Also known as:diminished capacity · diminished capacity defense
Written by attorneys · grounded in primary & secondary sources — see below
3 senses
1
in criminal law
Evidence of mental abnormality that a criminal defendant may introduce to negate a required mental element of the charged offense.
2
Sense 1
1
in criminal law
Evidence of mental abnormality that a criminal defendant may introduce to negate a required mental element of the charged offense.
Sources & Authorities· 2 sources
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Casebooks
Cases
Sense 2
2
in criminal law
Evidence of mental abnormality that a criminal defendant may introduce to reduce the degree of the offense for which the defendant may be convicted.
Sources & Authorities· 2 sources
Select any source to read its text and confirm it supports the definition.
Casebooks
Cases
Sense 3
3
in professional responsibility
A rule permitting a lawyer who reasonably believes that a client has diminished capacity, faces substantial physical financial or other harm unless action is taken, and cannot adequately act in the client's own interest to take reasonably necessary protective measures including consulting third parties or seeking appointment of a guardian.
Sources & Authorities· 2 primary sources
Select any source to read its text and confirm it supports the definition.
Evidence of mental abnormality that a criminal defendant may introduce to reduce the degree of the offense for which the defendant may be convicted.
3
in professional responsibility
A rule permitting a lawyer who reasonably believes that a client has diminished capacity, faces substantial physical financial or other harm unless action is taken, and cannot adequately act in the client's own interest to take reasonably necessary protective measures including consulting third parties or seeking appointment of a guardian.
Each sense below has its own examples, sources, and questions.
Examples2
Expert Testimony on Mental State
Damian Decker was charged with murder after shooting a police officer. He offered psychiatric evidence that his schizophrenia prevented him from forming the intent to kill. The trial court excluded the testimony on the ground that it did not meet the state's insanity standard. The Supreme Court upheld the exclusion because the evidence was offered only to rebut the mens rea element rather than to establish a complete defense.
Clark v. Arizona548 U.S. 735, 752 n.20, 126 S.Ct. 2709, 165 L.Ed.2d 842 (2006)
Intellectual Disability and Sentencing
Diana Delgado was charged with murder. She offered psychiatric evidence that her intellectual disability prevented formation of the required mental state. The trial court excluded the testimony on the ground that it did not meet the state's insanity standard. The appellate court affirmed because the evidence was offered only to rebut the mens rea element rather than to establish a complete defense.
Hall v. Florida572 U.S. 701 (2014)
Frequently Asked2
What are the two main variants of the diminished capacity doctrine in criminal law?+
One variant permits evidence of mental abnormality to negate a required mental element of the charged offense. The second variant permits the same evidence to reduce the degree of the offense even when all formal elements of the higher offense are satisfied.
Supporting sources
How does diminished capacity evidence function at capital sentencing?+
Evidence that a mental disease or defect substantially impaired the defendant's capacity to appreciate the wrongfulness of the conduct or to conform conduct to law is admissible as mitigation. The evidence may support a sentence of imprisonment rather than death even if it does not establish legal insanity.
Supporting sources
Examples1
PTSD Evidence at Trial
Dustin Donovan was convicted of murder. He sought to introduce expert testimony that his PTSD prevented formation of the required mental state. The trial court excluded the testimony. The appellate court affirmed because the evidence did not negate any element of the offense and Texas does not recognize a partial-responsibility variant of diminished capacity.
Williams v. State502 S.W.3d 262 (Tex. Ct. App. 2016)
Examples1
Lawyer Considers Protective Steps
Deborah Dunn met with her lawyer to sign a personal guarantee on a new store lease. She disclosed her bipolar disorder and that she had stopped her medication weeks earlier. She spoke rapidly, projected sales triple those of her current business, and refused to discuss risks while demanding immediate execution. The lawyer reasonably believed Deborah could not protect her own interests and faced substantial financial harm, so the lawyer consulted family members about possible guardianship.
Frequently Asked2
When may a lawyer take protective action for a client with diminished capacity?+
A lawyer may take protective action when the lawyer reasonably believes the client has diminished capacity, faces substantial harm unless action is taken, and cannot adequately act in the client's own interest. Protective steps may include consulting family members or seeking appointment of a guardian.
Supporting sources
Does information about a client with diminished capacity remain confidential?+
Yes. Information remains protected by Rule 1.6. When taking protective action the lawyer is impliedly authorized to reveal information only to the extent reasonably necessary to protect the client's interests.
Supporting sources
548 U.S. 735, 126 S. Ct. 2709, 165 L. Ed. 2d 842 (2006)Criminal Law
…given different meanings, see, e.g., Morse, Undiminished Confusion in Diminished Capacity, 75 J. Crim. L. & C. 1 (1984) (“The diminished capacity doctrine allows a criminal defendant to introduce evidence of mental abnormality at trial either to negate a mental element of the crime charged, thereby exonerating the defendant of that charge, or…