End of Life Law - Capacity and consent to medical treatment factsheet

Factsheet: Capacity and Consent to Medical Treatment

A person may consent to or refuse medical treatment if they have decision-making capacity. Generally health professionals must obtain consent before medical treatment can be provided to an older person. This factsheet explains the law on decision-making capacity, and consent to medical treatment.

Clarifying the law

This factsheet explains:

  • When consent to treatment is required, and when it will be valid
  • When a person will have capacity to make decisions about medical treatment
  • Whether a person with capacity can make a decision that others disagree with
  • Whether a person’s capacity can change over time

Consent to medical treatment when a person has capacity

A person with decision-making capacity has the right to decide what is or is not done to their bodies. This means they can consent to medical treatment, or refuse it.

When is a person’s consent to treatment required?

Valid consent should be obtained from a person with capacity prior to examining them or providing medical treatment.

A health professional who examines or treats a person without consent could be liable under civil or criminal law (for example, being charged with assault), or be subject to disciplinary action.

Consent is not required from a person when:

  • emergency treatment is needed to save the person’s life, prevent serious damage to health, or prevent significant pain and distress, and neither the person nor their substitute decision-maker can provided consent; or
  • they have impaired decision-making capacity (discussed below). In this situation, consent can be provided in an Advance Care Directive or by a substitute decision-maker. This is discussed further in the End of Life Law Toolkit’s Advance Care Directives and Substitute Decision-Making factsheets.

What is valid consent to treatment?

For consent to be valid:

  • the person must have capacity to consent;
  • the person must provide that consent freely and voluntarily. This means the decision is made without undue influence, coercion or manipulation; and
  • the consent must apply to the treatment to be given.

Appropriate advice and decision-making support from the person’s family and health professionals will not be undue influence so long as the person is still making the decision they want. However, a person changing their treatment decision when another person is present may alert a health professional to possible undue influence.

Are there formal requirements for consent?

Consent can be given verbally or be implied (for example, if a person offers their arm so that a nurse can take blood). Sometimes, for example, before a major procedure, it may be appropriate to obtain written consent. A health professional should also provide information about treatment risks and consequences, and any other information a person needs to provide consent. This is part of a health professional’s duty of care to the person they care for, as well as good practice. Not doing this could result in civil liability for not warning about an adverse outcome.

Decision-making capacity

When does a person have capacity?

All adults are presumed to have capacity to consent to or refuse treatment, unless it can be shown that they do not.

A person will have capacity for a medical treatment decision if they can:

  • comprehend and retain the information needed to make the decision, including the consequences of the decision; and
  • use and weigh that information as part of their decision-making process.

Information about treatment can include the proposed treatment and alternatives, and the consequences and risks of different treatment options.

Guardianship and medical treatment legislation in each State and Territory sets out similar capacity tests, but some have additional requirements. e.g. the person must also be able to communicate the decision in some way.

Learn about the requirements for a person to have decision-making capacity in your State or Territory at End of Life Law in Australia


Supported decision-making

It may be possible in some situations for people with cognitive disability to have capacity for medical decisions if they have appropriate decisionmaking support. In Victoria and Queensland a person will have decision-making capacity if they can make a medical treatment decision with appropriate support.

Support for decision-making can include a health professional adjusting their language to communicate about treatment in a way the person understands; using visual aids; or giving the person more time to process and ask questions. Learn more about supported decision-making in Victoria and Queensland at End of Life Law in Australia:

Who decides whether or not someone can make their own decisions?

Generally capacity is assessed by a person’s doctor or a medical practitioner with expertise in capacity assessment, e.g. a psychologist, but in some cases, such as if there is doubt about a person’s capacity, a court or tribunal might be asked to decide this.

What if a person makes a decision that others disagree with?

A person with capacity can make a decision that others disagree with, and that decision must be respected. A person does not lack capacity just because they make a decision someone disagrees with, or that a health professional considers is not in the person’s interests.

For example, a person with capacity can refuse life-sustaining medical treatment, even if it is recommended by a doctor.

Or, they can refuse to be transferred to hospital, even if a health professional or family member thinks they should go

This is because capacity relates to the person’s ability to make a decision, not what decision they make. However, an unwise or unusual decision may be a prompt for health professionals to check a person’s capacity, for example, by referring the person to a medical practitioner with expertise in capacity assessment.

Learn about refusals of treatment in the End of Life Law Toolkit factsheet Withholding and Withdrawing Life-Sustaining Treatment. Refusal of hospital transfer is discussed in the Emergency Medical Treatment factsheet.

Can a person have capacity for some decisions but not others?

Some medical treatment decisions are more complex than others. A person may have capacity to make a simple decision about medical treatment but not a more complex one.

For serious decisions, such as refusing medication which may be necessary to keep a person alive, the process of understanding, retaining and weighing the information (and risks involved) will be more complex than for more minor decisions, such as consenting to a blood test.

Can a person’s capacity change over time?

A person’s capacity to make a decision can also change over time. For example, a person in aged care may have fluctuating capacity because of delirium, some forms of dementia or mental illness.

Capacity will be judged at the time a treatment decision is required. A person may be able to make a decision at one time of day, but not at another time on the same day.

It is important to remember that a person does not lack capacity just because they have a medical condition, mental illness or intellectual disability. They can make their own treatment decisions so long as they meet the test for decision-making capacity.

‘Capacity is decision specific so even if you have been diagnosed with dementia, you may still have capacity to make all or at least some of your own decisions, especially if you have been diagnosed with early dementia.

Decision-making capacity may fluctuate over time and depend on the context such as the time of day, location, noise, stress or anxiety levels, medication, or infection’.

Dementia and your legal rights (780kb pdf), Alzheimer’s Australia, 2016

  • Key points to remember
  1. A person with capacity must give valid consent before medical treatment can be lawfully provided to them. Treating without consent could lead to civil or criminal liability, except in some limited circumstances.
  2. Consent to treatment is valid only when the person has capacity, gives consent freely and voluntarily, and the consent relates to the proposed treatment.
  3. An adult is presumed to have capacity to consent to medical treatment, unless it can be proved that they do not.
  4. A person will have capacity for a medical treatment decision if they are able to comprehend and retain the information needed to make the decision, and can use and weigh that information when deciding.
  5. An adult with capacity can make decisions that others disagree with, including to refuse life-sustaining treatment, or not to be transferred to hospital.
  6. A person’s capacity should be assessed at the time a treatment decision is needed. A person may have capacity for some decisions but not others, and their capacity to make a decision can change over time.

Page updated 1 June 2021