56/94

     JMe/1/LM      					Commissioner's File: CI/34/93
      
     							DSS File: Not Known

SOCIAL SECURITY ACTS 1975 TO 1990 
SOCIAL SECURITY ADMINISTRATION ACT 1992
     
APPEAL FROM DECISION OF MEDICAL APPEAL TRIBUNAL ON A QUESTION OF LAW
     
DECISION OF THE SOCIAL SECURITY COMMISSIONER
     
Name:

Medical Appeal Tribunal: 

Original Decision Case No:
     
      [ORAL HEARING]
     
      1. The claimant's appeal is allowed. The decision of the Bristol medical appeal tribunal dated 29 November 1991 is erroneous in point of law, for the reasons given below, and I set it aside. The appeal is referred to a differently constituted medical appeal tribunal for determination in accordance with the directions given in paragraphs 14 and 24 below (Social Security Administration Act 1992, section 48(5)).
     
      The background
     
      2. The claimant injured his right knee in an industrial accident on 5 February 1990. On 28 November 1990 he had an arthroscopic menisectomy of the right knee. He claimed disablement benefit on 15 April 1991. The adjudicating medical authority (AMA) on 15 May 1991 found the loss of faculty to be impaired movement with pain in the right knee joint and assessed the resulting disablement at 12% from 20 May 1990, with at least 1% disablement to continue for life. In reaching the figure of 12% the AMA had started with a gross figure of 15% and applied an offset of 3% for pre-existing arthritis. That conclusion seems to have been based solely on the claimant's evidence to the AMA and its examination, which found "marked crepitus on active flexion" in the right knee joint. In the box marked "Remarks" the AMA recorded "The degree of crepitus present in the Rt knee jt must be a result of a long standing osteoarthritis".
     
      3.   The claimant appealed against that assessment. The medical appeal tribunal (MAT) heard the appeal on 29 November 1991. the MAT had before it an extract of hospital case notes (now at pages T1 3 and T1 4 of the papers before me) and a copy of a report dated 17 August 1991 by Mr A.W. Jowett, a consultant orthopaedic surgeon (now at pages T17 and T19). Those items were among those 
mentioned in the schedule of evidence and additional forms BI256A. At the hearing the claimant handed in the documents now at pages 45 to 49 of the papers before me, which included a report dated 22 November 1990 by Mr Jowett. At the hearing, the claimant was represented by Mr T. Searle of the Transport and General Workers Union, who made submissions to the MAT. The claimant gave evidence and also, it appears, was medically examined. The written observations on behalf of the Secretary of State (now at pages T11 and T12) did not-include a submission that the AMA's assessment was correct or reasonable, but asked the MAT to "re-consider and decide an appropriate assessment". The Secretary of State's representative was recorded by the MAT chairman as having made an open submission, which would have been to the same effect, at the hearing.
     
The medical appeal tribunal's decision
     
      4.    The MAT confirmed the AMA's decision and made an assessment of 12% disablement from 20 May 1990 for life, after offsetting 3% for pre-existing osteo-arthritis. The sole recorded finding of fact is "We adopt the clinical.findings of the Adjudicating Medical Authority dated 15.5.91". The recorded reasons for decision were:
     
      "We heard the claimant and his representative. We considered all the scheduled evidence. We examined the claimant. In the light of an examination and the report of Mr Jowell dated 17.8.91 where he refers to widespread arthritis at operation, we uphold the decision of the Board of 15.5.91."
     
Subsequent proceedings
     
      5.    The claimant applied on 13 February 1992 for leave to appeal to the Commissioner, which was granted by the MAT chairman on 22 December 1992.     The  grounds   put  forward      (see pages T27 and T41) were, in brief, that the medical evidence did not support the conclusion that the claimant had arthritis in the right knee before the accident on 5 February 1990 and that at the hearing the Secretary of State's representative was prepared to concede and to withdraw the support of the 3% offset in favour of an assessment of 15%. The claimant enclosed a report of an X-ray on 9 February 1990 and later sent in a copy of a letter dated 20 January 1991 [probably 19921 from Mr Jowell to the claimant's solicitor.
     
      6.    The submission on behalf of the Secretary of State, dated 23 February 1993, was that the MAT's decision was erroneous in point of law "for the reasons given by the claimant in his grounds of appeal". The submission was that there was no evidence in the papers to show that the claimant suffered from osteo-arthritis before the accident and that the MAT should not have made any offset as the osteo-arthritis was not causing any disability at the time of the relevant accident. In addition, the reasons for decision were possibly too brief to enable the claimant to understand why the MAT reached its decision and the MAT did not record what it found the relevant loss of faculty to be.
     
      7. In the light of that submission the claimant's representative withdrew the previous request for an oral hearing of the appeal. Since I did not find the written submissions on behalf of either the claimant or the Secretary of State persuasive I directed that there should be an oral hearing. That direction also indicated that at the oral hearing I wished to hear argument
     
      "as to whether the submission by the Secretary of State's representative (in paragraph 8 of the document dated 23 February 1993) that "the Medical Appeal Tribunal should not have made any offset as the osteo-arthritis was not causing any disability at the time of the relevant accident" is legally correct. In so far as that submission was based on paragraph 11 of Commissioner's decision R(I) 1/81, I wish to hear argument as to whether that interpretation of paragraph 11 of R(I) 1/81 is consistent with the terms of regulation 11(2) and (3) of the Social Security (General Benefit) Regulations 1982 and with earlier Commissioner's decisions such as R(I) 2/74 (in particular,    paragraphs 24 and 25),  R(I) 8/74 (in particular, paragraph 6), R(I) 13/75 (in particular, paragraphs 19 and 20) and R(I) 3/76."
     
      8.    The oral hearing took place on 25 April 1994. The claimant attended and was represented by Mr L.J. Wilson of the Transport and General Workers Union. The Secretary of State was represented by Ms C. Harold of the Office of the Solicitor to the Department of Social Security. Mr Wilson submitted that there was no evidence on which the MAT could have based its conclusion that the claimant was suffering from osteo-arthritis in the right knee before the accident of 5 February 1990, or, in the alternative, that the MAT gave no reasons for picking out the elements of. the evidence which supported its conclusion and ignoring others, especially within the report of Mr Jowett. On the Commissioner's decisions referred to in my direction, he submitted that paragraph 11 of R(I) 1/81 should be applied in the present case, so that the MAT had erred in law in not pointing to anything which the claimant could not do prior to the accident of 5 February 1990. In relation to the earlier decisions, he submitted that the MAT did not make any finding that the claimant would have suffered any disablement if he had not had the industrial accident. Ms Harold submitted that the MAT had failed to record any findings about the disabilities which the claimant would suffer or to record the findings of its medical examination of the claimant, and had so failed to come up to the standard required in the guidelines set out by Neill LJ in Evans and others v Secretary of State for Social Security (30 July 1993). Ms Harold was reluctant to make any submission on the question of the correctness of paragraph 11 of R(I) 1/81, but after some prompting submitted that it was ambiguous and should not be interpreted so as to restrict the circumstances in which an offset could be imposed under regulation 11(3) of the Social 3 Security (General Benefit) Regulations 1982 to those in which a pre-existing condition was causing some disability at the date of the industrial accident.  

Was the medical appeal tribunal's decision erroneous in point of 0f law?
     
      9.    I have concluded that it was, but before explaining why I must deal with the submissions put forward on behalf of the claimant.
     
      10. The first point put forward in the claimant's written submissions was that it was contrary to the principles of natural justice for the MAT to have made the offset of 3% when the Secretary of State's representative had conceded that the assessment should be made without the offset. It is not clear that the Secretary of State's representative in fact went further than the neutral position of an open submission, raising the issue of whether there should have been an offset or not. However, I am prepared to assume that the Secretary of State's representative in fact conceded that 15% was the proper assessment. On that basis, there was no breach of the principles of natural justice in the application of the offset. A medical appeal tribunal is an inquisitorial body. Its duty is to apply its expert medical judgment to the evidence before it and to apply the relevant legislation to the facts as it finds them. In carrying out that duty it is not bound to accept any concession made by one party to the proceedings or any agreement on particular issues between parties. Those principles have been stated and re-stated many times. I adopt in the context of medical appeal tribunals what was said about social security appeal tribunals in Commissioner's decision CIS/360/1991, to be reported as R(IS) 5/93. The Commissioner held that such tribunals' "investigatory function has as its object the ascertainment of the truth and is not restricted as in ordinary litigation where there are proceedings between parties, to accepting or rejecting the respective contentions of the claimant on the one hand and of the adjudication officer on the other". There was no suggestion that the claimant or his representative failed, in reliance on the concession by the Secretary of State's representative, to put forward evidence or submissions which they otherwise would have done. There might be circumstances in which, if a medical appeal tribunal were minded not to accept some matter which was agreed between the parties, it would be necessary to indicate that to the parties and give them an opportunity to make submissions or produce evidence on that matter. But that would only be the case where in effect some point emerged that the claimant could not reasonably be expected to have considered (compare the approach in R(I) 2/91 to prescribed disease cases where the unchallenged diagnosis question is referred to a medical appeal tribunal along with an appeal on the assessment of disablement and the medical appeal tribunal considers that the diagnosis is wrong). In the present case the 3% offset was the very issue under challenge in the claimant's appeal. He therefore had adequate opportunity to prepare submissions and evidence on the issue for the MAT hearing  on 29 November 1991. There was no breach of the principles of natural justice.
     
      11. The claimant also challenged the MAT's conclusion that he had arthritis at the date of the accident. In so far as that point relied on evidence not presented to the MAT of 29 November 1991 it cannot demonstrate any errors of law. A medical appeal tribunal cannot be faulted for failing to take account of evidence which was not before it. In so far as the claimant seeks to show that the MAT's conclusion on the medical matters before it was wrong, he cannot demonstrate any errors of law either. The assessment of evidence on medical matters is something for the expert judgment of the highly qualified members of a medical appeal tribunal, and Commissioners have no power, even if they had the knowledge, to interfere in such medical judgments. However, the claimant's grounds of appeal, as elaborated at the oral hearing, can be interpreted as putting forward the argument that there was no evidence that he suffered from arthritis before the accident, as it was also put on behalf of the Secretary of State in the submission dated 23 February 1993. If a decision or conclusion is based on no evidence, that goes beyond expert medical judgment and becomes an error of law (see R(I) 14/75 and R(SB) 11/83). I cannot possibly accept that argument in the present case. In the comments dated 16 March 1993 (page 52) the claimant accepts that arthritis was found in the right knee during the operation on 28 November 1990. That is confirmed by the summary of the hospital case notes for that date. There was also the clinical finding of crepitus by the AMA. The question of whether that evidence, when weighed against the other evidence before the MAT, showed that there were arthritic changes in the right knee prior to the accident is pre-eminently one for the expert medical judgment of the MAT. Quite clearly there was some evidence to that effect. The MAT's assessment of the evidence is not a matter in which I can interfere.
     
      12. Where the claimant might have a stronger case to make is in relation to the reasons given by the MAT for its medical conclusion that there was pre-existing arthritis present in the right knee at the date of the industrial accident. At the oral hearing, Ms Harold submitted that the MAT had failed to come up to the standards required by the Evans case in that respect. I would have had great difficulty in accepting that submission, but fortunately I do not need to go into the matter. That is because there are other respects in which the MAT clearly failed to come up to the Evans standards, which on their own require its decision to be set aside as erroneous in point of law.
     
      13.  The first is that the MAT did not record the findings of the medical examination carried out by its members. The requirement to do so is expressly mentioned by Neill LJ at page 28 of the transcript of the Evans case. In the present case, the examination of the claimant was specifically mentioned by the MAT in support of its conclusion, but no findings were recorded. The mere use of the printed words in box 2 of the form MAT3 (II) Dis adopting the clinical findings of the AMA is not sufficient.

      That does not tell the parties whether those findings are being adopted for want of anything better or because the MAT's own findings on examination are in accord with them. The second is that the MAT did not make the necessary findings as to the disabilities which the claimant would have suffered during the period over which disablement was assessed even if he had not suffered the industrial accident. Thus the necessary basis for the making of the offset was not established. I go into much more detail below about what must be established in order to justify an offset. A third failing is that the MAT failed to record that it had considered the evidence handed in at the hearing or what its view was of that evidence. For those reasons the MAT's decision did not comply with regulation 31(4) of the Social Security (Adjudication) Regulations 1986 and must be set aside. Accordingly, by virtue of section 48(5) of the Social Security Administration Act, I must refer the appeal to a completely differently constituted medical appeal tribunal for determination, in accordance with the directions given below.
     
Directions to the new medical appeal tribunal
     
      14. There must be a complete rehearing before the new appeal tribunal, at which all issues of fact and medical judgment will be open on the evidence presented and the submissions made to the new appeal tribunal. A different view might be taken, for instance, of the appropriate gross percentage of disablement or of the period for which an assessment should be made in the light of the further medical reports already submitted on behalf of the claimant or of the new appeal tribunal's own medical examination. The new appeal tribunal must make all the necessary findings of fact. In particular, it must decide whether the osteo-arthritis in the claimant's right knee was contracted before or after 5 February 1990. If it decides that it was contracted after 5 February 1990, it must decide whether it was a consequence of the injury received in the industrial accident, in which case it forms part of the resulting loss of faculty, or not. The disabilities resulting from whatever is included within the relevant loss of faculty must then be assessed in accordance with paragraph 1 of Schedule 8 to the Social Security Act 1975 (re-enacted in Schedule 6 to the Social Security Contributions and Benefits Act 1992). However, where either some disability also results from a cause other than the industrial accident (as might be the case where the osteo-arthritis was not part of the loss of faculty) or some disability might have been expected to have resulted if the industrial accident had not happened (as might be the case even though the osteo-arthritis was part of the loss of faculty), regulation 11 of the Social Security (General Benefit) Regulations must be applied. That follows from regulation 11(2) (made under the power given in paragraph 1(b) of Schedule 8), which provides:
     
      "(2) where the extent of disablement is being assessed for the purposes of section 57 (of the Social Security Act 19751, any disabilities which, though resulting from the relevant loss of faculty, also result, or without the relevant accident might have been expected to result, from a cause other than the relevant accident (hereafter in this regulation referred to "the other effective cause") shall only be taken into account subject to and in accordance with the following provisions of this regulation."
     
      In the circumstances presently under discussion the relevant provision would be regulation 11(4). I need give no more directions in relation to that provision. If the new appeal tribunal decides that the osteo-arthritis was contracted before 5 February 1990 then it necessarily cannot form part of the loss of faculty, but regulation 11(2) will come into play where some disability resulting from the loss of faculty might have been expected to result from the osteo-arthritis if the industrial accident had never happened.  In that case, regulation 11(3) would be the relevant provision. I give detailed directions below on the interpretation of that provision.
     
      15.  As noted in paragraph 8 above, at the oral hearing Ms Harold did not maintain the view of regulation 11(3) put forward on behalf of the Secretary of State in the written submission dated 23 February 1993. But Mr Wilson did submit that that view was correct. In my judgment that view is based on what is a common misunderstanding of the effect of a number of Commissioners, decisions. Therefore I shall attempt to set out relatively fully where the confusions have arisen and what is the correct approach.
     
      16.  The starting point must be the terms of regulation 11 of the Social Security  (General  Benefit)  Regulations 1982. Paragraph (3) provides:
     
      "(3) An assessment of the extent of disablement made by reference to any disability to which paragraph (2) applies, in a case where the other effective cause is a congenital defect or is an injury or disease received or contracted before the relevant accident, shall take account of all such disablement except to the extent to which the claimant would have been subject thereto during the period taken into account by the assessment if the relevant accident had not occurred."
     
      17.   Under paragraph (2) the disabilities caused by the relevant loss of faculty must also have another effective cause before paragraph (3) can operate. Then, by definition, some disability would have resulted from the other effective cause during the period taken into account by the assessment of disablement, or might have been expected to result. Paragraph (3) applies where the other effective cause arises before the relevant accident, but would result in disability in that period. It requires the adjudicating authority first to assess the disabilities resulting from the relevant loss of faculty and any other effective causes and then to deduct ("offset") an assessment of the disability which the claimant would have suffered in the period of assessment if the relevant accident had never happened. Thus the focus must be on the disabilities which would have been suffered in the period covered by the assessment of disablement on the hypothetical assumption that there had not been an industrial accident. It is quite possible that a condition which was causing no symptoms at the date of the relevant accident could cause disability during the period of assessment. Providing that the cause of that disability was a congenital defect or an injury or disease received or contracted before the relevant accident, and that the proper findings of fact are made, paragraph (3) then requires an offset. That is the natural, straightforward, reading of regulation 11(3). Do any Commissioner's" decision suggest anything to the contrary?
     
      18.  The proper approach was described very clearly indeed by the then Chief Commissioner in R(I) 2/74. In paragraph 24 of that decision he wrote:
     
      "The question for the tribunal was therefore not whether at the date of the accident [12 January 1971] the condition of the claimant's left foot was abnormal compared with that of a man of the same age etc. (Schedule 4 paragraph 1(a) [now paragraph 1(a) of Schedule 6 to the Social Security Contributions and Benefits Act 1992]), but whether during any period after 6th March 1972 [the date the assessment began] and to what extent the claimant would have been subject to disability in his foot if the relevant accident had not occurred. The question what was the condition of the claimant's foot before the accident no doubt was a preliminary question calling for an answer. But the final, vital, statutory question was to what extent, if the relevant accident had not occurred, the claimant would have been subject to disablement during the relevant assessment period after the accident. That vital question the tribunal never answered, as the record shows."
     
      That passage supplies the essential context to what the Chief Commissioner wrote in paragraph 25 of that decision, part of which is often quoted without being understood. He wrote:
     
      "No doubt there are cases where the answers may seem obvious. If a man has had his hand amputated before the relevant accident it goes without saying that he would have suffered from disability in that arm whether the subsequent relevant accident to that arm had happened or not. In some cases that disability has already been assessed. Even however if in such a case findings of fact on the various questions arising under the regulation may be unnecessary, in my judgment this was not such a case. The accident to the claimant's left foot at the age of 16 would have happened in 1929 or 1930. A pre-existing condition and a disability are different things: the one is positive and indicates what was there at the time of the accident: the other is usually negative and indicates that the claimant cannot do certain things owing to the relevant loss of faculty. I think that in this case the tribunal should have found the facts and recorded their reasons much more specifically in terms of the actual Act and regulation."

      It could not be plainer in context that the Chief Commissioner was requiring findings of fact both on the existence of a pre-existing condition and on the disabilities that would have resulted from that condition in the period of assessment even if the relevant accident had never happened. He was not requiring that a pre-existing condition must have been causing some disability prior to the relevant accident before there could be an offset.
     
      19.  Subsequent Commissioners' decisions emphasise that if there is merely a finding of fact on the existence of a pre-existing condition that does not justify an offset. There must also be a finding of fact on the disability which would have resulted in the period of assessment. That is again put very clearly in paragraph 6 of R(I) 8/74, where there had been a finding only that the claimant had a hysterical disposition, not on what disability she would have suffered if the industrial accident had never happened. The statement in paragraph 20 of R(I) 13/75 that the regulation "does not authorize an offset in respect of a pre-existing personality defect; it only authorizes an offset for a disability" is simply a summary of the effect of R(I) 8/74. It does not carry the meaning that a disability must exist at the date of the relevant accident before an offset is authorised, nor does any other part of R(I) 13/75.    Similarly, in R(I) 3/76 the statement in paragraph 12(c) that an "offset is only authorised in respect of a disability, not in respect of a cause or a potential cause of a disability" is no more than a restatement of the same point as made in paragraph 20 of R(I) 13/75.
     
      20. However, it is possible that confusion began to creep in in paragraphs 17 and 18 of R(I) 3/76. The claimant there had hit her head on a filing cabinet incurring a detachment of the retina in her left eye. The effect was some loss of vision in that eye. She had previously suffered from myopia and the medical appeal tribunal made an offset of 5% from the gross assessment of 12% for life "in view of the high degree of probability of spontaneous retinal detachment in this case". Before the Commissioner it was submitted on behalf of the Secretary of State that the appeal tribunal had not made it clear whether or not it "regarded myopia as a pre-existing condition amounting to a disability and hence the other effective cause". The Commissioner said this:
     
      "17. I have come to the conclusion that I should accept the Secretary of State's submission but for a reason somewhat different from that advanced on her behalf. It is there suggested that the tribunal might have regarded "myopia as a pre-existing condition amounting to a disability". I am uncertain what this means. If "myopia" is used to describe the underlying condition causing the claimant to be short-sighted, then I think that it corresponds with the expression "loss of faculty" used in the Act and regulations. On the other hand, if "myopia" is used to describe the short-sightedness from which the claimant suffered before her accident, then it was a disability.

      Possibly the submission proceeds from the point of view that "loss of faculty" and "disability" express overlapping concepts. It has been said that the concepts underlying these expressions may overlap, but the statute envisages them as separate: see the speech of Lord Simon of Glaisdale in Jones v Secretary of State for Social Services. Hudson v Same [1972] A.C. 944 at p. 1019G (also the Supplement to the Commissioner's reported decision R(I) 3/69 at p. 214D). Accordingly, it is wise, if possible, to keep them separate. I do not see how the underlying condition can amount to a disability. In my view it is a cause of one or more disabilities, but not itself a disability.
     
      18. On the other hand I do not think that the medical appeal tribunal have succeeded in making their reasons for the offset clear. It is out of the question that they overlooked the legal principle that an offset is authorised only for a disability, because they discussed that very point with the Secretary of State's representative. Yet they have not explained how, in their view, the "high degree of probability of spontaneous retinal detachment" can constitute a disability. I consider that by using this phrase without explanation they have failed to give their reasons as required by [the regulations]."
     
      21. I must confess that I find it very difficult to extract a clear principle from those paragraphs. With respect to the learned Commissioner, it appears that he allowed himself to be sidetracked by the terms of the Secretary of State's submission to him. It is quite easy to see how his words have been interpreted as requiring that for an offset to be authorised under regulation 11(3) the "other effective cause" must have been causing some disability at the date of the industrial accident. In view of the very clear exposition in the earlier Commissioners' decisions, I consider that the Commissioner must have been taking it as read that an offset was required whenever the other effective cause, in the form of the myopia which was either a congenital defect or a disease contracted before the industrial accident, would have caused disability in the period of assessment. The problem in R(I) 3/76, as I see it, was that if there had been a spontaneous detachment of the retina that would have caused exactly the same degree of disablement as caused by the industrial accident, yet the appeal tribunal only applied an offset of 5% from the gross assessment of 12%. It did not conclude (as apparently put to the appeal tribunal by the Secretary of State's representative: paragraph 9) that spontaneous retinal detachment would probably have occurred by a certain date even if the industrial accident had not happened, so that from that date there was no remaining loss of faculty due to the industrial accident, or the disablement resulting from the loss of faculty was nil. That suggests that the appeal tribunal made some kind of assessment of the probabilities of spontaneous retinal detachment occurring and adjusted the assessment of disablement accordingly. That is not a permissible method of reasoning within the terms of regulation 11(3). There can only 10 be an offset when the adjudicating authority is satisfied that a disability would have been present from the beginning of or from some date within the period of assessment, and then the amount of the offset must be equal to the assessment of the extent of that disablement. Alternatively, the appeal tribunal could have taken the view that the claimant would have suffered from some loss of full visual acuity in the period of assessment regardless of the industrial accident and of whether a spontaneous detachment of the retina occurred, in the form of the short-sightedness resulting from the underlying condition of myopia. It could then have properly determined that an offset was required from the beginning of the period of assessment. But the appeal tribunal did not make the findings of fact necessary to form a basis for such a conclusion; indeed its reference to the high degree of probability of spontaneous retinal detachment points against that conclusion. The appeal tribunal had failed to make clear the link between the pre-existing condition and the disability which it considered the claimant would have suffered as a result in the period of assessment. I consider that that fault is what the Commissioner was pointing out in paragraph 18 of R(I) 3/76.
     
      22. The facts of R(I) 3/76 were rather unusual. There was a risk of spontaneous retinal detachment independent of the industrial accident. The spontaneous detachment would either have happened on some date or other or not happened at all. If it had happened, then from that date the claimant's disability would have been identical to that caused by the industrial accident. Such "chance" cases, where the industrial accident has precipitated a specific risk which may or may not have been precipitated otherwise, form a special category where a partial offset throughout the period of assessment, rather than a limitation in time of the full assessment, may not be appropriate. The ordinary case is not like that. An example would be where a claimant sustains a back injury and the adjudicating authority is satisfied that an assessment of disablement for life is appropriate. However, it is also satisfied that pre-existing arthritic changes in the spine, causing no symptoms at the date of the injury, would have caused symptoms by some date in the future, although the speed of progression of the disease to the stage of causing symptoms, and the severity of the symptoms, cannot be predicted precisely. In such circumstances, I consider that the adjudicating authority may make a uniform offset over the whole period of the life assessment, having taken an overall view of the whole period, and it is not an obstacle that the claimant would not have been suffering any disability at the beginning of the period of assessment in the absence of the industrial accident. But the adjudicating authority may also, depending on the circumstances, including what is predicted for the future, make a stepped assessment, applying no offset initially, but bringing one in at some future date, or applying different levels of offset for different parts of the period of assessment.
     
      23. The final Commissioner's decision which I must consider, R(I) 1/81, may also have been a "chance" case. The claimant  suffered a blow on the head in an industrial accident which precipitated the condition of multiple sclerosis. The medical appeal tribunal found that "the constitutional liability to develop the condition must have been present prior to the relevant accident and we regard this as a positive pre-existing disability". The appeal tribunal made an offset of 10% from its assessment of 15% for life. It may have been the case that without the industrial accident there was a risk that the claimant would develop multiple sclerosis, in which-case the resulting disability would have been of the same extent as that resulting from the industrial accident, but that she might not have developed the disease at all. However, the terms in which the Commissioner defines the appeal tribunal's error cannot be restricted to "chance" cases. He said in paragraphs 11 and 12 of the decision:
     
      "11. The Tribunal     asserted    that   the claimant's constitutional liability to develop multiple sclerosis was a 'positive pre-existing disability'. I think that they devised this phrase after reading paragraph 25 of the Commissioner's reported Decision R(I) 2/74. The relevant passage is not authority for their finding. On the contrary, it contradicts the finding. The author (the then Chief Commissioner) wrote:­
     
      'A pre-existing condition and a disability are different things: the one is positive and indicates what was there at the time of the accident: the other is negative and indicates that the claimant cannot do certain things owing to the relevant loss of faculty ... '
     
      In their Decision the Tribunal did not point to anything which the claimant could not do prior to her accident. There was no evidence enabling them to do so. In my view, the constitutional liability to develop the disease cannot have been a 'disability' because it was wholly symptomless. Such liability corresponds with the concept of 'loss of faculty', that is to say it is a potential cause of disability but not itself a disability.
     
      12. Accordingly, the error of law which the Secretary of State admitted consists in the failure by the Tribunal to apply correctly regulation 2(2) and (3) of the Benefit Regulations [re-enacted as regulation 11(2) and (3) of the Social Security (General Benefit) Regulations 19821. In particular, they confused a 'disability' with a 'loss of faculty', and they made an unauthorised offset, that is to say an offset for something which was not a 'disability'."
     
      24. The plain meaning of those words, which appear to be directed to the general law on the assessment of disablement, is that in order for an offset for a disability to be authorised under regulation 11(3), it must be possible to point to symptoms suffered and things which the claimant could not do prior to the 12 industrial accident. I am unable to accept that as an accurate description of the law. It is inconsistent with the words of regulation 11, which must remain the fundamental authority, rather than any explanation or gloss supplied by the Commissioner. It is also inconsistent with the statements of the effect of the law in R(I) 2/74, R(I) 8/74 and R(I) 13/75, the last two of those decisions having been given by the same Commissioner who gave R(I) 3/76 and R(I) 1/81. Since the learned Commissioner in R(I) 1/81 considered that he was merely expounding what had been stated in many other Commissioners' decisions in the preceding 10 years (see paragraph 13 of his decision) I have relatively few qualms in preferring the statement of the law summarised in paragraphs 18 and 19 above and in holding that paragraphs 11 and 12 of R(I) 1/81 should not be followed. I direct the new appeal tribunal to apply that approach and the plain words of regulation 11(3) if it finds that the claimant contracted osteo-arthritis in the right knee before 5 February 1990.
     
      25. I note that the author of Rowland, Medical and Disability Appeal Tribunals: the Legislation (1993 edition), in his comments on regulation 11, after mentioning the Commissioners' decisions cited above, says:      
     
 "An adjudicating medical authority might legitimately apply an offset if a pre-existing, and previously symptomless, condition could have been expected to produce disability at some time even if the accident had not occurred."

I endorse his immediately following comment that:
     
      "such reasoning must be clear, and a medical appeal tribunal which fails to record good reasons for applying an offset in a case where a claimant had asserted that he or she had no symptoms before the relevant accident is liable to find its decision set aside on appeal."
     
      It cannot be emphasised too firmly that an offset cannot be justified merely by a finding that a claimant had some predisposition or liability to develop some disabling condition. there must be a finding that the claimant would have suffered a disability due to the other effective cause even if the industrial accident had never happened.
     
      26. It must also be emphasised that the fact that the claimant has succeeded in this appeal to the Commissioner carries no implication one way or the other as to what the proper assessment of disablement should be in his case.

 (Signed) J Mesher Commissioner
     
      						Date:      19 May 1994