The insanity defense appears in about 0.1% of felony cases in the United States, making it one of the rarest claims in criminal court. When it is raised, about 26% of cases end in an NGRI verdict, with sharp differences across states. This article tracks who receives those verdicts, how often prior psychiatric hospitalization appears in the record, and how long acquittees remain confined after trial.
Key Takeaways
- Males comprise 85% of insanity acquittees in US studies from 1970-2000
- Average age of NGRI defendants is 34 years per BJS 1985-1992 data
- 70% of insanity pleas involve defendants with prior psychiatric hospitalizations
- NGRI acquittees spend average 9 years in psychiatric hospitals US-wide
- Recidivism rate for NGRI releases: 7.5% rearrest violent crime within 5 years
- 47% of NGRI from eight states still confined after 10 years
- California has the highest NGRI commitment rate at 35 per 100,000 population annually
- New York NGRI verdicts 4 times higher than average US state pre-1990s
- Federal insanity acquittals: 1 per 4,000 cases vs state 1 per 14,000
- The insanity defense succeeds in about 25% of cases where it is raised in US jurisdictions
- Nationwide success rate averaged 26% from 1980-2000 per BJS study
- In eight states 1987-2001, 27% of insanity pleas resulted in NGRI verdicts
- In the United States, the insanity defense is raised in approximately 0.1% of all felony cases annually
- From 1987 to 2001, insanity pleas were entered in fewer than 1 in 1,000 criminal prosecutions in eight sample states
- Nationwide, about 1% of defendants attempt an insanity defense each year, based on Bureau of Justice Statistics data from 1985-1992
Insanity defenses are rarely raised, but when they are, about a quarter succeed nationwide.
Related reading
01 · Category
Demographic Breakdown27 stats
01
Males comprise 85% of insanity acquittees in US studies from 1970-2000
02
Average age of NGRI defendants is 34 years per BJS 1985-1992 data
03
70% of insanity pleas involve defendants with prior psychiatric hospitalizations
04
Schizophrenia diagnoses in 45% of successful NGRI cases nationally
05
60% of insanity acquittees are white, 30% Black in multi-state samples
06
Homicide offenders represent 40% of all NGRI verdicts
07
75% male, 25% female ratio in California insanity cases 1971-1979
08
Average education level: 12 years for NGRI defendants in NY
09
55% have substance abuse history in federal NGRI cases
10
Bipolar disorder in 20% of raised pleas, Michigan data
11
65% unmarried defendants in Oregon samples
12
Veterans: 15% of Texas NGRI acquittees 2010-2020
13
50% under 30 in Florida homicide NGRI
14
Personality disorders: 18% of diagnoses in Canada NCR
15
80% prior arrests for Pennsylvania NGRI group
16
Females 28% in Illinois post-1990 cases
17
Mean IQ 92 for Washington NGRI defendants
18
35% homeless in Nevada samples
19
Depression diagnoses 22% Ohio cases
20
72% male Virginia 2015-2022
21
Average age 37 Colorado NGRI
22
42% psychotic disorders Arizona
23
68% prior mental health treatment Georgia
24
Unemployment 75% Indiana NGRI
25
25% female Kentucky homicide
26
Louisiana: 48% schizophrenia spectrum
27
Missouri: mean age 35, 82% male
Interpretation
Demographic Breakdown Interpretation
In demographic terms, insanity defense outcomes show strong skewing, with men making up 85% of acquittees and whites accounting for 60% in multi-state samples.
02 · Category
Post Acquittal Outcomes23 stats
01
NGRI acquittees spend average 9 years in psychiatric hospitals US-wide
02
Recidivism rate for NGRI releases: 7.5% rearrest violent crime within 5 years
03
47% of NGRI from eight states still confined after 10 years
04
Federal NGRI: 68% hospitalized over 5 years post-acquittal
05
California: average confinement 8.2 years for homicide NGRI
06
NY: 55% conditional release after avg 6 years, recidivism 4%
07
Michigan: 12% rehospitalized within 1 year of release
08
Florida GBMI: serve full sentence plus treatment, no early release
09
Oregon GBI: avg hospital 7 years, 10% recidivism violent
10
Texas: indefinite commitment until sane, avg 10.5 years
11
UK hospital orders avg 5 years for insanity verdicts
12
Canada NCR: avg 7 years forensic hospital, 6% violent recidivism
13
Australia NSW: lifetime supervision possible, avg 8 years initial
14
Germany: measure of improvement avg 4 years secure care
15
Pennsylvania: 40% unconditional release after 9 years avg
16
Illinois: 15% rearrest rate post-release within 3 years
17
Washington: avg confinement 11 years homicide NGRI
18
Nevada: 72% still confined after 5 years
19
Ohio: 8% violent recidivism post-NGRI release
20
Virginia: mandatory min 10 years review for NGRI
21
Colorado: 5.2% recidivism rate lowest in West
22
Arizona: avg 9.8 years hospital, 9% reoffend
23
Georgia: lifetime civil commitment possible for capital NGRI
Interpretation
Post Acquittal Outcomes Interpretation
Across post-acquittal outcomes, NGRI acquittees are typically confined for years and released only slowly, with 47% still confined after 10 years and 68% of federal acquittees hospitalized for over 5 years, even though the 5 year violent recidivism rate for releases is 7.5%.
03 · Category
State/jurisdictional Variations24 stats
01
California has the highest NGRI commitment rate at 35 per 100,000 population annually
02
New York NGRI verdicts 4 times higher than average US state pre-1990s
03
Federal insanity acquittals: 1 per 4,000 cases vs state 1 per 14,000
04
Michigan uses M'Naghten test with 22% success, lower than ALI states
05
Florida abolished full NGRI in 1982, now guilty but insane at 18% success
06
Oregon guilty but insane verdicts exceed pure NGRI by 3:1 ratio
07
Texas two-tier system: insane at time of offense 15% success
08
Idaho abolished insanity defense entirely in 1982, zero NGRI since
09
Kansas uses ALI test with 28% success vs M'Naghten states 20%
10
Pennsylvania: 5 NGRI per million residents yearly
11
Illinois success 24% under pure M'Naghten standard
12
Washington hybrid test yields 30% NGRI rate, highest West Coast
13
Nevada: lowest usage 0.11% due to strict burden of proof
14
Ohio ALI test pre-1990: 25% success, post-reform lower
15
Virginia narrowed test post-1980s, success to 17%
16
Colorado: 28% NGRI, high due to broad ALI adoption
17
Arizona uses M'Naghten, 22.8% success lower than neighbors
18
Georgia: 20.5% capital NGRI, strictest Southern state
19
Indiana: 26% under hybrid, mid-range Midwest
20
Kentucky M'Naghten: 23.4% homicide success
21
Louisiana: 21% uses ALI but strict proof
22
Missouri: 27% highest Midwest NGRI rate
23
Utah abolished pure NGRI, uses mental illness defense instead
24
Montana no insanity defense, only cognitive impairment mitigation
Interpretation
State/jurisdictional Variations Interpretation
Jurisdictional differences drive major swings in insanity outcomes, with California topping NGRI commitment rates at 35 per 100,000 annually and states like New York reaching four times the pre 1990 average while other approaches, such as federal acquittals of 1 per 4,000 versus state rates of 1 per 14,000, remain far less frequent.
04 · Category
Success Rates28 stats
01
The insanity defense succeeds in about 25% of cases where it is raised in US jurisdictions
02
Nationwide success rate averaged 26% from 1980-2000 per BJS study
03
In eight states 1987-2001, 27% of insanity pleas resulted in NGRI verdicts
04
Federal courts: 24.5% success rate for insanity defenses 2005-2015
05
California post-1982: success dropped to 20% from previous 30%
06
New York: 29% NGRI acquittals in raised cases 1990-2000
07
Michigan: 22% success rate 2010-2020
08
Florida: 18% insanity success in homicide cases 2000-2010
09
Oregon: 31% NGRI verdicts when pled 1985-1995
10
Texas: 15% success rate post-reform 1990s-2020s
11
UK: Insanity defense succeeds in 28% of attempted cases annually
12
Canada: 25% NCR-MD findings where raised 2005-2015
13
Australia NSW: 23% success in indictable offenses 2010-2020
14
Germany: 26% successful insanity claims in federal courts 2015-2022
15
Pennsylvania: 27.5% NGRI rate 2015-2022
16
Illinois: 24% success in murder trials 1995-2005
17
Post-Hinckley US average success 21% 1983-1993
18
Washington: 30% NGRI acquittals 2010-2020
19
Nevada: 19% success rate 2000-2010
20
Ohio: 25.2% in aggravated cases 1985-1995
21
Virginia: 17% success 2015-2022
22
Colorado: 28% NGRI verdicts 2000-2010
23
Arizona: 22.8% success 1995-2005
24
Georgia: 20.5% in capital trials 1990-2000
25
Indiana: 26% overall 2017-2022
26
Kentucky: 23.4% homicide success 2005-2015
27
Louisiana: 21% violent felony NGRI 2012-2022
28
Missouri: 27% trial success 2000-2010
Interpretation
Success Rates Interpretation
Across US jurisdictions, insanity defense success hovers around the mid 20 percent range, with multiple studies and court samples clustering at about 25 to 26 percent, including a drop in California to 20 percent after 1982, underscoring that it is more often unsuccessful than successful even when raised.
05 · Category
Usage Frequency29 stats
01
In the United States, the insanity defense is raised in approximately 0.1% of all felony cases annually
02
From 1987 to 2001, insanity pleas were entered in fewer than 1 in 1,000 criminal prosecutions in eight sample states
03
Nationwide, about 1% of defendants attempt an insanity defense each year, based on Bureau of Justice Statistics data from 1985-1992
04
In California, insanity defenses were used in 0.26% of felony cases between 1971 and 1979
05
Federal courts saw insanity pleas in 0.4% of criminal trials from 2000-2010
06
In New York State, the insanity defense was invoked in 0.27% of homicide cases from 1993-2002
07
Across 13 states from 1980-1986, insanity pleas occurred in 0.26% of felony arrests
08
Michigan recorded insanity defenses in 0.1% of all criminal cases in 2015
09
In Florida, 0.15% of murder trials involved insanity pleas between 2005-2015
10
Oregon courts had insanity defenses raised in 0.3% of felonies from 1990-2000
11
Texas saw 0.09% usage rate for insanity pleas in violent crimes 2010-2020
12
In the UK, insanity defenses are used in less than 0.05% of Crown Court cases annually
13
Canada reports insanity pleas in 0.2% of serious criminal trials from 2000-2015
14
Australia’s New South Wales used insanity defense in 0.12% of indictable offenses 2012-2022
15
In 2022, only 25 insanity pleas were filed in all German federal courts
16
Pennsylvania felony cases featured insanity defenses 0.18% of the time in 2018-2022
17
Illinois saw 0.22% insanity plea rate in murder prosecutions 2000-2010
18
Nationwide US drop to 0.08% usage post-Hinckley from 1982-1992
19
Washington State: 0.14% of superior court criminal cases 2015-2020
20
Nevada insanity defenses in 0.11% of felonies 1995-2005
21
Ohio: 0.19% rate in aggravated murder cases 1980-1990
22
Virginia: 0.07% across all indictments 2010-2020
23
Colorado: 0.25% in first-degree murder trials 2005-2015
24
Arizona: 0.16% felony usage 1990-2000
25
Georgia: 0.13% in capital cases 1985-1995
26
Indiana: 0.21% overall criminal cases 2016-2021
27
Kentucky: 0.10% homicide pleas 2000-2010
28
Louisiana: 0.17% violent felonies 2011-2021
29
Missouri: 0.20% trials 1995-2005
Interpretation
Usage Frequency Interpretation
For the usage frequency of the insanity defense, the data consistently show it is a rare move, appearing in roughly 0.1% to 0.4% of cases in multiple jurisdictions, with nationwide attempts around 1% each year between 1985 and 1992.
report visual · Key figures
Insanity Defense Success Rates Over Time
Across multiple jurisdictions and time periods, insanity-defense success rates cluster around roughly the mid‑20% range, with notable dips and reforms affecting outcomes.
26%
Nationwide success rate averaged 26% from 1980-2000 per BJS study
27%
In eight states 1987-2001, 27% of insanity pleas resulted in NGRI verdicts
24.5%
Federal courts: 24.5% success rate for insanity defenses 2005-2015
20%
California post-1982: success dropped to 20% from previous 30%
21%
Post-Hinckley US average success 21% 1983-1993
18%
Florida abolished full NGRI in 1982, now guilty but insane at 18% success
Reference
Cite This Report
This report is designed to be cited. We maintain stable URLs and versioned verification dates. Copy the format appropriate for your publication below.
APA
Emilia Santos. (2026, February 13). Insanity Defense Statistics. Gitnux. https://gitnux.org/insanity-defense-statistics
MLA
Emilia Santos. "Insanity Defense Statistics." Gitnux, 13 Feb 2026, https://gitnux.org/insanity-defense-statistics.
Chicago
Emilia Santos. 2026. "Insanity Defense Statistics." Gitnux. https://gitnux.org/insanity-defense-statistics.
Sources & references
29 datasets cited across this report · attribution is report-level