Capacity and Competence


Capacity and competence are terms that are often used interchangeably

  • Capacity is a functional term that refers to the mental or cognitive ability to understand the nature and effects of one’s acts
  • Competence is a legal term that can be defined as being “duly qualified: having sufficient, capacity, ability or authority” — in practice it requires health professionals to perform a functional test of competence to examine the ability of the particular patient to consent to the specific treatment being offered


  • In Australia at common law and under some statutes, adults (people over 18) are presumed to be competent, although it is possible to rebut the presumption by showing that an adult lacks competence
  • In some states the presumption of competence has been extended to people younger than 18
  • The presumption is reversed for children — they are presumed to be incompetent unless they can prove otherwise


Demonstrating competence involves 4 important elements, the ability to:

  1. maintain and communicate a choice
  2. understand the relevant information
  3. appreciate the situation and its consequences
  4. manipulate the information in a rational fashion


  • Testing understanding is extremely difficult
  • the law does not require any specific types of tests of competence
  • Useful questions to ask (always ask about BRAN: benefits, risks, alternatives, and no treatment):
  1. What is your present physical condition?
  2. What is the treatment being recommended for you?
  3. What do you and the doctor think will happen to you if you decide to accept treatment? (benefits)
  4. What do you and your doctor think will happen to you if you do not accept the recommended treatment? (risks)
  5. What are the alternatives available (including no treatment) and what are the possible consequences of accepting each? (alternatives, including no treatment)


  • Cognitive impairment is widely under-recognised, up to 60% of people with mild-moderate cognitive impairment are undiagnosed
  • Competence can vary over time
  • A mental illness does not necessarily imply a lack of capacity to consent, if the above elements can still be satisfied
  • Competence is specific and/or can vary with specific tasks — a patient may be competent to consent for a simple procedure but not a complex procedure
  • The patient’s decision need not be one that others would regard as reasonable, but it must involve a process of reasoning
  • improvements in the patient’s level of comfort may improve competence – giving them time to think, allowing the support of friends and relatives, treating any reversible symptoms, such as pain, that may be compromising their capacity, or putting them in a quiet room or somewhere with a non-threatening atmosphere
  • comprehensive testing (e.g. neuropsychiatric testing) and extensive corroborative testing is advised if there is disagreement between health professionals, or between them and patients or guardians
  • the more serious the decision that has to be made, the greater the care needed to ensure that competence can be presumed
  • simple cognitive tests such as the Mini-Mental State Examination are flawed (e.g. culture-specific, does not adequately address individual cognitive domains)
  • Children (see Consent and competence in children)
  • the issue of obtaining consent from a person to assess their capacity when they potentially lack the capacity is a dilemma!

References and Links


Journal articles and textbooks

  • Purser KJ, Rosenfeld T. Evaluation of legal capacity by doctors and lawyers: the need for collaborative assessment. Med J Aust. 2014 Oct 20;201(8):483-5. PubMed PMID: 25332040. [Free Full Text]
  • Snow HA, Fleming BR. Consent, capacity and the right to say no. Med J Aust. 2014 Oct 20;201(8):486-8. PubMed PMID: 25332041. [Free Full Text]
  • Stewart C, et al. The Australian Medico-Legal Handbook (1st edition), Elsevier,2007 [Google Books Preview]

Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of three amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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