Ethics toolkit for medical students

Getting consent from adults without capacity as a medical student

Location: England Wales Northern Ireland
Audience: Medical students
Updated: Friday 1 May 2020

Here, we look at some of the ethical and legal issues related to making health decisions on behalf of incapacitated adults. In England and Wales, decision making in this area is governed by the Mental Capacity Act (2005) (MCA).


How to proceed if the individual lacks the capacity to consent?

We have seen previously in the toolkit the importance of respecting autonomous choices and how this is expressed in the requirement to seek informed consent from patients. If patient consent renders an intervention legally and ethically acceptable, how are we to proceed where the individual lacks the capacity to consent? (Where the individual is a child and unable on the grounds of immaturity to make a decision, those with parental responsibility can consent on the child’s behalf). Where adults lack capacity other people will have to make the decision for them.

Although you will not directly be involved in assessing capacity or making ‘best interests’ decisions, demographic changes mean that, throughout your future career, many of you will be looking after adults who may be suffering from some degree of cognitive impairment.


Food for thought

Why does capacity matter?

Our right to determine what happens to our bodies is straightforwardly vital to our wellbeing. In doctor-patient relationships this right is sometimes translated as the moral obligation on doctors to show respect for persons and their autonomous choices. This right, and its corresponding obligation, are at the moral centre of medical practice.

Respect for persons includes both respect for their choices and a concern for their welfare. When someone becomes incapable of making self-governing decisions, their decision-making rights give way and concern for their welfare comes to the fore. A decision that someone lacks capacity is therefore a serious one involving the loss of fundamental human freedoms. In contrast, a failure to identify that someone lacks the capacity for autonomous choice can also expose them to serious harms.


What is mental capacity and why is it important?

In addition to being voluntary and informed, autonomous decisions require the possession of sufficient mental capacity. In English law all adults are presumed to have the capacity to make decisions on their own behalf. Legally, capacity is given a common sense definition referring straightforwardly to our ability to take actions or make decisions that influence our lives. A decision that adults lack capacity is obviously a significant one. It strips us of our right to control our lives in relation to the decision in question.


When does an adult lack capacity?

Before adults can be assessed as lacking capacity two things have to be established. First, it has to be shown that the adult is suffering from some sort of impairment or disturbance of the mind or brain. This is known as the 'diagnostic' criterion. It can include factors such as mental illness or the cognitive decline associated with Alzheimer’s disease. It can also refer to short term factors such as extreme intoxication by drugs or alcohol.

Without the existence of such an impairment an adult cannot be assessed as lacking capacity. Having identified the impairment it then has to be established that it prevents the individual from making the relevant decision.

This involves identifying whether the individual can:

  • understand the information relevant to the decision
  • retain the information long enough to be able to make the decision
  • use or weigh the information; or
  • communicate the decision by any means.

If an individual is unable to do any one of these then he or she is deemed to lack decision-making capacity.


How much capacity is enough?

Although there will be times when it is obvious that someone lacks capacity – they may be unconscious – in the majority of cases, people retain the capacity to make some decisions. One of the really challenging questions is the extent to which a person’s capacity must be impaired before he or she loses their right to make a decision.

There is no straightforward answer to this. UK law takes a functional and decision-specific approach. It asks if the individual has the capacity to make a specific decision at a specific time, not whether he has the ability to make decisions generally. Ordinarily, the more complicated or serious the decision the greater the evidence of capacity required to make it and the more thorough and searching the assessment of capacity.

Capacity/incapacity are not concepts with clear…boundaries. They appear on a continuum which ranges from full capacity at one end to full incapacity at the other end. There are, therefore, degrees of capacity. The challenge is to choose the right level to set as the gateway to decision-making and respect for persons…
Michael Gunn

What does the law say?

"The general rule of English law, whatever the context, is that the test of capacity is the ability (whether or not one chooses to exercise it) to understand the nature and quality of the transaction."

Justice Munby. Re MM (an adult) [2007] EWHC 2003 (Fam)


Who should assess capacity?

There is a presumption in English law that all adults have the capacity to make decisions relating to their life. Where there are doubts about capacity and consent to medical treatment is required, the health professional proposing the treatment needs to decide whether the patient has the capacity to consent.

In some circumstances, such as where there are genuine doubts about capacity and the decision is a serious one, expert advice from a psychiatrist or psychologist with particular experience in assessing capacity should be sought. Overall responsibility remains, however, with the health professional proposing the treatment.


How can treatment lawfully be provided to adults who lack the capacity to consent?

There are a number of ways in which treatment can be provided lawfully to adults who lack the capacity to make the decision.

  • Where an adult has no one to make a decision on his or her behalf, treatment can be provided where it is both necessary and in the patients best interests – a ‘best interests’ decision.
  • Where the incapacitated adult has previously nominated someone to make the decision – a welfare attorney.
  • Where the Court of Protection has appointed a deputy to make the decision.
  • Under mental health legislation.


What is a ‘best interests’ test?

Decisions taken on behalf of someone who lacks capacity must be taken in his or her best interests. A best interests test is an objective test of what would be in the person’s actual best interests, taking into consideration all relevant factors. A best interests test is not a ‘substituted judgment’ test. A substituted judgment test seeks to identify what the patient would have wanted and to decide accordingly. A best interest test takes the patients wishes into account where they are known, but they may not be determinative.

Factors that need to be taken into account when making a best interests test include the following:

  • the extent of the incapacitated person’s ability to participate in the decision
  • the likelihood that the person will regain capacity in sufficient time to be able to decide personally
  • the person’s past and present wishes and feelings
  • his or her beliefs or values where they would be relevant to the decision
  • the benefits and burdens of the decision.

An important part of any best interests assessment is, where possible, a discussion with those close to the individual in order to try and establish those things that were important to the patient and which may have an impact on the decision.


Advance decisions refusing treatment

Competent adults can refuse specified treatment for a time in the future when they may lose capacity. This is called an advance decision refusing treatment, sometimes known colloquially as a living will. Patients can only refuse treatment by means of an advance decision, they cannot commission treatment in advance.

An advance decision refusing treatment is binding where:

  • the person had capacity and was aged 18 or over when he or she made it
  • it specifies, in lay terms if necessary, the specific treatment to be refused and the particular circumstances in which the refusal is to apply
  • the person making the decision has not subsequently withdrawn the decision or appointed a proxy to make it
  • the person has not subsequently done anything clearly inconsistent with the decision
  • if the decision relates to life-prolonging treatment it must be in writing, signed and witnessed and contain the statement that the decision is to apply even if life is at stake.



  • Grisso and Appelbaum – Assessing competence to consent to treatment
  • Law Society and BMA – Assessment of Mental Capacity