## Facts

- Miss B. testified that Franklin Mayberry accosted her near a store, threatened her, struck her, forced her to accompany him, and took her to an apartment where he sexually assaulted her; she did not resist further out of fear.
- Miss B. testified that Booker T. Mayberry entered the apartment afterward, assaulted her, and attempted to rape her; she resisted Booker, and Franklin’s intervention allowed her to escape.
- Police and other witnesses observed bruising consistent with an assault.
- Franklin testified Miss B. accompanied him willingly and consented to intercourse; he claimed the conflict arose only after Booker appeared.
- Booker denied assaulting Miss B.
- Franklin requested a jury instruction requiring acquittal if he honestly and reasonably believed Miss B. freely consented; the trial court refused.

## Issues

1. Whether, in a prosecution for forcible rape and related kidnapping, the jury must be instructed that an honest and reasonable belief in the complainant’s voluntary consent is a defense when supported by evidence.
2. Whether failure to give that mistake-of-fact instruction was prejudicial as to Franklin’s rape and kidnapping convictions.

## Decision

- The California Supreme Court held the trial court erred by refusing to give a mistake-of-fact instruction on Franklin’s honest and reasonable belief in consent.
- The error was prejudicial and required reversal of Franklin’s rape and kidnapping convictions.
- The court affirmed Franklin’s remaining convictions (including oral copulation and simple assault).
- The court affirmed Booker’s conviction for assault with intent to commit rape.

## Legal Principles

- A reasonable and good-faith mistake of fact may negate the intent required for crimes that depend on the defendant’s perception of the victim’s lack of consent.
- In prosecutions for forcible rape (and related kidnapping), when substantial evidence supports that the defendant honestly and reasonably believed the complainant voluntarily consented, the defendant is entitled, upon request, to an instruction explaining that such belief is a defense.
- General instructions on actual consent are insufficient if they do not explain how a reasonable mistake about consent bears on the required mental state.
- Failure to instruct on a supported defense theory is reversible when it creates a reasonable probability of a different outcome on the affected counts.

## Conclusion

The court recognized that an honest and reasonable belief in voluntary consent can defeat the mental element of forcible rape and related kidnapping, and it reversed Franklin Mayberry’s rape and kidnapping convictions because the jury was not instructed on that defense, while affirming the remaining convictions.


People v. Mayberry, 15 Cal. 3d 143, 542 P.2d 1337 (Cal. 1975)