R v Niguidula

Expert evidence

1. Section 79(1) of the Evidence Act, provides: 79 Exception: opinions based on specialised knowledge (1) If a person has specialised knowledge based on the person's training, study or experience, the opinion rule does not apply to evidence of an opinion of that person that is wholly or substantially based on that knowledge.
2. The specialised knowledge upon which the opinion is said to be wholly or substantially based relates to "differentiating self-inflicted from inflicted sharp force injuries".
3. In Honeysett v The Queen (2014) 253 CLR 122; [2014] HCA 29 the Court stated (at [23]): "23 … "'Specialised knowledge' is to be distinguished from matters of 'common knowledge'. Specialised knowledge is knowledge which is outside that of persons who have not by training, study or experience acquired an understanding of the subject matter. It may be of matters that are not of a scientific or technical kind and a person without any formal qualifications may acquire specialised knowledge by experience. However, the person's training, study or experience must result in the acquisition of knowledge. The Macquarie dictionary defines 'knowledge' as 'acquaintance with facts, truths, or principles, as from study or investigation' (emphasis added) and it is in this sense that it is used in s 79(1). The concept is captured in Blackman J's formulation in Daubert v Merrell Dow Pharmaceuticals Inc; 'the word 'knowledge' connotes more than subjective belief or unsupported speculation. [It] applies to any body of known facts or to any body of ideas inferred from such facts or accepted as truths on good grounds.'" [footnotes omitted]
4. In R v Warwick (No.37) [2019] NSWSC 196 Garling J said (at [8]) (referring to Honeysett): "The Court noted in [24] that it will sometimes be difficult to separate observations and knowledge of everyday affairs and events, from the body of specialised knowledge on which an expert's opinion depends. Therefore, it is sufficient that the expert opinion is "substantially" based on specialised knowledge which is based on training, study or experience."
5. The plurality in Dasreef Pty Ltd v Hawchar (2011) 243 CLR 588; [2011] HCA 21 noted uncontroversially (at [32]): "To be admissible under s 79(1) the evidence that is tendered must satisfy two criteria. The first is that the witness who gives the evidence 'has specialised knowledge based on the person's training, study or experience'; the second is that the opinion expressed in evidence by the witness 'is wholly or substantially based on that knowledge'."
6. Their Honours later observed (at [37]): "It should be unnecessary, but it is nonetheless important, to emphasise that what was said by Gleeson CJ in HG [v The Queen (1999) 197 CLR 414; [1999] HCA 2) (and later by Heydon JA in the Court of Appeal in Makita (Australia) Pty Ltd v Sprowles [(2001) 52 NSWLR 705; [2001] NSWCA 305] is to be read with one basic proposition at the forefront of consideration. The admissibility of opinion evidence is to be determined by application of the requirements of the Evidence Act rather than by any attempt to parse and analyse particular statements in decided cases divorced from the context in which those statements were made. Accepting that to be so, it remains useful to record that it is ordinarily the case, as Heydon JA said in Makita [(2001) 52 NSWLR 705 at 744 [85], that "the expert's evidence must explain how the field of 'specialised knowledge' in which the witness is expert by reason of 'training, study or experience', and on which the opinion is 'wholly or substantially based', applies to the facts assumed or observed so as to produce the opinion propounded."

The report

1. In his report, Professor Duflou sets out his training study and experience, his acceptance of the code of conduct, his understanding of the purpose of the report, and the material he received. He notes that he had not previously been involved in the investigation of this matter, nor personally examined the deceased at any time. Professor Duflou sets out his understanding of the circumstances in which the deceased was found, a summary of the autopsy report, a description of the knife that was found, and describes, from the photos supplied to him, the T-shirt the deceased was apparently wearing at the time he was stabbed.
2. In his summary of the autopsy relied on by him, Professor Duflou says: [2] "Dr Irvine describes a perimortem stab wound on the front of the chest, and multiple superficial abrasions and bruises many of which appeared to have been sustained some time prior to death. The stab wound had the following characteristics: There was a 2.3 cm diagonally aligned stab wound on the left anterior chest wall, with a 1 mm squaring off/blunting of the medial aspect. There were no marks on the skin surrounding the stab wound. The track of the wound passed from front to back, downwards and to the right for a distance of about 7 cm, passing between ribs 1 and 2 on the left, through the pericardium, through the pulmonary trunk and ending in the right atrial appendage of the heart."
3. Later in the report, Professor Duflou notes that there were no hesitation marks or defence injuries. [3]
4. In the critical section of his report, titled "differentiating self-inflicted from inflicted sharp force injuries", [4] Professor Duflou expresses the opinion that "most forensic pathologists have training and experience in this area, and it is my experience that most forensic pathologist[s] are able to comment on whether a wound may be self-inflicted or not." [5] While he does not explicitly include himself in this category, in context, he does so implicitly.
5. Professor Duflou observes that there is "generally no single way of determining whether a wound has been self-inflicted or has been inflicted by an assailant". [6] He notes the exception where an injury has been sustained to an area of the body the person would not themselves have been able to access. I pause to note that whether a person could or could not access an area is likely to be specific to the individual. Further, the conclusion that the wound was not self-inflicted on the basis that the person could not access that area themselves, would not appear to require expert evidence. This observation, to an extent, reflects the accused's complaint with respect to Professor Duflou's conclusion, a matter to which I will return.
6. Professor Duflou makes the following general observations: [7] 1. "[s]elf-harm by sharp force is not uncommonly seen in forensic pathology practice, although the types of injuries sustained are more commonly in the form incised wounds, or slashes, rather than penetrating stab wounds"; and 2. he has "seen self-inflicted stab wounds on multiple occasions, many of which have had unusual or atypical features".
7. The above observations at the least, leave open self-infliction as a possibility with respect to the present case.
8. Professor Duflou observes that there are various means of assessing a wound which can give indications as to how it was sustained. Professor Duflou then sets out a table (taken from a publication co-authored by Professor Duflou) which he says provides "one such approach to ascertain whether injuries sustained were the result of self-infliction or as a result of infliction by an assailant". [8] The table is reproduced below: [9] [33A.2020] Self-inflicted injuries mimicking an assault The principal features of the imitative assault and genuine assault are compared: Characteristics of imitative and genuine assault injuries Imitative assault Genuine assault Localisation Possibly confined to one side of the body If multiple, confinement to one side of body unusual Multiple injuries clustered together If multiple, generally more widespread Sensitive areas (eg, eyes, mouth) are avoided Sensitive areas are included in the more random distribution Usually at sites of access by the individual Can be at sites inaccessible by the individual Injury type All injuries may be of a single type If multiple injuries, often a mixture of types Injuries may suggest a single causative agent Mixture of injuries can be associated with a range of causative agents Bruises and lacerations are rare Bruises and lacerations are common Injury severity Of similar severity If multiple, injuries usually vary in severity Other No defence injuries Defence injuries are common

1. No specific comment is made by Professor Duflou with respect to the table or its application to the deceased. My own observation is that the table alone does not appear to allow any conclusions to be drawn in the present case. With respect to the presence of "bruises and lacerations", I note that the deceased was described as having multiple "superficial abrasions and bruises", [10] however, it is then indicated in Professor Duflou's summary that "many [of these] appeared to have been sustained some time prior to death". [11] It is not clear whether there were any bruises or lacerations sustained that can be substantiated as having occurred around the same time as the fatal wound. Otherwise, the avoidance (if that accurately describes a case involving a single wound) of sensitive areas and the absence of defence injuries are factors in the column of matters characteristic of self-infliction.
2. Having set out the above table without comment, Professor Duflou, sets out of the following statistics provided by research in this area: [12] 1. "stab wounds to the chest are seen in 36% of self-inflicted cases versus 54% of homicidal cases" (I note there is no explanation of the remaining 10% of cases); 2. "there was no significant difference … in the number of wounds" as between self-inflicted cases and homicidal cases, (I add, making it a neutral factor); 3. "clothing was penetrated by the weapon in roughly equal percentages" (again making this a neutral factor); 4. "hesitation marks were seen in just under half of self-infliction cases"; and 5. "'defence wounds' were present in 37% of homicides".
3. Again, no specific comment is made by Professor Duflou with respect to the above statistics. My own observation is that the fact the wound was to the chest points to homicide over self-infliction, such wounds being more common in homicide than self-infliction. While not explicitly stated, I interpolate that hesitation marks are, at least, less common in cases of homicide. On this assumption, the absence of hesitation marks does not support self-infliction, however, nor does it, on the statistical information available, provide strong support for homicide. The extent of any support is likely a matter for a mathematician appraised of more information.
4. Professor Duflou then sets out the following observations based on his own experience: [13] 1. "intentional self-inflicted stab wounds to the chest are relatively uncommon" but he has seen multiple such cases; 2. hesitation wounds are "commonly seen in self-inflicted stab wounds" and uncommonly seen in wounds inflicted by an assailant; 3. "single self-inflicted stab wounds to the chest uncommonly pass through clothing, while such wounds [inflicted by the assailant] very commonly pass through the clothing should the person be wearing a shirt at the time"; and 4. "[l]ess commonly, the knife is left embedded in the lethal injury in [a case of] self-inflicted injury, while … a knife is almost never left in place in the wound in a person who has sustained an inflicted injury."
5. It might be noted that the above factors point to a conclusion that the wound was not self-inflicted. Some observations might be made. The first point can be compared with the statistics previously referred to above which provided a figure of 36% of stabbings to the chest as being self-inflicted, while 54% were by an assailant. The second point can be compared with the statistics which indicate hesitation marks in "just under half" of self-infliction cases. The third point can be compared with the statistics which suggest the penetration of clothing is a neutral factor. Professor Duflou's experience is not necessarily inconsistent with that statistic as he is speaking of a single stab wound through clothing while the statistics are not specific as to this. But the comparison of Professor Duflou's observation with the statistics highlights the difficulty in knowing what weight can be given to this factor in the absence of any understanding of the sample size Professor Duflou is drawing on. The fourth point similarly provides little assistance given it is not known how uncommon is for a knife to left in place in the wound. If it is rare, as Professor Duflou's language suggests, the factor is largely neutral.
6. Professor Duflou then concludes: [14] "23. In this case, there was a single stab wound on the left anterior chest wall which had passed through clothing. The track of the wound passed from front to back, downwards and to the right for a distance of about 7 cm, causing lethal injury to structures within the chest. I am unable to state whether the knife was used by a right handed or left handed person. There were no hesitation stab wounds, defensive injuries, or any other sharp force injuries sustained contemporaneously. The knife was not left embedded in the deceased's body. 24. Based on the above observations and analysis, it is my opinion that it is much more likely that the stab wound to the chest was the result of stabbing by an assailant rather than the result of being the result of self-infliction by the deceased."
7. With respect to Professor Duflou, it is not clear how he reasons from the table, the statistics and his own experience to the finding that it is "much more likely" that the wound was inflicted by assailant. I accept that he refers to factors which point towards such a conclusion. However, at [23] he also refers to the absence of defensive injuries which is a factor in favour of self-infliction. The significance of this has obviously been discounted in the process of reaching the conclusion. However, there is no articulation of why. In short, there is no analysis of the weight to be given to the various factors and their interaction. The report does not explain how the conclusion has been reached by any process of reasoning "substantially" based on Professor Duflou's specialised knowledge. Insofar as he relies on particular factors, it is not clear whether he is applying his expertise or is engaged in a more complex version of logic, such as the one referred to above, that is, a wound in a location unable to be reached by the victim is highly likely to be the result of an assailant.
8. Admissibility of the relevant paragraph of Professor Duflou's report is dependent upon my satisfaction that the opinion is substantially based on his specialised knowledge. I am not satisfied on the balance of probabilities that this is so: Evidence Act, s 142. That paragraph of the report is not admissible.
9. Having regard to my conclusion above, it is not necessary to consider the application of s 137 to this evidence. I note, however, that even if I were to accept the opinion as substantially based on Professor Duflou's specialised knowledge, I would have grave reservations in allowing it before the jury. Firstly, insofar as it is a conclusion drawn from various factors it will be necessary for the jury themselves to consider and understand those factors. The conclusion presented by a person with the authority of a highly qualified expert carries the risk that the jury (inevitably faced with a number of difficult issues to consider) will simply accept the conclusion without applying their own critical analysis. This concern is to be seen in the context of a conclusion expressed in the imprecise terms of "much more likely". To give meaning to the expression, it is necessary to understand the individual factors. It is therefore preferable that the jury themselves understand those individual factors.
10. I uphold the objection to paragraph [24] of the report of Professor Duflou of 13 April 2023.

Endnotes

1. Exhibit VD-B, [24]
2. Exhibit VD-B, [10]
3. Exhibit VD-B, [21], [23]
4. Exhibit VD-B, [20]
5. Exhibit VD-B, [20]
6. Exhibit VD-B, [20]
7. Exhibit VD-B, [20]
8. Exhibit VD-B, [20]
9. Duflou J, Ong B, Baber J, Burke M, Ranson D, Cordner S. Forensic pathology. In Freckleton I & Selby H (eds), 2017, Expert Evidence, Thompson Reuters.
10. Exhibit VD-B, [10]
11. Exhibit VD-B, [10]
12. Exhibit VD-B, [21]
13. Exhibit VD-B, [22]
14. Exhibit VD-B, [23]-[24]

Amendments 09 June 2023 - Restriction status uplifted DISCLAIMER - Every effort has been made to comply with suppression orders or statutory provisions prohibiting publication that may apply to this judgment or decision. The onus remains on any person using material in the judgment or decision to ensure that the intended use of that material does not breach any such order or provision. Further enquiries may be directed to the Registry of the Court or Tribunal in which it was generated. Decision last updated: 09 June 2023