I’ve been completing a paper on the location of rationality in medical decision-making and the relationship it has to decision-making capacity.
Decision-making capacity is now a critical concept in English law because it underpins when treatment in an individual’s best interests may be authorised under the Mental Capacity Act.
But the question I want to explore here is what kind of thing is decision-making capacity? It is clearly an assumption of the law that the capacity to make a decision inheres to the individual even if the reason the person lacks capacity relates to undue influence placed upon her by another (see A Local Authority v A). But what kind of property of the person is decision-making capacity?
It could be like height. Height is a straightforward property of bodies. Measurement may still be problematic, because we still have to choose a unit to express the measurement in: inches, cm or hands if the thing you are measuring is a horse. But the idea is uncontroversial.
But decision-making capacity involves at least two parameters. To make a decision I have to understand and retain the information and I have to be able to use and weigh the information in the process of deciding. In the MacCAT-T, a validated clinical assessment tool for measuring decision-making capacity three parameters are assessed: understanding, reasoning and appreciation.
So perhaps decision-making capacity is more like the size and shape of my body. My body has a weight which like my height can be measured in pounds or kilograms. But it also has dimensions. If I only want to know my weight then kilograms are an adequate measurement. But if I want to know if clothes are likely to fit I need to know my dimensions.
And even armed with information about the dimensions of my body I may still struggle to find clothes that fit. Clothes have properties of their own which determine their fit such as their fabric and cut.
To rationalise this process for women the clothing industry applies labels to make it easier for purchasers to work out which ones might be worth trying. Clothes are labelled 8, 10, 12 etc. But the labels can become a source of confusion if they are mistaken for information about the woman’s size. It is widely accepted that it is desirable to fit into smaller clothing sizes because our society values thinness, the number 12 must be better than 14. But sizes evolve, they change over time, according to some people because womens body shapes change and manufacturers make clothes to fit a normal distribution across the population. Others argue this phenomenon is best described as ‘vanity-sizing’ because it is motivated by the manufacturer’s desire to flatter their customers that they remain a size 10 even when they have changed shape or gained weight.
Either way labels like 8, 10 and 12 are a clothing industry construction which women might reasonably perceive as containing more information about their bodies than they actually do [note I have no reason to think the phenomenon is exclusive to women but it is less likely to affect men whose clothing is still predominently sold by reference to physical dimensions].
Finally, how do we understand if a body’s mass is healthy. Here we reach the most troubled water of all. For this the standard tool is the Body-Mass Index, famously based on a equation developed in the mid-19th century to enable comparisons across whole populations. It only began to be used in the clinical assessment of individuals in the late 20th century. The BMI is a troublesome tool because, as with the MacCAT-T, it involves measurements, calculation and then an application to the individual. This application to the individual is based on standardised tables based on actuarial assessments of risk associated with different BMIs carried out in the 1950s. There is ongoing controversy over whether the standard cut-off point for assessing a BMI as overweight actually reflects a significant level of risk to the individual’s health.
Assessments of decision-making capacity run into the same problems, with the added complexity that there is no tool available to measure decision-making capacity which has been as widely validated as the BMI (and I’m willing to assert will not be since the idea is vastly more complex). The MacCAT-T does not give an output in terms of yes or no. It merely provides some numerical outputs concerning understanding, appreciation and reasoning which the clinician can take into account alongside the wider knowledge of the patient’s history, the magnitude of the decision to be taken and any other relevant factors.
Comparing the measurement of decision-making capacity with BMI exposes the socially contestable dimensions of the idea. There will always be borderline cases because the assessment relies ultimately on a judgement that this individual has crossed a threshold which another has not. But unlike BMI, there is no comfortable possibility of recourse to international committee of experts who will defend the idea that 25 is an appropriate threshold for the definition of ‘overweight’. In borderline cases resolution can only ever be achieved through the application of more clinical judgment.
And the problem of dimensions of the body resembles the problems created by poor information sharing leading to lousy therapeutic relationships leading to mistrust. The person assessed as lacking capacity is like the woman who no longer knows if she is an 8, 10 or 12. Capacity assessment can and should be a robust process founded upon transparent norms which are communicated early on. But it frequently is not.
But does this mean that capacity isn’t just a property of the person after all. It seems to me the answer must be yes and no. We could argue that capacity is interactive and that with support at any given time most people could make a decision. I respectfully disagree. I suspect that more people can make decisions than we adequately support currently. But there are clearly many circumstances where decision-making is impossible. I have epilepsy and sometimes experience psychotic symptoms and I’d say seizures, the immediate post-ictal state and acute psychosis fundamentally undermine my decision-making capacity.
But even if we assume, as I do, that decision-making capacity is at least sometimes a property of minds as well as the social world the tools we use to measure it are inherently social constructions. Just like the tools we use to measure the body. So which tools we select and when we choose to employ them suddenly become very politically-laden decisions.
My own view is that the idea of capacity is as socially constructed as the idea of bodyweight but this does not undermine the need to assess it or make decisions on the basis of these assessments (or as my favourite social theorist Niklas Luhmann put it enigmatically ‘Reality may be an illusion but the illusion itself is real’). But we need to be constantly monitoring the way in which social and political factors interact with our understanding of what it means to have capacity to ensure that current assessment practices remain adequate.