Articles and Case Studies

Assessment of Capacity

05 Oct 2015

Julian Walter clover

by Dr Julian Walter


We all make countless decisions each day, most of which have marginal impact on our lives. Butter or margarine? Walk or take the lift? Yet the issue of capacity underlies all these decisions, and a person’s capacity is relevant to every situation that requires a decision. 

This article focuses on the assessment of a person’s decision-making capacity in relation to health care.

What is capacity?

Capacity is the ability to make and understand information relevant to a decision, and the ability to appreciate the reasonably foreseeable consequences of a decision (or lack of a decision).1

Generally a person with capacity will be able to:

  • understand the facts of the situation
  • understand the main choices available
  • weigh up those choices, including benefits and risks
  • make and communicate the decision2
  • understand the ramifications of the decision.

It is the ability to go through the process itself that is important, not the decision that is made. We may disagree with the final decision, but this does not equate to a lack of capacity.

Presumption of capacity

The law helpfully tells us there is an automatic presumption that an adult has capacity to make decisions, but that this presumption can be rebutted where the need (and evidence) arises. The reverse presumption applies to a child, i.e. they are presumed not to have capacity, but this position may be rebutted.3

A conclusion that a patient lacks capacity should be supported by facts which should establish why it is more likely (than not) that the patient lacks capacity.

Capacity is elastic and decision specific

The capacity to weigh up a complex decision as to what medical treatment to adopt will usually be greater than the capacity required for simple tasks, such as ordering lunch. Capacity can vary over time, so your findings regarding a patient's capacity and their relevance today may not be the same as tomorrow. Consider the separate issues that may be interfering with your assessment, e.g. language, cultural, knowledge and hearing issues.

There are also different areas of capacity that may not be affected equally – such as testamentary capacity for making a will, criminal capacity enabling a person to stand trial, and financial capacity.4 Specific testing may be required. In terms of medical care, patient autonomy and their right to self-determination is predicated on the ability to weigh up options and ascertain risk.

A patient’s capacity may vary where there is fluctuating impairment to their mental processes, whether through fatigue, effects of drugs or other substances, mental illness or other physiological conditions. Where a patient is deemed to lack capacity, consider how the patient's capacity might be improved, e.g. discussing issues early in the day to assist with fatigue or before certain medications are administered, or delaying decision-making until intercurrent illnesses are managed.

Red flag event

Knowing when to assess capacity can be challenging. Certain “red flag” events are worth considering as a possible indication of capacity impairment and a need for further assessment.5

Examples of red flags include:

  • hasty high-risk decisions
  • decisions that place a person at unexpected risk of harm
  • decisions out of character for the person
  • cognitive decline and abrupt change in mental state
  • serious mental health illness, particularly psychosis.

A conclusion to hand over decision-making power – e.g. Advance Care Directive, Power of Attorney or Enduring Guardian – may also require assessment before the relevant documents are completed.

Some procedures cannot be consented to by a substitute decision maker except by way of court or tribunal. These will vary by jurisdiction, but may include live donation of organs, permanent rendering of infertility and neuro-psychosurgery.

Refusal to be assessed

In most situations, a sensitive explanation of the possible consequences of refusal – e.g. that the patient’s decisions may later be challenged or invalidated – will be enough to resolve the issue. A second opinion may be helpful.

In the event of continued refusal, there are very few circumstances where a patient can be forced to undergo capacity assessment6 and a legal dilemma may arise if detention is required.7 A refusal may also be relevant to the objective findings a clinician relied on to make a decision about the patient’s capacity. Collateral history may be relevant, as are indirect observations regarding demeanour and medical history.

Ensure that the patient is free from undue influence. The patient’s decisions must be made freely and voluntarily and not pressured by others. An interpreter, rather than a family member, will be an important consideration if language issues are present.

Assessment of capacity to make health decisions

The patient needs to understand the nature and effect of the proposed treatment at the point of consent. Although each situation will vary, some general principles apply. Allow for the possibility that this assessment will take some time. Assessment of cognition is different to an assessment of capacity. So just performing a limited cognitive screen, such as a mini-mental state examination or orientation to time/place/person, is generally not sufficient evidence of capacity. Impaired cognition is a “red flag”.

Inform the patient that you are assessing their ability to make a healthcare decision (or a specific decision) and what this will involve. Remember you are not assessing whether you agree or disagree with the patient's decision. You are assessing the patient's ability to weigh up the relevant information and make their decision. There is a risk of patients coming to harm if their decision making is impaired.

The patient should understand their own circumstances, why treatment options are being considered and the range of options available. They should understand what the options involve (including doing nothing) and the impact, benefits and risks. The patient must be able to indicate they want a particular option and articulate why they have chosen this over the other options.

Assessment of capacity to make decisions in other areas

Great care needs to be taken if you are asked to assess a patient's decision-making capacity in areas other than health, e.g. to make a will; or to sign a power of attorney or enduring guardian document.

  • There may be specific issues or legal tests to consider (which should be provided by the person requiring the assessment).8,9
  • You may need to assess and record whether the patient understands specific issues in relation to that legal test.
  • If you don't understand what the patient is contemplating on doing, you may not be able to determine whether the patient is able to consider the relevant issues.
  • You need the ability to objectively assess the validity of the patient's understanding. For example, in assessing testamentary capacity, an objective assessment of the patient's understanding cannot occur without knowing the actual assets held by a patient or their potential benefactors.

Document your findings

This will include your conclusion, reasons and supporting facts, and ideally some record of what the assessment process included. This will help support your reasoning if your decision is later challenged, regardless of your conclusion as to the presence or absence of capacity.

What if you are unsure?

Sometimes the decision as to a patient’s capacity will be uncertain. Can you form a reasonable belief (more likely than not) based on objective reasons? Because there is a (rebuttable) presumption that a patient has capacity, marginal cases may require a conclusion in favour of capacity. You should consider a second opinion.10 Collateral history may be relevant, if privacy or confidentiality concerns can be addressed.

Remember you can usually decline to perform an elective assessment. Where additional information is required before you can begin an assessment, communicate this by contacting the person requesting the assessment, particularly in non-health decision-making.

Although less common in Australia, consider the use of a capacity assessment tool. Various commercial11 and free12,13 options are available, but you should take care that the tool used is appropriate to the task at hand.

What if your assessment demonstrates a lack of capacity?

A substitute decision maker will be required.14 Each state and territory has specific laws regarding the type and hierarchy of decision makers and what must be considered. You may need to obtain advice from our Medico-legal Advisory Service, or bodies such as the Guardianship services available in each state and territory.

Try to determine if the patient has already left some form of guidance, e.g. Advance Care Directive or other decision-making document. Treatment can generally be provided in emergency circumstances and to relieve pain and suffering, although a record should be made of why the treatment was provided without consent and the efforts made to contact a substitute decision maker. Decisions may also need to be made under a general duty of care.15

Capacity assessment in relation to healthcare choices

This assessment will typically occur after the patient has been provided with relevant information, whether by you or another health practitioner in the past. There is no “magical formula” to determine capacity, but the following examples may assist in starting the appropriate discussions.

Can the patient:

  • understand the facts of the situation:

    • “Tell me about what is going on”
    • “Is someone else helping you to decide?”

  • understand the main choices available (what, where, when, how):

    • “Can you tell me about what your options are?”
    • “Is doing nothing an option?”
    • "What would these treatments involve?" 

  • weigh up those choices, including benefits and risks:

    • “What are the benefits and risks for these options?”
    • “What would be the benefits and risks of doing nothing?”
    • "Which option is best for you?"

  • make a decision and be able to communicate this:

    • “So what are you doing to do?”

  • understand the ramifications of the decision:

    • “What was important to you in making that decision?”
    • “How did you balance the other choices and come to this decision?”

Summary points16

  • Always presume an adult patient has capacity.
  • Capacity is decision specific.
  • Don’t base your decision on appearances.
  • assess the decision-making ability, not the decision.
  • Emergency or substitute decision-making is a last resort.

Dr Julian Walter
Medico-legal Adviser, MDA National


  1. National Quality Forum: Serious Reportable Events In Healthcare: A Consensus Report 2011 Update A (Glossary). 2011. Available at: at page B2. 
  2. Attorney General’s Department NSW. Capacity Toolkit. Sydney: NSW Attorney General’s Department, 2008, p10.
  3. e.g. Gillick v West Norfolk and Wisbech Area Health Authority [1985] (1985) 3 All ER 402. Available at:
  4. Gardner PA [et al]. Financial Capacity in Older Adults: A Growing Concern for Clinicians. MJA 2015;202(2):82. Available at:
  5. Tunzi M. Can the Patient Decide? Evaluating patient capacity in practice. American Family Physician. 2001;64(2):299-308. Available at:
  6. British Medical Association. Mental Capacity Toolkit at CARD 4, point 4. Available at:
  7. Eagle K, Ryan C. Mind the Gap: The Potentially Incapable Patient Who Objects to Assessment. ALJ 2012;86:68. Available at:
  8. Purser K, Rosenfeld T. Evaluation of Legal Capacity by Doctors and Lawyers: The Need for Collaborative Assessment. MJA 2014:201(8):483-485. Available at:
  9. Ontario Ministry of the Attorney General. Guidelines for Conducting Assessments of Capacity. Toronto: Ontario Ministry of the Attorney General, 2005.
  10. Hamilton B, Cockburn T. Assessment of Capacity: Disciplinary Issues and Potential Liability. Proctor March 2009:15. Available at:
  11. MacArthur Research Network. MacArthur Competence Assessment Tool: A widely researched commercial tool used in the US with specific variants, e.g. MacCAT-T (Treatment decisions), MacCAT-CA (Criminal Adjudication); MacCAT-CR (Clinical Research). Available at:
  12. Capacity Australia. Mini-legal kits. Available at:
  13. For example – Aid To Capacity Evaluation (ACE). Available at:
  14. This will be addressed in a future Defence Update article.
  15. Advance Care Planning and Advance Care Directives (Medico-legal Feature Pull-out). Defence Update Autumn 2014:9–12.
  16. Attorney Generals’ Department NSW. op. cit., p27

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