The defence case was to have ended Monday but Justice Guy Cournoyer told the 14-member jury that lawyers were not in a position to continue.
Magnotta is charged with first-degree murder and four other charges in the slaying and dismemberment of Chinese engineering student Jun Lin.
Magnotta admits to the physical acts surrounding Lin's death but has said he was suffering from a mental disorder at the time of the slaying in May 2012.
Two psychiatrists have testified that Magnotta was in a psychotic state and was incapable of telling right from wrong.
The Crown is arguing the crimes were planned and deliberate.
Magnotta is also charged with criminally harassing Prime Minister Stephen Harper and other members of Parliament; mailing obscene and indecent material; committing an indignity to a body; and publishing obscene materials.