After he was rushed unconscious to a hospital, doctors had to revive the "dead" man five times.
On Wednesday, the appeals court upheld the lower court's ruling.
Benjamin Schreiber was sentenced to life in prison without parole in 1997 after being convicted of first-degree murder.
In 2018, Schreiber applied to a state court for release, arguing that he had "momentarily died" at the hospital and therefore fulfilled his life sentence.More news: Stephen Curry Could Miss Entire Remainder Of 19-20 Season
They said that he was "unlikely" to be dead, as he had signed his own legal documents in the case.
When he lost consciousness at the University of Iowa Hospitals & Clinics, a staff member called his brother, who told the hospital that although it could give Mr Schreiber medicine to ease his pain, "otherwise you are to let him pass", according to Mr Schreiber's petition.
In 2015, Schreiber kidney stones caused infectious poisoning.
The dead man walking argued in court papers that he was sentenced to life without parole - "not to life plus one day", the Des Moines Register reported.More news: US needs to follow up with message to killers
At the time of writing, Schreiber remains incarcerated at the Iowa State Penitentiary, and it's not known if he plans to take his unique case to a higher court.
"The court finds this assertion unpersuasive and without merit", it stated. It notes that Schreiber cited no case law to bolster his arguments.
"Benjamin "Edward Schreiber", 66, is both nonetheless alive, wherein case he should stay in jail, or he's lifeless, wherein case this attraction is moot, 'a choose in Iowa dominated on Wednesday".
"We do not believe the legislature intended this provision [.] to set criminal defendants free whenever medical procedures during their incarceration lead to their resuscitation by medical professionals", Potterfield wrote.More news: DNA found in suspect's apartment likely to be Grace Millane's