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Legal Mental Capacity: A Psychiatrist's Perspective


In 1995 the California legislature amended the Probate Code on the subject of legal mentalcapacity. The Due Process in Competency Determinations Act (DPCDA), which is embodied insections 810-814 of the Probate Code, requires that a determination of lack of mentalcapacity be supported by evidence of a deficit in at least one specific mental function.This requirement and other changes in the code provide modern standards for judges andmental health evaluators to determine whether “a person is of unsound mind or lacksthe capacity to make a decision or do a certain act.” This article addresses selectedmental deficits that can affect a person’s competence.

A question of competence may arise in such matters as wills, trusts, contracts, prenuptialagreements, health care decisions, and conservatorship proceedings. DPCDA can help anattorney determine whether a client is impaired and in need of a clinical evaluationregarding impairment. Moreover, a mastery of DPCDA will enable lawyers to collaborateeffectively with treating physicians and mental health experts.

When an attorney has doubt about a client’s competence, a referral to an expert inmental illness is often worthwhile. The expert may help in the following ways: (1)determine whether mental deficits exist, (2) determine whether mental deficitssignificantly affect legal mental capacity, (3) establish a diagnosis, (4) determinewhether a mental disorder is treatable, and (5) determine whether the mental deficits maybe reversible.

DPCDA Guidelines

According to the DPCDA, a mere diagnosis of a physical or mental disorder in and of itselfis not sufficient to establish lack of capacity. Rather, a judicial determination ofincompetence should be based on evidence “of a deficit in one or more of theperson’s mental functions.” Furthermore, the code requires a finding ofsignificant impairment with respect to “the type of act or decision inquestion,” and the court may take into consideration “the frequency, severity,and duration of periods of impairment.”

Section 811 of the Probate Code divides mental functions into four broad domains in whichdeficits may be found. These domains are: (1) alertness and attention, (2) informationprocessing, (3) thought processes, and (4) ability to modulate mood and affect.

Alertness and Attention

The first domain of mental functioning mentioned in the code is “alertness andattention.” Four levels of alertness (or consciousness) have been described: alert,drowsy, stuporous, or comatose. Stupor is defined as inability to remain conscious unlessrepeatedly aroused. If an individual is less than alert, the ability to pay attention andother types of mental functioning will likely be compromised.

Within this first domain, four spheres of orientation are identified. They are: time,place, person, and situation. Of these, orientation to time (e. g., date, year) isgenerally the most sensitive to organic brain dysfunction. Disorientation to person,place, and situation often occur together. Thus, a client who does not understand he orshe is in an attorney’s office (place) may well not grasp being with an attorney(person) or the nature of the work to be done with the attorney (situation).

Information Processing

Memory is a mental function listed in the domain of information processing. An attorneyshould be concerned that a client has a memory deficit in the following instances: (1) areport of forgetfulness by the client, family, or friends, (2) forgetfulness that becomesapparent during the consultation, and (3) over-reliance by the client on others to answerquestions. Impaired memory is a cardinal feature of a dementing disorder such asAlzheimer’s disease.

The Probate Code refers to “short- and long-term memory, including immediaterecall.” Immediate recall refers to an individual’s ability to registerinformation and repeat it back at once. If new information does not register, it will notbe stored for recall.

Short-term memory (STM) refers to a person’s ability to remember relatively newinformation--e. g., data presented ten minutes previously. In the realm of health care forexample, the patient who cannot assimilate new information about a proposed medicaltreatment will be hard-pressed to give an informed consent. In the course of dementia, STMis usually affected before long-term memory (LTM).

LTM refers to the ability to recall old information, such as one’s birth date, namesof relatives, and widely-known historical facts. An example of an LTM deficit interferingwith decision-making is the client who wishes to bequeath assets but does not remembereither the assets or the potential beneficiaries.

Thought Processes

Hallucinations and delusions are deficits that are mentioned in the third domain, thoughtprocesses. A hallucination is defined in the American Psychiatric Press Textbook ofPsychiatry (2nd ed.) as follows: “A perceptual distortion for which there is noexternal stimulus.” Hallucinations may occur in various disorders, includingschizophrenia and dementia, and they may occur in any one of the five senses. Inschizophrenia for example, a person may hear a voice commanding that personal belongingsbe given away to strangers. In such a case, the individual would most likely beincompetent on the basis of the hallucinations.

A delusion is defined as a fixed, false belief that is not amenable to reality testing.There are various kinds of delusions, including grandiose, persecutory, and jealous types.In dementia for example, a jealous delusion may interfere with competence, as in thefollowing scenario: An elderly gentleman with severe Alzheimer’s disease resides in anursing home. He sees his wife of many years speak once to a male nursing attendant. Onthis basis, he develops the totally unfounded and irrational belief that she is having anaffair with the attendant, and he suddenly decides to divorce her.

Ability to Modulate Mood and Affect

According to the American Psychiatric Glossary, mood refers to a “a pervasive andsustained emotion.” A mood disturbance can adversely impact a person’s judgment.For example, someone with a clinical depression may refuse medical treatment due tofeelings of worthlessness, helplessness, and guilt.

The psychiatric term “affect” (with the accent in pronunciation placed on thefirst syllable) refers to how emotion is expressed. Affect may be disturbed in variousways, such as being blunted, inappropriate, or unstable. In dementia for example, theremay be an overall blunting of emotional expression. Indifference in someone with dementiain the face of a life-threatening medical condition is an example of a disturbance ofaffect interfering with competence.

Detecting Mental Deficits

Clinically, it is not always obvious that an individual has a mental deficit. InAlzheimer’s disease for example, someone with mild-to-moderate illness may hideintellectual impairments well, and there may supportive friends or family who respond forthe individual, thus obscuring deficits. In addition, many people with dementia retain anappearance of physical well-being and are quite sociable, thereby belying cognitivedysfunction.

Nevertheless, the presence of mental deficits may be indicated by telltale signs otherthat the features mentioned above. For example, someone with dementia may demonstrate thefollowing: a look of befuddlement, trouble grasping explanations, lack of spontaneity,reduced amount of speech, word-finding difficulty (e. g., calling a chair a“thing”), and vagueness. Someone with schizophrenia may be disheveled, have astrange demeanor, and have bizarre beliefs. And someone with depression may be sociallywithdrawn, speak and move slowly, and have oppressive negative thoughts.


The Due Process in Competency Determinations Act requires that a determination ofincompetence be supported by one or more specific mental deficits. This article hasdescribed selected mental deficits that may cause lack of competence. An attorney who isknowledgeable about mental deficits will best be able to ascertain whether a client lackslegal mental capacity, communicate about competency, and determine when referral to anexpert in mental illness is indicated.