Large et al ^{Reference Large, Ryan and Callaghan1} draw valuable attention to the flawed information on which the Supreme Court based its decision to uphold the appeal of Rabone against the Pennine Care NHS Foundation Trust, ² identifying a number of well-recognised biases that prompted the judges to overvalue the risk of suicide by a factor of 40.

Another significant bias that is often overlooked in post-hoc analyses of serious untoward events concerns the value framework of the assessor, described with precision by Kahneman & Tversky. ^{Reference Kahneman and Tversky3} Expert witnesses, although owing a primary duty to provide valid information to the court, are nevertheless instructed by legal professionals who are obliged to adopt either a defensive or offensive stance given the inherently adversarial nature of the legal system. The differing value frameworks that this provides are evident in the discrepancy in the evaluations of the 'immediate risk’ posed by Ms Rabone of between 70% (as estimated by the claimants) and 20% (as estimated by the defendants). That such a spectacular discrepancy might point to the meaninglessness of a numerical approach seems to have escaped consideration.

Instead, deferring to the expert status of the witnesses, the Court appears to have dealt with this variance by taking the most conservative figure as the valid baseline for their consideration.

The judgments derived from such flawed considerations do little to help those who daily face the difficult task of attempting to 'second guess’ (i.e. to anticipate) the intentions and behaviours of a mind disturbed by what the Court termed 'a recurrent depressive disorder’.

Most mental health professionals appear to agree that a sincere wish to die is one of the less common reasons for the issue of a suicidal threat. ^{Reference Salter and Turner4} Unless such considerations are taken into account by those who define the laws by which our best practices are shaped and defined, misinformed legalism will continue to exert an increasingly demoralising effect on those who do their best in a very difficult situation.

The present judgment will, in all likelihood, lead to an increase in the detention of individuals with depression against their wishes in services that, especially in the current social and economic climate, may not be as well equipped to reduce risk (in either the short or long term) as either judges or the general public may like to think. Practical measures derived from ethics and common sense may be of more help here than actuarial procedures.

Ms Rabone appeared to had given a clear commitment not to self-harm at the time of her departure. It is unclear how much weight was given to this fact by the Court, but it presumably carried considerable weight in the mind of the unfortunate psychiatrist who granted her informal leave. A useful standard by which to judge the wisdom of such a decision might involve contemporary recording of unequivocal evidence of future orientation. At its simplest, this could comprise clear recording of the patient's agreement not to act on impulses of self-harm, accepted as valid regardless of the private discomfort of those involved, alongside an equally clear recording of the patient's agreement to return to care at a clearly agreed place and point in time. All individuals failing these tests should be subject to consideration for legal detention.

To this, a prudent psychiatrist might add a written note setting out the grounds for his or her decision, relating the individual circumstances of the case at hand. Such an entry in the case notes made at every significant point during the patient's progress would be time consuming and might read, in effect, as an open letter to a future court, but its use would seem to be the most appropriate response to the judgment handed down by the Supreme Court on this occasion.