HKSAR v. CHAN YIU SHING AND OTHERS

(Ruling 8)

HCCC 41/2016

[2018] HKCFI 312

IN THE HIGH COURT OF THE

HONG KONG SPECIAL ADMINISTRATIVE REGION

COURT OF FIRST INSTANCE

CRIMINAL CASE NO 41 OF 2016

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REASONS FOR RULING ON THE ADMISSIBILITY OF EXPERT EVIDENCE

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1.  In this trial the prosecution will seek to adduce the expert evidence in relation to explosives from two police officers, namely, Superintendent of Police Adam Roberts (PW46) and Chief Inspector of Police Nastor Lai (PW47).

2.  Mr Douglas Kwok, for the 2^nd defendant, objected to the admissibility of the expert evidence.  I ruled against the objection and said I would give my reasons for doing so which I now do. 

3.  Mr Kwok argued that because “explosive substance” is defined under the Crimes Ordinance, Cap 200, any opinions the experts may give about a certain substance is an opinion of the law and therefore not admissible.

4.  Under section 52 of the Crimes Ordinance it is provided that “ “explosive substance” shall be deemed to include any materials for making any explosive substance; also any apparatus, machine, implement or materials used, or intended to be used, or adapted for causing, or aiding in causing, any explosion in or with any explosive substance; also any part of any such apparatus, machine or implement.”

5.  I had difficulty understanding the point that Mr Kwok was seeking to make.  The Ordinance provides a definition of an explosive substance which is inclusive and not exhaustive.  It is still a matter for the tribunal of fact when deciding whether a criminal offence has been committed under the offences of Part VII to be guided by the definition as provided.  It includes “any materials for making any explosive substance”.  As one would expect, it is in relation to the materials necessary for the making of an explosive substance that is addressed by the two experts in their reports.

6.  Mr Kwok’s main complaint as refined in oral submissions concerned PW46’s statement at paragraph 5.3.4 of his expert report where he stated:

“Both Aluminium powder and iron oxide are used in non-explosives related applications, for example, for paint pigments. I have discounted these applications in this case due to the context in which the exhibits were recovered.”

7.  Mr Kwok argued that PW46 by stating he discounted the non-explosive related applications was expressing an opinion outside his expertise, and further by this statement, he was seeking to address the ultimate issue in the case.

8.  First, it needs to be appreciated that PW46 in this paragraph was explaining what he had taken into account when forming the opinion that he expressed at paragraph 5.1 which was that a combination of the quantity of aluminium powder and iron oxide recovered at the ex-ATV building “could have produced approximately 390 gm of a thermite mixture, which is a pyrotechnic substance having the main effect of producing extreme heat”. 

9.  What PW46 stated in paragraph 5.3.4 was one of the matters he had taken into account when forming his opinion.  The nature and mixture of the substances and their application are, in any event, matters within PW46’s expertise. 

10.  Secondly, it may be viewed, that PW46 by this statement was not giving evidence in relation to the ultimate issue in the case, but even if he was, given the nature and context of this statement it is, in my view, permissible for him to do so. 

11.  It is now established that in the context of criminal proceedings, an expert can give his opinion on the ultimate issue provided that the judge makes it clear to the jury that they are not bound by the expert’s opinion, and that the issue is for them to decide.  See HKSAR v Chin Kam Chiu, CACC 179/2004, 22 July 2005, unreported, per Lugar-Mawson J, giving judgment of the Court, at paragraph 124, where the Court adopted and applied R v Stockwell (1993) 97 Cr App R 260. 

12.  The rule of evidence at common law that an expert witness should not give evidence in relation to what is termed “the ultimate issue” in a case, namely, any fact in issue, has weaken considerably over recent times.  This is primarily due to the fact that the boundaries between acceptable expert opinion and the opinion that addresses the ultimate issue has become blurred because of the increasing complexity of evidential matters or issues that need to be addressed by the evidence of expert opinion.  This sometimes involves expert opinion on the ultimate issue in order to address complicated scientific or forensic matters as well as compliance with requirements or standards as seen in cases addressing accounting practices or professional standards. 

13.  It was Lord Taylor in Stockwell who accepted that if there was a rule prohibiting experts from giving an opinion on an ultimate issue, “… it has long been more honoured in the breach than the observance”.[1]

14.  In Chin Kam Chiu,[2] the following passage from Stockwell was quoted with approval:

“The rationale behind the supposed prohibition is that the expert should not usurp the functions of the jury. But since counsel can bring the witness so close to opining on the ultimate issue that the inference as to his view is obvious, the rule can only be, as the authors of the last work referred to (Tristram & Hodkinson: Expert Evidence Law and Practice) say, a matter of form rather than substance.

In our view an expert is called to give his opinion and he should be allowed to do so.  It is, however, important that the judge should make clear to the jury that they are not bound by the expert’s opinion, and that the issue is for them to decide.”

15.  In light of recent authority, an expert witness is able to give his opinion on an ultimate issue in criminal proceedings, so long as that opinion is within the area of the expert witness’s expertise and the judge makes it clear to the jury that they are not bound by the expert’s opinion, and that the issue is for them to decide. 

16.  I should add, however, that this will depend on the particular circumstances of the case, but primarily on the nature and necessity of the expert evidence, and the nature and contentiousness of the ultimate issue concerned.  I should also reiterate that, a critical factor is that the opinion evidence is a matter within the field and knowledge of the expert.  As observed by Gleeson NPJ in Fu Kor Kuen Patrick v HKSAR (2012) 15 HKCFAR 524 at paragraph 51:

“The propensity of some expert witnesses to express opinions not wholly or substantially based on their specialized knowledge, but based upon inferences of fact outside their field of particular training or experience is well understood. The danger for the proper process of fact-finding at civil or criminal trials is obvious. … An opinion, resting upon transparent factual assumptions, based upon a branch of knowledge in which the witness is an expert, may be of legitimate assistance to a finder of fact. It is when the witness goes beyond those bounds and expresses a judgment on a matter outside his area of specialized knowledge that the danger arises.”

17.  Mindful of the relevant legal principles and for the foregoing reasons, I rejected the objection by Mr Kwok as to the admissibility of the expert evidence of PW46 and PW47.