The Mental Health Act attaches great significance to the “nature or degree” of mental illness. Any psychiatrist who has ever appeared before the First Tier Tribunal will be well aware of the importance of these terms in the Tribunal’s decision making.
In broad terms, ‘nature’ is the course of a disorder and the consequences of it while ‘degree’ is the presentation at that point in time.
The Explanatory Notes for the Mental Health Act 2007 note that “Case law has established that “nature” refers to the particular mental disorder from which the patient is suffering, its chronicity, its prognosis, and the patient’s previous response to receiving treatment for disorder. “Degree” refers to the current manifestation of the patient’s disorder (R v Mental Health Review Tribunal for the South Thames Region ex p. Smith  C.O.D. 148).”
When undertaking assessments under the Mental Health Act in the community, in some cases the patient appears to be symptom free and there is little evidence of ‘degree’. However, in some cases it is necessary to rely on the ‘nature’ of the disorder, particularly where there is an established diagnosis and where there would be risk to the patient or others if they were not treated. Commenting on this very issue, Lady Justice Hale, said, “There are of course mental illnesses which come and go, but where there is a chronic condition, where there is evidence that it will soon deteriorate if medication is not taken, I find it impossible to accept that that is not a mental illness of a nature or degree which makes it appropriate for the patient to be liable to be detained in hospital for medical treatment if the evidence is that, without being detained in hospital, the [...]