Expert evidence
27 It was submitted for the appellant that there were errors by the primary judge in reaching an adverse view of the evidence given by Mr Johnston, and not accepting that evidence, particularly in the following respects:
(1) The primary judge was not justified in considering that Mr Johnston had belatedly tailored his opinion to challenge Senior Constable Bain's evidence as to the point of impact (Judgment [51]).
(2) The primary judge was not correct to say that the foundation of his opinion as to the point of impact was that the impact was a central impact (Judgment [53]).
(3) The primary judge was not correct to say that Mr Johnston's reasoning based on throw distance was circular (Judgment [55]).
28 I note that the primary judge also said (Judgment [69]) in relation to Mr Johnston that his demeanour was at times defensive, evasive and argumentative, and that he adopted a partisan approach to the preparation of the report which was admitted into evidence after he became aware of serious deficiencies in his original report.
29 It is not possible from the transcript to get a full impression of Mr Johnston's demeanour; but in my opinion, the content of the transcript amply supports these views of the primary judge. To take three examples:
(1) Mr Johnston's attempt (1 Black 503LM) to minimise the importance of his earlier serious mistake as to the direction of the curve.
(2) Mr Johnston's evasion (1 Black 518) of questions concerning the omission from his report of any explanation of the divergent skid-marks.
(3) Mr Johnston's attempts (1 Black 521) to maintain that the impact by the appellant on the car was a central impact.
30 In my opinion also, Mr Johnston's attempt (1 Black 534) to minimise the effect on the respondent's car of the impact of the appellant on the windscreen is damaging to his expertise. The question at lines 13 to 15, referring to absorption of energy from the pedestrian, was not aptly expressed; but in my opinion, an expert attempting to assist the court should have provided a response that was helpful and not misleading. It was correct to say there was no transfer of energy from the pedestrian to the motor vehicle: what there was, in terms of energy, was a transfer of energy from the motor vehicle to the pedestrian, resulting in a loss of kinetic energy in the motor vehicle corresponding with a slowing of the motor vehicle's speed. It would have been more helpful and relevant to analyse the matter in terms of the forces involved: when the car applied sufficient force to accelerate the appellant from being stationary to a speed in the order of 40 to 50 kilometres per hour, Newton's third law shows that the same force was applied in the opposite direction by the pedestrian onto the car. Accepting, as did Mr Johnston, that the appellant had about one-tenth of the mass of the car, this force would plainly be substantial. Since the major damage to the car was to the driver's side of the windscreen, it is reasonable to infer that very substantial force was applied to this part of the windscreen.
31 As regards the three matters raised by the appellant, there is, having regard to the matters I have just discussed, no substance in the first two of them. However, as regards the third of them, I accept the submission that Mr Johnston's argument based on throw distance was not circular, and did give some rational support to his view that the impact occurred at about the same time as the skidding commenced. However, the other matters to which I have referred gave adequate ground for placing little weight on the expertise of Mr Johnston; and the contrary evidence of Mr Keramidas (2 Blue 686-696) is to my mind persuasive.
32 Accordingly, in my opinion, the primary judge was correct to conclude that it was the impact with the appellant that initiated the divergence of the skid-marks, and accordingly that the impact occurred after the car had been skidding for about six metres.
33 As regards the visibility of the appellant, in my opinion the primary judge was plainly correct to hold that, by reason of the state of the street lighting, the appellant would not have been silhouetted or otherwise visible to the respondent until picked up by her headlights, by which time he was only about 25 to 35 metres away.