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Florida’s ‘Secret’ Formulas to Calculate Release Dates May Be Trapping People in Prison

The ACLU’s ongoing battle to force the Florida Department of Corrections to release the formulas it uses to calculate release dates for imprisoned people.

Tomoka Correctional Institution in Daytona Beach, Florida.
Photo by Paul Hennessy/Getty Images

Florida’s ‘Secret’ Formulas to Calculate Release Dates May Be Trapping People in Prison

The ACLU’s ongoing battle to force the Florida Department of Corrections to release the formulas it uses to calculate release dates for imprisoned people.


When a person is sentenced to a period of time in prison, determining their date of release seems like it would be a simple calculation. Many states, however, use formulas and communication processes that lead to frequent errors and result in holding thousands of people in prison long after their sentences have ended.

In Florida, the Department of Corrections calculates release dates by using a computer program called the Offender Based Information System (OBIS) or by hand. According to attorneys for the state’s  Department of Corrections, when employees calculate a person’s release date manually, no written guidelines are provided. Moreover, the formulas programmed into OBIS remains hidden from public scrutiny.

In 2019, the American Civil Liberties Union of Florida filed a lawsuit in Leon County to obtain detailed information about how the DOC calculates release dates for the roughly 80,000 people held in state prisons. But rather than make those formulas public, America’s third-largest state prison system has been fighting to ensure it remains secret.

“How the FDOC figures out release dates affects tens of thousands of people in prison and their families as well as its own internal planning,” Benjamin Stevenson, an attorney for the state ACLU working on the case, told The Appeal in a written statement. “It is important FDOC gets it right.  Yet, FDOC evades public accountability and oversight when it refuses to share its ‘secret’ calculation.  Without public access to the formula FDOC uses, we cannot applaud it for its good work or help it correct its calculations.”

In responses to questions from the ACLU of Florida, the state says it cannot release its computer algorithms without compromising the physical security of DOC buildings, a claim the state ACLU believes is ludicrous. Spokespeople for the FDOC said the agency does not comment on pending litigation.

Overdetention has quietly become a problem endemic to America’s network of state-level prison systems. In recent years, several states have revealed that, because of either sloppy training or computer glitches, thousands of people have been imprisoned beyond their judge-issued sentences.

The problems have led to lawsuits and controversies in multiple jurisdictions, including California, Massachusetts, Hawaii, Washington, D.C., and Alaska. Early this year, in Arizona, KJZZ reporter Jimmy Jenkins exposed that a software bug was keeping hundreds of people imprisoned beyond their sentences. In a particularly egregious case, Louisiana officials knew for years that hundreds, and possibly thousands, of imprisoned people were being held past their sentence completion dates, and took no action. One man was held for 960 days—nearly three years—more than his sentence.

The ACLU of Florida says it wants to ensure that the same issues are not occurring in Florida. The DOC responded by releasing some information in January 2020—but not the actual formulas. The agency said the ACLU hadn’t asked for the formulas specifically, but when the ACLU filed a follow-up records request, the DOC refused to provide the formulas. In May 2020, the ACLU sued a second time.

In March, Leon County Circuit Judge John C. Cooper ordered the DOC to release more records to the ACLU, but the civil rights group maintains that it still does not fully understand how release dates are calculated. The two parties are set to meet in another discovery hearing June 7. In the future, the ACLU hopes to use this information to propose bills that could decrease incarceration rates across Florida. In particular, the group wants to amend the state’s “truth-in-sentencing” law that mandates that people must serve at least 85 percent of their prison sentences.

“Most of these individuals will eventually be released and will return to our communities,” ACLU of Florida attorney Jackie Azis told The Appeal. “For those individuals and their loved ones, the accuracy of FDOC’s calculated release date is critically important. FDOC’s refusal to share how it calculates release dates is Kafkaesque. Decisions that impact people’s lives are being made and we have no idea how.”

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