Wash. Rev. Code » Title 9A · Chapter 9A.12
Revised Code of Washington

Wash. Rev. Code § 9A.12.010 (2026)

Insanity

✓ current as of May 2026
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To establish the defense of insanity, it must be shown that:
(1) At the time of the commission of the offense, as a result of mental disease or defect, the mind of the actor was affected to such an extent that:
(a) He or she was unable to perceive the nature and quality of the act with which he or she is charged; or
(b) He or she was unable to tell right from wrong with reference to the particular act charged.
(2) The defense of insanity must be established by a preponderance of the evidence.
[ 2011 c 336 s 353; 1975 1st ex.s. c 260 s 9A.12.010.]
Notes of Decisions
Cited in 51 cases (5 in the last 5 years), 1977–2026 · leading case: State v. Crenshaw, 659 P.2d 488 (Wash. 1983).
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State v. Crenshaw, 659 P.2d 488 (Wash. 1983). · cites it 16× “Crenshaw also has a history of mental problems, for which he has been hospitalized in the past. The jury, however, rejected petitioner's insanity defense, and found him guilty of murder in the first degree.”
State v. Rice, 757 P.2d 889 (Wash. 1988). · cites it 5× “" See also RCW 9A.12.010 (codification of M'Naghten test).”
State v. Chanthabouly, 262 P.3d 144 (Wash. Ct. App. 2011). · cites it 7× “See former RCW 9A.12.010 (1975). [7] Both agreed that Chanthabouly suffered from paranoid schizophrenia, [8] a mental disease.”
Clark v. Arizona, 548 U.S. 735 (2006). · cites it 2× “14 Fourteen juris dictions, inspired by the Model Penal Code,15 have in place an amalgam of the volitional incapacity test and some variant of the moral incapacity test, satisfaction of either (generally by showing a defendant’s substantial lack of capacity) being enough to…”
State v. Crenshaw, 617 P.2d 1041 (Wash. Ct. App. 1980). · cites it 6× “RCW 9A.12.010. [10] Defendant next contends that we should apply the American Law Institute (ALI) insanity test, rather than the M'Naghten insanity test.”
State v. Atsbeha, 142 Wash. 2d 904 (Wash. 2001). · cites it 2× “This evidence would be relevant and admissible to establish an insanity defense under RCW 9A.12.010, 48 but not relevant and admissible to establish a diminished capacity defense.”
State v. Atsbeha, 16 P.3d 626 (Wash. 2001). · cites it 2× “This evidence would be relevant and admissible to establish an insanity defense under RCW 9A.12.010, [48] but not relevant and admissible to establish a diminished capacity defense.”
State v. McDonald, 571 P.2d 930 (Wash. 1977). · cites it 4× “Commonwealth, 76 Pa. 414, 425 (1874). [11] We do not think this requirement of proof in any way emasculates the requirement that the prosecution prove every element of the crime beyond a reasonable doubt.”
State v. Chanthabouly, 164 Wash. App. 104 (Wash. Ct. App. 2011). · cites it 4× “See former RCW 9A.12.010 (1975). 7 Both agreed that Chanthabouly suffered from paranoid schizophrenia, 8 a mental disease.”
State v. Brett, 892 P.2d 29 (Wash. 1995). · cites it 2× “The prosecutor never *198 expressly mentioned insanity or RCW 9A.12.010(1)(b), which provides that "as a result of mental disease or defect, the mind of the actor was affected to such an extent that .”
State v. Klein, 124 P.3d 644 (Wash. 2005). · cites it 3× “RCW 9A.12.010. Conversely, the absence of such a condition is the threshold inquiry when an insanity acquittee petitions for full release from state commitment.”
State v. Box, 745 P.2d 23 (Wash. 1987). · cites it 4× “RCW 9A.12.010 provides in part: To establish the defense of insanity, it must be shown that: (1) At the time of the commission of the offense, as a result of mental disease or defect, the mind of the actor was affected to such an extent that: (a) He was unable to perceive the…”
Show all 51 citing cases →
— Wash. Rev. Code § 9A.12.010(1) — 13 cases
State v. Rice, 757 P.2d 889 (Wash. 1988). “" See also RCW 9A.12.010 (codification of M'Naghten test).”
Allstate Ins. v. Raynor, 143 Wash. 2d 469 (Wash. 2001).
Allstate Ins. Co. v. Raynor, 21 P.3d 707 (Wash. 2001).
State v. Chanthabouly, 164 Wash. App. 104 (Wash. Ct. App. 2011). “See former RCW 9A.12.010 (1975). 7 Both agreed that Chanthabouly suffered from paranoid schizophrenia, 8 a mental disease.”
State v. Chanthabouly, 262 P.3d 144 (Wash. Ct. App. 2011). “See former RCW 9A.12.010 (1975). [7] Both agreed that Chanthabouly suffered from paranoid schizophrenia, [8] a mental disease.”
— Wash. Rev. Code § 9A.12.010(1)(a) — 2 cases
In Re Est. of Kissinger, 206 P.3d 665 (Wash. 2009).
State v. Crenshaw, 617 P.2d 1041 (Wash. Ct. App. 1980). “RCW 9A.12.010. [10] Defendant next contends that we should apply the American Law Institute (ALI) insanity test, rather than the M'Naghten insanity test.”
— Wash. Rev. Code § 9A.12.010(1)(b) — 5 cases
State v. Crenshaw, 659 P.2d 488 (Wash. 1983). “Crenshaw also has a history of mental problems, for which he has been hospitalized in the past. The jury, however, rejected petitioner's insanity defense, and found him guilty of murder in the first degree.”
State v. Brett, 892 P.2d 29 (Wash. 1995). “The prosecutor never *198 expressly mentioned insanity or RCW 9A.12.010(1)(b), which provides that "as a result of mental disease or defect, the mind of the actor was affected to such an extent that .”
State v. Chanthabouly, 164 Wash. App. 104 (Wash. Ct. App. 2011). “See former RCW 9A.12.010 (1975). 7 Both agreed that Chanthabouly suffered from paranoid schizophrenia, 8 a mental disease.”
State v. Chanthabouly, 262 P.3d 144 (Wash. Ct. App. 2011). “See former RCW 9A.12.010 (1975). [7] Both agreed that Chanthabouly suffered from paranoid schizophrenia, [8] a mental disease.”
State v. Cameron, 674 P.2d 650 (Wash. 1983).
— Wash. Rev. Code § 9A.12.010(2) — 6 cases
State v. Rice, 757 P.2d 889 (Wash. 1988). “" See also RCW 9A.12.010 (codification of M'Naghten test).”
State v. Chanthabouly, 262 P.3d 144 (Wash. Ct. App. 2011). “See former RCW 9A.12.010 (1975). [7] Both agreed that Chanthabouly suffered from paranoid schizophrenia, [8] a mental disease.”
State v. Greene, 960 P.2d 980 (Wash. Ct. App. 1998).
State v. Wheaton, 850 P.2d 507 (Wash. 1993).
State v. Linares, 880 P.2d 550 (Wash. Ct. App. 1994).
— Wash. Rev. Code § 9A.12.010(l)(a) — 2 cases
State v. Linares, 880 P.2d 550 (Wash. Ct. App. 1994).
State v. Jamison, 619 P.2d 352 (Wash. 1980).
— Wash. Rev. Code § 9A.12.010(l)(b) — 4 cases
State v. Crenshaw, 659 P.2d 488 (Wash. 1983). “Crenshaw also has a history of mental problems, for which he has been hospitalized in the past. The jury, however, rejected petitioner's insanity defense, and found him guilty of murder in the first degree.”
State v. Brett, 892 P.2d 29 (Wash. 1995). “The prosecutor never *198 expressly mentioned insanity or RCW 9A.12.010(1)(b), which provides that "as a result of mental disease or defect, the mind of the actor was affected to such an extent that .”
State v. Cameron, 674 P.2d 650 (Wash. 1983).
State v. Linares, 880 P.2d 550 (Wash. Ct. App. 1994).
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