## Facts

- David Koperski was charged with first degree sexual assault based on sexual contact with K.O. on a couch at his house after an evening of drinking.
- K.O. and her friend Marti went to Lincoln to drink and dance, briefly stopped at a birthday party for Koperski, and later returned to his house after being unable to enter a friend’s apartment.
- An after-hours gathering was ongoing when they arrived; both K.O. and Koperski had consumed alcohol, but neither was obviously impaired.
- K.O. lay down on a living-room couch under a comforter and fell asleep; Koperski checked on her several times after guests left.
- K.O. testified that Koperski woke her and kissed her; she kissed him back. The later sexual contact formed the basis of the charge.
- The trial centered on whether K.O. consented and whether Koperski reasonably believed she consented.

## Issues

1. Whether the trial court erred by failing to instruct the jury on consent and on the defendant’s reasonable but mistaken belief in consent when there was evidence supporting that theory.
2. Whether omission of such instructions prejudicially impaired the defense by preventing the jury from considering a theory that, if accepted, would require acquittal because the State failed to prove lack of consent beyond a reasonable doubt.

## Decision

- The Nebraska Supreme Court reversed the Court of Appeals’ affirmance of the conviction.
- The court held the trial court should have instructed on Koperski’s theory that he reasonably believed K.O. consented, because there was evidence from which a jury could so find.
- The instructional omission was prejudicial because it concerned the central disputed issue and the State’s burden to prove lack of consent.
- The case was remanded with directions to vacate the judgment and grant a new trial.

## Legal Principles

- A criminal defendant is entitled to a jury instruction on any theory of defense supported by any evidence, even if the supporting evidence comes solely from the defendant’s testimony.
- When lack of consent is an element of sexual assault, evidence permitting a finding that the defendant reasonably believed there was consent can require an instruction reflecting that theory.
- Instructions that state the elements in general terms may be insufficient if they do not fairly submit the defendant’s supported defense theory to the jury.
- Failure to give a supported defense instruction is reversible error when it may affect the verdict and cannot be treated as harmless.

## Conclusion

The court ordered a new trial because some evidence supported a defense theory of consent or reasonable mistaken belief of consent, and the jury was not properly instructed to evaluate that theory in deciding whether the State proved lack of consent beyond a reasonable doubt.


State v. Koperski, 578 N.W.2d 837 (Neb. 1998)