Mental Capacity Case

RB Greenwich v CDM

Newton J


CDM was a 64 year old woman with a range of diagnosed personality disorders and physical health problems who was deprived of her liberty against her wishes in a care home.  She was found by the court to have capacity to decide where to live and to make various other decisions, but to have fluctuating capacity with regard to the management of her diabetes.  Readers may recall that CDM's case went to the Court of Appeal at the end of 2018 on the question of fluctuating capacity, but in light of fresh medical evidence the Court of Appeal decided that the matter needed to be dealt with fully by a first instance judge.  This judgment is the decision of Newton J, in which the initial decision that CDM's capacity to manage her diabetes fluctuated as a result of her personality disorder, was more fully considered, with the benefit of additional expert evidence.

Newton J summarised the issues before him as follows:

  1. Whether the assessment of capacity to make decisions about diabetic management or "the matter" in relation to which CDM is being assessed is one macro-decision which encompasses all of the many micro-decisions that CDM is required to make when managing her diabetes, or, whether CDM's capacity should be assessed in respect of each micro-decision or group of micro-decisions.
  2. In the light of that determination, whether the presumption that CDM has capacity to make decisions about her diabetes has been rebutted, and if so on what basis.
  3. If I conclude that as a matter of fact CDM's capacity to make decisions about any aspect of her diabetes management fluctuates, what preparations the court can and should make to reflect that finding.
The court heard long and complex evidence about CDM's capacity.  In short, the two experts instructed (one a psychiatrist and one a psychologist) agreed that the management of CDM's diabetes had to be viewed at a macro level, or as a group of micro-decisions, because the decisions had to be consistent and coherent with each other over time, and because decisions at one time would be affected by decisions taken earlier.   CDM did not understand that she was at risk of death when her insulin levels were very poorly controlled, and her emotional dysregulation as a result of her personality disorders was frequent, and affected her ability to retain and to weigh information.  The conclusion of Dr Beck, the expert psychologist, was that:

There may be some times when CDM makes a decision in relation to the management of her diabetes where she understands the elements of the decisions being made, retains the information, weighs it up without the defect of a dysregulated emotional state, and communicates this effectively. However, these times, if they occur, are infrequent and unpredictable. If this is fluctuating capacity, then CDM has fluctuating capacity to manage her diabetes.

The Official Solicitor (on behalf of CDM) sought to argue that the diabetes management decisions should not be treated as one decision, as otherwise CDM would have her capacitous micro-decisions overridden.  The Official Solicitor proposed that:

the appropriate way of "defining the matter", when assessing diabetic management, is not to accept the macro or micro-decision approach, but to group them together and consider whether CDM has the capacity:

  1. To make decisions about controlling her diabetes and diet.
  2. To make decisions about treatment for her diabetes, which is in turn subdivided into three separate decisions:
  1. The capacity to make decisions about testing and the blood sugar at right glucose levels, which encompasses submissions about weighing and testing blood glucose levels.
  2. The capacity to make decisions about treatment being offered for her diabetes but falling short of life-saving treatment. Treatment by insulin as required. And,
  3. The capacity to make decisions about life-saving treatment for diabetes, which will include, in some cases, taking insulin or admitting herself and taking her to hospital.
Newton J rejected this analysis, holding that:

a) on the assessment of capacity to make decisions about diabetes management, in all its health consequences, the matter is a global decision, arising from the inter dependence of diet; testing her blood glucose and ketone levels; administration of insulin; and, admission to hospital when necessary in the light of blood glucose levels. And

b) that CDM lacks the capacity to make those decisions, and having regard to the enduring nature of her personality disorder which is lifelong and therefore unlikely to change.

Newton J:

acknowledge[d], as do the experts, that there may be occasions when CDM has the capacity to make micro-decisions in respect of her diabetes and occasions when she does not, i.e. that her capacity does in fact fluctuate. However, if the court accepts the expert's opinions, as I do, and approaches the matter on the basis of their conclusions, logically, legally and practically, it is a macro-decision, and CDM lacks capacity to take the macro-decision, the issue of fluctuating capacity simply does not arise.

More broadly, Newton J did not think it:

necessary or helpful to draw inferences or parallels on examples of other conditions or other classes of individuals, since the interrelationship between the micro and macro-decisions still needs to be decided, having regard to a particular individual in particular circumstances, and having regard to their particular condition. No two people self-evidently are ever the same, their condition the same condition, or the circumstances the same. The elements in relation to CDM's own particular conditions are unique to her. CDM has diabetes which is not unique to her, being shared with many other millions of people in the United Kingdom, but as an individual the factors are unique.


After a long route through the courts and a substantial volume of evidence, the conclusion for CDM was that she lacked capacity to manage her diabetes, viewed on a global basis, even though there would be times (which could easily be identified) when she could make individual decisions about aspects of the management of her condition with capacity.

This case could be contrasted with that of United Lincolnshire Hospital NHS Trust v CD [2019] EWCOP 24, in which Francis J held that where the circumstances under which the woman in question would lack capacity to make decisions about birth arrangements were sufficiently clear that it was possible to make a 'contingent' declaration about what could then happen in her best interests at that point.  In this case, however, Newton J noted that:

during the course of evidence, Dr Beck was asked for more guidance as to the signs when CDM becomes emotionally dysregulated and whether she has lost capacity in respect to either of the micro-decisions but, Dr Beck was simply unable to do so, because it was impossible to do so.

In CDM's case, therefore, every action in relation to the management of her diabetes would fall to be considered by reference to her best interests, taking into account, of course, her wishes and feelings.

On the facts of the case before Newton J, the practical benefits of taking this global approach were obvious – clarity about the ability to intervene to provide treatment to CDM to prevent her from becoming seriously ill, or to ensure that she was admitted to hospital when her condition is so serious that she might die.

However, as Newton J identified, the decision was highly fact-specific; it is also unlikely to be capable of easy application to other scenarios.

[1] Both Katie and Alex having been involved with this case, this summary has been prepared by Tor.