Appellant failed to update his sex offender registration within five working days of his birthday because he was depressed, which affected his concentration and memory. The trial court excluded evidence of appellant’s depression, including testimony of an expert witness who would show how depression affects memory. The California Supreme Court granted review to resolve the question of whether forgetting to update one’s registration because of severe depression may negate the section 290 willfulness requirement. The prosecutor argued that willful failure to update one’s registration as a sex offender is a general intent crime, and therefore evidence relating to depression was inadmissible under section 28, subdivision (a). Appellant argued that the due process right to present a defense trumps section 28 in this case. The Court decided that it need not address section 28 or its constitutionality to resolve the case. The willfulness element of section 290 may be negated by evidence that an involuntary condition deprived the defendant of actual knowledge of his or her duty to register. Only the most disabling conditions would qualify, such as Alzheimer’s disease or amnesia. Appellant’s claimed depression did not satisfy this standard. Appellant knew of his duty to register and could have managed to discharge it. Further, the trial court did not abuse its discretion when it refused to let the proffered evidence of depression go to the jury. J. Werdegar dissented in part, holding that the trial court abused its discretion in refusing to consider appellant’s proffered evidence of depression because of its mistaken belief that evidence of mental impairment was legally irrelevant to the question of a defendant’s knowledge of the duty to register.