Decision-making Capacity and Legal Competence

Decision-making capacity and legal competence are terms often used interchangeably in a hospital setting to describe an individual’s ability to make consequential decisions regarding themselves, as a manifestation of their autonomy. More specifically, however, capacity describes a patient’s ability to make autonomous decisions regarding their care, as determined by a physician, whereas competence is a legal term that describes a person’s ability to participate in legal processes, as determined by a judge.

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Decision-making Capacity


Decision-making capacity is a patient’s ability to understand a proposed intervention, its benefits, risks, and alternatives, including the option of no treatment, and make autonomous decisions regarding their care. 

  • Decision-making capacity:
    • The manifestation of a person’s ability to exercise their autonomy
    • A task-specific functional assessment of an individual by a physician
    • Dependent on adequate disclosure of information
    • Not static: can change within an individual based on the presence or absence of reversible factors (e.g., medication side effects)
  • Decision-making capacity is expressed as:
    • The ability to provide informed consent
    • Informed refusal of treatment
  • Underlying principle: “respect for persons,” or the acknowledgment of a patient’s “personhood”
  • The precise definition may vary between states and countries.

Components of medical decision-making capacity

There are 4 primary components of medical capacity:

  1. Understanding
  2. Communication/expression of choice
  3. Appreciation
  4. Reasoning
Table: Determinant elements of medical decision-making capacity
Component Determinant elements
  • Demonstrable understanding of the benefits, risks, and alternatives to an intervention
  • Includes the possibility of rejecting treatment altogether
Communication/expression of choice
  • Ability to communicate a choice clearly and consistently
  • Must be rooted in reality
  • Understanding that their decisions will have consequences
  • Ability to apply the information to one’s self and situation
  • Appreciation of the potential benefits and consequences of being exposed to risks
  • Capable of making a risk/benefit calculation: risks and benefits of action versus inaction
  • Logically and rationally manipulate and compare information
  • Normal thought processes
  • Able to articulate their reasoning
  • Ability to align available treatment options with their life experience, circumstances (e.g., socioeconomic status), and guiding principles and philosophies (e.g., religion)
Components of medical capacity

Components of medical decision-making capacity

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Assessment of Capacity

The clinician assesses the 4 elements intuitively through everyday interactions with the patient (e.g., during daily rounds).

Steps for systematic evaluation

The steps below usually take the form of a fluid conversation that doesn’t necessarily follow a strict order. Throughout the conversation, the clinician should be able to determine if the patient fulfills the 4 elements. 

  1. Provide a summary of the patient’s condition. Ask for feedback to gauge the understanding of the patient. Use questions such as, “What is your understanding of your condition?”
  2. Provide a summary of the available treatment options with their risks and benefits along with the outcomes if no treatment is performed. Ask the patient for feedback using questions such as:
    • What are the treatment options available? 
    • What are the benefits and risks of each option? 
    • What do you understand will happen if nothing is done?
  3. Provide a recommendation regarding treatment or how best to proceed. Ask for feedback using questions such as:
    • Do you believe this course is right for you? 
    • Is there any aspect of the course that scares or troubles you?

Assessment tools

  • Capacity evaluation tools:
    • Aid to Capacity Evaluation (ACE)
    • Hopkins Competency Assessment Test (HCAT)
    • Understanding Treatment Disclosure
    • MacArthur Competence Assessment Tool for Treatment
    • Assessment of Capacity for Everyday Decisions (ACED)
  • Cognitive evaluation tools:
    • Mini-Mental State Examination
    • Montreal Cognitive Assessment

Impaired capacity

  • Impaired capacity is the lack of decision-making capacity.
  • Any illness or treatment that compromises cognition may be associated with reduced capacity.
  • The clinician may suspect impaired capacity with the following:
    • Inability to express a decision
    • Immediate acceptance/refusal of care
    • Absence of questions about the course of action
    • Excessive/inconsistent reasons for refusing care
    • Newly developed dependency
    • Hyperactivity, disruptive behavior, or agitation
    • Labile emotions or affect
    • Hallucinations
    • Intoxication 
  • Diagnoses (e.g., Alzheimer’s disease) are not substitutions for capacity evaluations.
Table: Risk factors for impaired decision-making capacity
Fear or discomfort Expression of fear or discomfort in a clinical setting
  • Minors (< 18 years of age): Some countries allow for “partial consent” from the age of 14 years.
  • Elderly (> 85 years of age)
Neurologic, psychiatric, or developmental conditions
  • Impaired cognition, use of language, and orientation to person, time, and space, especially in individuals with:
    • Dementia (e.g., Alzheimer’s disease)
    • Psychosis (e.g., schizophrenia)
  • Inability to have a logical conversation, sound argument, etc.
  • Developmental delay/intellectual disability preventing a patient from understanding the intervention in the simplest of layperson’s terms
Significant cultural or language barriers Inability to understand the clinical team due to lack of language competency

Determination of capacity

  • The final decision lies with the treating physician.
  • All assessments of capacity (e.g., conversations and results using evaluation tools) must be documented in the clinical record. 
  • If capacity remains uncertain after evaluation with these tools, the next steps include:
    • Assessment by a specialized clinician (e.g., psychiatrist)
    • In complex or controversial cases, the medical team can seek judicial review to determine competency.
    • When in doubt, the determination should typically err on the side of the patient having capacity.

Results determining that a patient has impaired capacity

  • Restriction of the patient’s autonomy (prevention of unintended or irreparable harm)
  • Patients will require surrogate decision makers:
    • Legal power of attorney awarded by the patient
    • Closest relative (determined by local laws, typically next of kin)
    • Court-appointed health guardians may also be considered in certain jurisdictions.
  • If a patient without capacity continues to refuse treatment, court proceedings may be required to give treatment despite objection (in non-urgent cases only).

Legal Competence


Competency, or competence, is a legal term defined as the ability of an individual to participate in legal proceedings, which includes their ability to make medical decisions. Determinations of competence are made by a judge and not by a physician.

  • The determination of competence is a legally binding determination that establishes whether or not a patient is allowed to make their own medical decisions.
  • Competence refers to many areas of a person’s life, including their competency to:
    • Make medical decisions
    • Stand trial
    • Be a parent
    • Make a will
    • Sign a contract
  • Legal competence is a quality that is presumed in every individual.
  • Demonstrating a lack of competence requires the presentation of evidence before a judge, who makes the final determination. (Forensic psychiatrists and/or other clinicians may be called upon for testimony.)
  • Competence is often used interchangeably with “capacity,” but capacity should only refer to the expression of autonomy that can be determined by a physician on a case-by-case basis. 

Components of competence

The components of competence as determined by a judge are listed below. Note the similarity to the 4 components of medical decision-making capacity. 

  • Ability to understand and process relevant information 
  • Ability to communicate a choice
  • Ability to reason and deliberate
  • Ability to hold appropriate values and goals
  • Appreciation of one’s circumstances and the possible consequences


  1. Karlawish, J. (2020). Assessment of decision-making capacity in adults. In Wilterdink, J.L., and Solomon, D. (Eds.), UpToDate. Retrieved June 9, 2021, from
  2. Barstow, C., Shahan, B., Roberts, M. (2018). Evaluating medical decision-making capacity in practice. American Family Physician, 98(1), 40–46.
  3. Brendel, R.W., Wei, M.H., Schouten, R., Edersheim, J.G. (2010). An approach to selected legal issues: Confidentiality, mandatory reporting, abuse and neglect, informed consent, capacity decisions, boundary issues, and malpractice claims. The Medical Clinics of North America, 94(6), 1229–1240. 
  4. Have, H., Gordijn, B. (2013). Handbook of global bioethics. Dordrecht: SpringerReference. 
  5. Palmer, B.W., Harmell, A.L. (2016). Assessment of healthcare decision-making capacity. Archives of Clinical Neuropsychology: The Official Journal of the National Academy of Neuropsychologists, 31(6), 530–540.
  6. Libby, C., Wojahn, A., Nicolini, J.R., Gillette, G. (2021). Competency and capacity. StatPearls. Treasure Island (FL): StatPearls Publishing. Retrieved from
  7. Buchanan, A. (2004). Mental capacity, legal competence and consent to treatment. Journal of the Royal Society of Medicine, 97(9), 415–420. 

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