It's a thought that no one really wants to confront, even for those who are in favor of prison reform and changing the way we go about the "War on Drugs": that it's possible for prison employees and officials to make mistake that actually force inmates to stay in prison longer than they should.
Such a sentiment was made clear recently after the U.S. Justice Department released some incredible statistics detailing 152 federal inmates that were kept in prison longer than they should have been. The statistics are from 2009 to 2014. While most of the inmates only spent a month or less longer in a jail cell than they should have, that's still an unacceptable and outrageous amount of time to have to spend behind bars without reason. Worse yet, there was one inmate that spent one year longer behind bars than he should have.
Out of a pool of 462,000 inmates, that's a pretty low error rate. But again: this shouldn't be happening at all! The error rate should literally be zero. These are people's lives we're talking about, and when they have served their time for whatever offense they were convicted of, then they deserve to go free. Not a month late. Not a week late. And not even a day late.
The report also outlined roughly 4,000 inmates who were released in an "untimely" fashion but that these inmates were not held longer as a result of a staff error (unlike the previously mentioned 152 inmates).
Source: Reuters, "'Staff errors' led to 152 U.S. inmates serving extra time: report," Julia Harte, May 24, 2016