CALCRIM No. 3455. Mental Incapacity as a Defense (Pen. Code, §§ 25, 29.8)
Judicial Council of California Criminal Jury Instructions (2020 edition)Download PDF
3455.Mental Incapacity as a Defense (Pen. Code, §§ 25, 29.8)
You may not find the defendant guilty of <insert description
of crime> if (he/she) was legally incapable of committing a crime because
of mental incapacity.
The defendant was legally incapable of committing a crime because of
mental incapacity if at the time the crime was committed:
1. (He/She) had a mental disease or defect;
2. Because of that disease or defect, (he/she) was incapable of
knowing or understanding the nature and quality of (his/her) act
or was incapable of knowing or understanding that (his/her) act
was morally or legally wrong.
The defendant has the burden of proving this defense by a
preponderance of the evidence. [This is a different burden of proof from
proof beyond a reasonable doubt.] To meet the burden of proof by a
preponderance of the evidence, the defendant must prove that it is more
likely than not that (he/she) was legally incapable of committing a crime
because of mental incapacity.
New January 2006; Revised April 2008, August 2014
The court has a sua sponte duty to instruct on mental incapacity when the
defendant has raised this defense and substantial evidence supports it. (Pen. Code,
§ 25.) Substantial evidence means evidence of a defense, which, if believed, would
be sufficient for a reasonable jury to find a reasonable doubt as to the defendant’s
guilt. (People v. Salas (2006) 37 Cal.4th 967, 982-983 [38 Cal.Rptr.3d 624, 127
If the court grants a bifurcated trial on the defense of mental incapacity, the court
must also give the appropriate post-trial instructions such as CALCRIM No. 3550,
Pre-Deliberation Instructions, CALCRIM No. 222, Evidence, and CALCRIM No.
226, Witnesses. (See In re Ramon M. (1978) 22 Cal.3d 419, 427, fn. 10 [149
Cal.Rptr. 387, 584 P.2d 524].)
If the court does not grant a bifurcated trial, give the bracketed sentence “This is a
different burden of proof from proof beyond a reasonable doubt.”
• Instructional Requirements. Pen. Code, §§ 25, 29.8, 26.
• Burden of Proof. In re Ramon M. (1978) 22 Cal.3d 419, 427, fn. 10 [149
Cal.Rptr. 387, 584 P.2d 524].).
• Same Test for Both Mental Incapacity and Insanity. In re Ramon M. (1978) 22
Cal.3d 419, 427 [149 Cal.Rptr. 387, 584 P.2d 524].).
• Requirement of Mental Disease or Defect. People v. McCaslin (1986) 178
Cal.App.3d 1, 8 [223 Cal.Rptr. 587].
• Incapacity Based on Mental Disease or Defect. People v. Stress (1988) 205
Cal.App.3d 1259, 1271 [252 Cal.Rptr. 913].
• Penal Code Section 25(b) Supersedes Model Penal Code Test. People v.
Phillips (2000) 83 Cal.App.4th 170, 173 [99 Cal.Rptr.2d 448].
In In re Ramon M. (1978) 22 Cal.3d 419, 427 [149 Cal.Rptr. 387, 584 P.2d 524],
the Supreme Court held that the same test should apply for determining both mental
incapacity and insanity. However, the court was applying the Model Penal Code test,
which was subsequently superseded by Proposition 8 as codified in Penal Code
section 25(b). The Court of Appeal in People v. Phillips (2000) 83 Cal.App.4th 170,
173 [99 Cal.Rptr.2d 448], expressly found that “the test for insanity as stated in
section 25, subdivision (b) applies also to determine whether a person is an idiot
pursuant to section 26.” Accordingly, the committee followed Phillips in drafting
Legal and Moral Wrong
The wrong contemplated by the two-part insanity test refers to both the legal wrong
and the moral wrong. If the defendant appreciates that his or her act is criminal but
does not think it is morally wrong, he or she may still be criminally insane. (See
People v. Skinner (1985) 39 Cal.3d 765, 777-784 [217 Cal.Rptr. 685, 704 P.2d 752];
see also People v. Stress (1988) 205 Cal.App.3d 1259, 1271-1274 [252 Cal.Rptr.
Penal Code Sections 1016, 1017, 1026, 1027
The Supreme Court found in In re Ramon M. (1978) 22 Cal.3d 419, 427 [149
Cal.Rptr. 387, 584 P.2d 524] that the same test for legal incapacity should apply to
both insanity and mental retardation. Moreover, the court concluded that the
Legislature “probably intended [Pen. Code, §§ 1016, 1017, 1026, 1027] to apply to
all persons who assertedly lack mental capacity to commit crime [citation]. In light
of this legislative intent, and of the identity of the legal test for mental incapacity
and insanity . . . we conclude that the term ‘insanity’ in Penal Code sections 1016
through 1027 refers to mental incapacity, whether arising from mental illness or
mental retardation. Accordingly a defendant asserting a defense of mental incapacity
should raise that defense by separate plea (see Pen. Code, §§ 1016, 1017), may
DEFENSES AND INSANITY CALCRIM No. 3455
obtain a bifurcated trial (see Pen. Code, § 1026), [and] must prove his incapacity by
a preponderance of the evidence [citation] . . . .” (Id. at p. 427, fn. 10.)
Extension of Commitment
The test for extending a person’s commitment is not the same as the test for
insanity. (People v. Superior Court (Williams) (1991) 233 Cal.App.3d 477, 490 [284
Cal.Rptr. 601].) The test for insanity and mental incapacity is whether the accused
“was incapable of knowing or understanding the nature and quality of his or her act
or of distinguishing right from wrong at the time of the commission of the offense.”
(Pen. Code, § 25(b); People v. Skinner (1985) 39 Cal.3d 765 [217 Cal.Rptr. 685,
704 P.2d 752].) In contrast, the standard for recommitment under Penal Code section
1026.5(b) is whether a defendant, “by reason of a mental disease, defect, or disorder
[,] represents a substantial danger of physical harm to others.” (People v. Superior
Court, supra, 233 Cal.App.3d at pp. 489-490; People v. Wilder (1995) 33
Cal.App.4th 90, 99 [39 Cal.Rptr.2d 247].)
1 Witkin & Epstein, California Criminal Law (4th ed. 2012) Defenses, § 25.
3 Millman, Sevilla & Tarlow, California Criminal Defense Practice, Ch. 73,
Defenses and Justifications, §§ 73.01, 73.18 (Matthew Bender).
CALCRIM No. 3455 DEFENSES AND INSANITY