This paper argues that in medical discourse, there is insufficient unanimity of opinion with regards to the time at which an accurate diagnosis of PVS can be made and that clearly, there is an incomplete medical knowledge of the PVS condition. The judiciary chooses neither to question medical opinion that patients can be considered to be in PVS despite a failure to satisfy the diagnostic criteria, nor medical opinion that patients in ‘near PVS’ will never recover. It is apparent from an examination of the judgements given in PVS cases that the law does not ascribe such individuals with full human status. Such a legal position is particularly problematic in ethical terms when applied in cases involving patients who are in a ‘near PVS’ position, and in the light of evidence that some PVS diagnoses are inaccurate. The application of the best interests test in PVS cases results in the adoption of a paternalistic, objective approach that fails to respect the former competent individuals whom PVS patients once were. If, alternatively, the substituted judgement test were to be adopted, the principle of individual autonomy would become central to the question of whether PVS patients’ treatment should be withdrawn. Furthermore, the application of this test would also ensure that PVS patients continue to be viewed as ‘persons’.