Diminished Capacity


By David Dixon Ph.D.

In most states, there are four established levels of criminal culpability: intent, knowledge, recklessness, and negligence.  A defendant is ultimately found to have diminished capacity when a mental disorder has impaired his/her ability to form the culpable mental state to commit the crime for which he or she is charged.

“Christopher” (name changed for this article) is a 31 year old married male with a four year old son.  He had been employed in customer service for Costco at the time of his evaluation.  He had no prior history of criminal offense.  Christopher planned to return to school and complete a master’s degree in business.  He and his wife had decided to accept her parents’ kind invitation to live in the basement of their home to save money.

The arrangement worked relatively well.  The grandparents cared for their grandson, while Christopher and his wife worked long hours. However, things began to slowly change.  Christopher thought his in-laws had taken some of his clothing.  He confronted them and they denied his accusations.  Later he expressed concerns that they were watching him. Eventually, he set up video cameras to spy on his in-laws.  Shortly thereafter, when the TV began talking to him harshly, he became agitated, throwing it through the home’s front picture glass window.

Fearing for her own and Christopher’s safety, his sister-in-law called 911.  Christopher was charged with domestic violence and assault.  He was transported to a County Jail.  Was he culpable and criminally responsible for the alleged crime he committed?  Was he mentally ill?

It has been estimated by some experts that nearly 70% of jailed inmates suffer from some type of mental illness.  Inmates charged with felony offenses and who are psychotic, delusional, mentally compromised, or have a personality disorder may be candidates for a diminished capacity defense.  In Christopher’s case, his symptoms were consistent and logically associated with an understandable and concrete mental health diagnosis.  Even if “acute” or short-term, it was a severe disorder.

A diagnosis of Acute Psychotic Disorder was established by careful assessment and a convergence of data from a wide range of sources including:  A forensic psychological interview, his current mental status examination, medical/psychiatric records from his primary care doctor and some old college health care records mentioning friends who showed concern.

Collateral reports (including family members, police and witnesses) were gathered.  Christopher was then administered objective psychological tests which supported the provisional diagnosis.

A diminished capacity defense requires effective collaboration with a psychologist who can point out the “weaknesses” of the case.  The expert must also be able to establish good rapport with the defendant to thoroughly gather appropriate, valid information and conduct a reliable interview and examination.  Equally important is the expert’s demeanor and ability to defend a clinical report, while maintaining composure on the stand in a sometimes hostile courtroom environment.

Juries tend to like simple, crystal clear explanations, free of “psychobabble”.  There is an advantage if a defendant can articulate and recall his or her mental state at the time of the alleged crime.  A poor memory of the incident may complicate a successful defense.

Christopher and his attorney decided to take their case to trial, relying on the diminished capacity argument as their primary defense.  The jury was left to ponder whether Christopher acted at the time of the crime with intent and a goal-oriented purpose.

Christopher was found not guilty.