading statements to consumers and for engaging in business practices that violate C
Image:George Gascon said he was thrilled to see other DA’s following his lead

Now, the DA’s office – working with a charity called Code For America – has applied a new technology which proactively goes through conviction records and automatically processes ones which are fit to be sealed.

“Prosecutors should act to address the inherent unfairness of penalising people for activity that is no longer illegal,” said George Gascon.

“Using technology, we have been able to proactively bring greater racial equity and fairness to marijuana legalisation in California.

“I am thrilled to see other counties and states following suit by offering similar relief in their communities. It’s the right thing to do.”

The US has the largest documented incarceration rate in the world, although the numbers of people in prison and jail in nations such as China is subject to dispute.

A large proportion of those incarcerated in the US belong to ethnic minority groups, which the DA’s office said was the product of “the failed war on drugs”.

In San Francisco, roughly 33% of the dismissed convictions involved African Americans, and 27% involved Latin Americans, disproportionate figures compared to the demographics of the city.

“Contact with the criminal justice system should not be a life sentence, so we’ve been working to reimagine the record clearance process,” said Jennifer Pahlka, founder of Code for America.

“Our work asks how we can make government work better for the people it serves, and we are honored to partner with DA Gascon’s office to deliver relief to thousands who have been blocked from access to jobs, housing and other opportunities for so long.

“This new approach, which is both innovative and common sense, changes the scale and speed of justice and has the potential to ignite change across the country.”