Murray filed papers in court that claim that Jackson could be found partially responsible for his own death. Attorney Michael Flanagan wants a judge to test again the residual substance contained in a bottle of propofol found in Jackson's room.
They say those results could prove whether the singer self-injected a fatal dose of propofol. If he did, the restitution order could be reduced.
Prosecutors want Murray to pay Jackson's children more than $100 million in restitution based on the projected earnings of the "This Is It" tour, along with funeral and memorial service expenses.
A hearing on the matter is set for next week.
A jury found Murray guilty on Nov. 7 of involuntary manslaughter in the pop singer's death.
