State v. Shabata
In State v. Shabata, 678 P.2d 785 (Utah 1984), the defendant was charged with the murder of his friend.
He requested a lesser included offense instruction for manslaughter, which the trial court refused.
The Court upheld the trial court's refusal, explaining that "all the evidence the defendant presented at trial was to the effect that he had not caused his friend's death and that he had never injured or even argued with him."
The Court concluded that the defendant's "own theory of defense precluded the requested instruction on manslaughter."
In that case, there was simply no rational basis in the evidence presented at trial requiring a lesser included offense instruction.