The German man jailed for killing and eating a person he met over the internet is to face a retrial.
Meiwes' defence team say he should serve only five years
A federal court ordered Armin Meiwes to stand trial again after prosecutors appealed against his eight-and-a-half year manslaughter sentence.
The prosecution argues that Meiwes, who was jailed in January 2004, should have been given a life sentence for murder.
His lawyers however want his original sentence reduced on the grounds that his victim had volunteered to be eaten.
Meiwes, a 43-year-old computer technician, killed and ate Bernd Juergen Brandes after posting an advert on the internet in 2001 asking for a willing victim.
Object of fancy
The case has fascinated Germany and has been the subject of a song and a film script, and a documentary is in the works.
During the original trial in Kassel, prosecutors described how Meiwes had "slaughtered his victim like a piece of livestock and treated him as an object of his fancy".
A psychiatrist who gave evidence at the trial said Meiwes was incapable of showing "warm and tender feelings towards others".
Meiwes told the court his motive for killing and eating his victim came from a desire for a younger brother he never had - "someone to be part of me".
Trial judge Volker Muetze said the crime had been "an act between two extremely disturbed people who both wanted something from each other".
"Seen legally, this is manslaughter, killing a person without being a murderer," he added.
The federal court has now overturned the verdict and the retrial is expected to be held in Frankfurt.