People v. Hendrix, 515 P.3d 22

Early morning, Hendrix approached an Oxnard house, knocked, rang the doorbell, entered the backyard, pushed open a screen door and tried the sliding glass door, then sat on a backyard bench when police arrived.
Hendrix told officers he was looking for his cousin Trevor, who in fact did not live at that address; Hendrix had no burglary tools and only a water bottle.
Hendrix was charged with first-degree residential burglary (specific-intent crime) and convicted after trial.
The trial court instructed the jury on mistake of fact using the general-intent (reasonable-belief) version of CALCRIM No. 3406 rather than the specific-intent version that permits an unreasonable but honestly held belief to negate mens rea.
The Court of Appeal found the instructional error harmless under People v. Watson and affirmed; a dissent urged Chapman review (constitutional standard).
The California Supreme Court reversed the Court of Appeal, holding the instructional error was prejudicial under Watson and remanding for further proceedings (the Court did not decide which standard—Watson or Chapman—governs).

Issue	Plaintiff's Argument	Defendant's Argument	Held
Proper standard for reviewing prejudice from the mistaken-fact instruction error	Apply Watson (state-law harmless-error test)	Error misinstructed mens rea/element; Chapman (constitutional harmless-beyond-a-reasonable-doubt) applies	Court assumed without deciding both standards; found error prejudicial under Watson, so reversal warranted
Was the inclusion of a reasonableness requirement for mistake of fact prejudicial?	Harmless: jurors would reject Hendrix’s story as fabricated; no reasonable probability of a different outcome	Prejudicial: jury was centrally disputed on intent; an honestly held but unreasonable belief could have produced acquittal	Prejudicial under Watson: instruction likely affected jurors’ appraisal of an honestly held (even if unreasonable) mistake; reversal and remand ordered

People v. Watson, 46 Cal.2d 818 (establishes the California state-law harmless-error standard)
Chapman v. California, 386 U.S. 18 (federal harmless-beyond-a-reasonable-doubt standard for constitutional error)
People v. Wilkins, 56 Cal.4th 333 (misinstruction on an element can require Chapman review)
People v. Molano, 7 Cal.5th 620 (discusses mistake-of-fact/unreasonable-belief instruction and treats its omission as subject to Watson review in context)
Neder v. United States, 527 U.S. 1 (misdescribing or omitting an element precludes proper jury finding)
United States v. Gaudin, 515 U.S. 506 (jury must find every element beyond a reasonable doubt)
People v. Thompson, 27 Cal.3d 303 (burglary is a specific intent offense)