Tribunal of Commissioners 25 November 2005
Case Nos CDLA/2879/2004 and CDLA/2899/2004
but in the context of care component and lower rate mobility component, neither of which required a distinction to be made between physical and mental disablement. The evidence on behalf of the Secretary of State was that general learning disability was due to an arrested or incomplete development of the mind, but that it is usually accepted by decision makers as a physical disablement: by contrast, specific learning difficulties are treated as mental disablement (see paragraph 23 of that decision).
74.In R(M) 2/78 (see paragraphs 28 to 32 above), it was held by the Chief Commissioner that the medical appeal tribunal had not erred in law in finding that Down’s syndrome was a physical disorder because it was due to faulty genetic inheritance. We were told by Mr Maurici on instructions that the Secretary of State regards Down’s syndrome as a physical disorder. In CSDLA/894/2001, Mrs Commissioner Parker held that limitations on walking ability resulting from autism are to be regarded as due to physical disablement because autism is due to a chromosomal abnormality. These cases took the analysis right back to the level of genes and chromosomes. Once the level of genes, chromosomes and chemical changes affecting the brain is reached, it may well be that, if the relevant criterion is cause rather than manifestation, any mental illness could be categorised as a feature of the claimant’s physical condition as a whole.
75.The difficulty in distinguishing between the physical and the mental was a major reason for the effective abandonment of the distinction between physical and psychiatric injury in the context of tortious liability. As long ago as 1943, Lord Macmillan said in Bourhill v Young  AC 92 at page 103:
“The crude view that the law should take cognisance only of physical injury resulting from actual impact has been discarded, and it is now well recognised that an action will lie for injury by shock sustained through the medium of the eye or ear without direct contact. The distinction between mental shock and bodily injury was never a scientific one, for mental shock is presumably in all cases the result of, or at least accompanied by, some physical disturbance in the sufferer’s system. And a mental shock may have consequences more serious than those resulting from physical impact.”
More recently, in Page v Smith  1 AC 155 at page 188, again in the context of liability for negligence, Lord Lloyd said:
“In an age when medical knowledge is expanding fast, and psychiatric knowledge with it, it would not be sensible to commit the law to a distinction between physical and psychiatric injury, which may already seem somewhat artificial, and may soon be altogether outmoded. Nothing will be gained by treating them as different “kinds” of personal injury, so as to require the application of different tests in law.”
76.It is not for us to attempt to resolve all these issues. For the present purpose, the important point is that there appears to be no logical or consistent stopping place, short of Mr Commissioner Monroe’s “last analysis”, in following back mental or psychological factors to an ultimate physical cause
77.However, it is right that we point out that, in the benefits field, as recently as 1995, Parliament made use of the distinction between physical and mental in the context of the all work test (now called the personal capability assessment) for determining incapacity for work