The state of Maryland has freed 13 prisoners convicted of murder, following an appellate court ruling that said jurors were given improper instructions in the decades-old cases.

The 2012 ruling by the state Court of Appeals, Maryland’s highest court, could eventually result in about 200 inmates receiving new trials or being set free, including those convicted of homicide, attempted murder and rape.

Prior to 1980 judges usually told jurors to take into account not just the facts of a case, but what the law meant, effectively eliminating the need to consider the concept of reasonable doubt.

Baltimore state’s attorney’s office released 14 inmates it says do not pose a threat to public safety—13 murderers and one man convicted of attempted murder. The men all served more than 30 years in prison and are mostly elderly and in poor health.

In fact, one of the men who was released, 72-year-old Yusuf Rasheed (aka Joseoh Westry), died of a heart attack the day after he left prison, having spent more than 37 years behind bars for killing his estranged wife and her lover. Another prisoner was released, but transferred to federal custody.

“It’s absolutely the right decision,” Mike Millemann, a professor at the University of Maryland School of Law, who is working with dozens of inmates fighting for release under the Court of Appeals ruling, told the Baltimore Sun. “These guys had fundamentally unfair trials. Really dysfunctional, structurally defective trials.”

-Noel Brinkerhoff, David Wallechinsky

To Learn More:

Thirteen Murderers Released after Court Ruling (by Ian Duncan and Yvonne Wenger, Baltimore Sun)

Criminal Cases Affected by the Maryland Court Ruling (Baltimore Sun)

Over A Dozen Convicted Murderers Released From Prison On Technicality (WJZ-CBS Baltimore)