The admitted evidence tampering and forgery by a single Massachusetts lab worker has led to the likely dismissal of more than 20,000 wrongful drug convictions, which is possibly the largest mass-dismissal of criminal convictions in U.S. history.

In fact, according to a New York Times report, an attorney with the ACLU of Massachusetts, Carl Williams, stated, “We’re all overjoyed today at having what is, we think, the largest dismissal of criminal cases as a result of one case in the history of the United States of America.”

This mass-dismissal is the most recent consequence of the case against Annie Dookhan, a former state chemist who pleaded guilty to 27 counts in 2013, including counts related to evidence tampering, perjury and obstruction of justice.

While her coworkers believed she was simply a fast worker, it was eventually discovered that her decision to cut corners was partially the reason for her impressive level of productivity. In fact, she was found to have forged signatures and returned positive drug results on tests she never actually bothered to complete, among other transgressions.

Following her conviction in 2013, she was sentenced to serve three to five years in prison, but was paroled last year.

Just how many drug convictions are being dismissed?

The Associated Press reports that the state’s highest court ordered district attorneys to determine how many of the estimated 24,000 cases involving Dookhan “they would be unable or unwilling to prosecute if the defendants were granted new trials.”

According to the ACLU, as many as 21,587 cases have already been recommended for dismissal, although they will likely not be formally dismissed by court action until Thursday.

In a statement, Matthew Segal, the legal director of the ACLU of Massachusetts, said, “Today is a major victory for justice and fairness, and for thousands of people in the commonwealth who were unfairly convicted of drug offenses.”