HKSAR v. KHAW KIM SUN

HCCC 389/2023

[2024] HKCFI 3536

IN THE HIGH COURT OF THE

HONG KONG SPECIAL ADMINISTRATIVE REGION

COURT OF FIRST INSTANCE

CRIMINAL CASE NO 389 OF 2023

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R E A S O N S    F O R    R U L I N G

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A.  Introduction

1.  The defence objects to the admissibility of two features of the evidence to be called by the prosecution. The first relates to a stopper which was found in the drawer of a filing cabinet in Dr Khaw’s house almost a year after the death of his wife and daughter. The second relates to the expert evidence which the prosecution proposes to call about the merits of the research which Dr Khaw was purporting to conduct. The defence also ask the court to take judicial notice of the use of carbon monoxide in the eradication of rats.

B.  The stopper

2.  Because it was not appreciated that the deflated yoga ball in the boot of the car had been the source of the carbon monoxide which had killed Dr Khaw’s wife and daughter, no-one noticed that the yoga ball did not have the stopper on it. When it was realised that the yoga ball could have been the source of the carbon monoxide, and a search was made in the car for the stopper, it was not found in the car. In his closing speech, counsel for the prosecution asked the jury to consider whether the stopper found in the drawer had been the stopper from the yoga ball found in the car. The judge did not refer to that suggestion in her summing-up.

3.  The Court of Final Appeal said that there was no evidence to connect the stopper found in the drawer with the yoga ball found in the car, and was of the opinion that the judge should have told the jury that. Its core reasoning in quashing the conviction is contained in para 60 of the joint judgment of Fok PJ and Lam PJ:

“Without such directions, there is a risk that the jury could have committed the error of heaping a false inference that the stopper in the drawer was the stopper of the yoga ball in question (which is no more than conjecture) upon another false inference that the stopper of the yoga ball was missing at the time of the incident (which is not an inference which can be drawn on the evidence). On such impermissible reasoning, a juror might have treated the discovery of the stopper in the appellant’s drawer as a very strong indication that he was the person who removed the stopper from the yoga ball in the [car].”

In these circumstances, the defence argue that no evidence should be given about the stopper found in the drawer, save to the extent that it was something which was shown to Dr Khaw when he was interviewed. The prosecution agree with that, as do I.

C.  Dr Khaw’s research

4.  The prosecution’s case is that Dr Khaw purported to conduct research on the effect of carbon monoxide on rabbits because he was planning to use carbon monoxide to kill his wife, and needed to have an innocent explanation for why he had ordered the carbon monoxide in the first place. In other words, the research was a sham, and was in truth only a cover for what he was planning to do. In support of that, the prosecution relied on expert evidence in the original trial to the effect that the research was of no value whatever. It is proposed to rely on that evidence again in the retrial. That is the evidence to which the defence now object. No objection was taken to this evidence in the original trial.

5.  The defence’s argument has a number of strands. The principal one is that the prosecution cannot prove that Dr Khaw’s research was of no value. If the prosecution cannot prove that on the evidence which it proposes to call, that evidence becomes irrelevant. Three reasons are advanced for that. First, it is said that not one of the experts called by the prosecution testified to the effect that they thought that Dr Khaw’s research was a sham. In my opinion, that is beside the point. Whether Dr Khaw’s research was a sham was not something within the experts’ area of expertise. All that the experts could do was to express a view about the value of the research. Whether that research was a sham went to Dr Khaw’s reason for conducting research which the prosecution say was of no value. What his motive for doing the research was not something which the experts could have commented on. If they were asked to do that in the first trial, they should not have been. What they could have been asked, in addition to their own view about the research, was whether in their opinion any scientist could have regarded the research as of any value.

6.  Secondly, Mr Raffell says that the research which Dr Khaw was conducting was at a preliminary stage, and even if it turned out not to have been of any value, it is said that that does not mean that Dr Khaw could not have regarded it as having the potential for at least some value later down the line. The issue is not whether it was of no value, but whether Dr Khaw believed that it might have some value. I agree that that is the ultimate issue, but the jury’s consideration of that issue will be greatly informed by whether it really was of any value. If they conclude that it was of no value, that would be a factor – indeed a very important factor – in their determination of whether Dr Khaw could have believed that it might have been of some value.

7.  Thirdly, and this was Mr Raffell’s central point, far from being of no value, Dr Khaw’s research, he said, was ahead of its time. Mr Raffell referred to the research carried out by the authors of a recent peer-reviewed paper[1] published by a reputable publishing house. The paper was described by Professor Brendan Smith, Professor and Discipline Leader in Intensive Care and Specialist in Anaesthesia and Intensive Care at the University of Notre Dame in New South Wales, as follows:

“The biochemistry and toxicology discussed in this study strikes me as being exactly along the lines that Professor Khaw was thinking about back in 2010-2015, over a decade before this study was published. Work on reactive oxygen species (ROS) and peroxidation that Prof Khaw had done in the past has some striking parallels with this research. … Professor Khaw was, it seems to me, several years ahead in his thinking, rather than conducting bogus research as suggested by some of the more reactionary voices in HK!”[2]

So with one set of experts saying that it was of no value, and another set of experts saying that it could be at least of some value, there is said to be at the very least no room for the jury to be sure one way or the other. That especially applies to evidence which took many days to be given at the first trial, and was so complicated that at times even the judge was thankful for the arrival of the time when the court usually adjourned for lunch or the day.

8.  Mr Raffell developed this argument with great passion. Unusually for an advocate, he made no secret of what he himself thought the court should do. The difficulty, though, is that it is quite impossible for me to decide at this stage whether the evidence on the topic is so complex that the issue is simply not a justiciable one for a jury. But the real answer to Mr Raffell’s argument is the undoubted fact that juries are sometimes faced with experts with very different views on a topic with which the jurors may well be unfamiliar, and are having to reach a conclusion on the topic on evidence which is highly technical and complex. That has never been regarded as a reason for withdrawing the topic from the jury’s consideration. Nor should it be. Until the time comes – if it ever does – when cases involving technical and complex issues are decided otherwise than by juries, determining those issues will remain part of the jury’s function.

9.  The next strand of the argument advanced on behalf of Dr Khaw is that even if the research was of no value, that does not necessarily mean that the research was a sham – let alone a sham to hide what the prosecution say was his real reason for acquiring the carbon monoxide, which was to use it to kill his wife. That is true, but it does not mean that evidence about whether the research was of any value cannot be called. Whether it was a sham depended on what his reason for conducting the research was. That is a topic on which direct evidence may be given – whether from Dr Khaw himself if he elects to give evidence or from witnesses to whom he spoke about why he wanted to conduct this form of research. In addition it is a topic on which inferences may be drawn from other primary facts. One of those primary facts might be that the research had no value, and as I have already said, any conclusion on the part of the jury that the research had no value will inform their consideration of what Dr Khaw’s reason was for conducting the research.

10.  The next strand of the argument advanced on behalf of Dr Khaw is that in the light of the way the prosecution put its case at the original trial the question whether Dr Khaw’s research was of any value is irrelevant. The prosecution’s primary case may have been that this was not genuine research, but the jury was also invited to convict Dr Khaw on the basis that, even if the research had been genuine, he then opportunistically decided to use the carbon monoxide (which on this supposition he may have acquired for that research quite legitimately) to kill his wife. Since the route to conviction did not depend on whether the research was genuine or not, there was no need to burden the jury with that evidence – especially as it was detailed, highly technical and took up many days in the original trial.

11.  The flaw in this argument is that, if successful, it would force the prosecution to abandon its primary case, or at the very least make its primary case much weaker. There is, in my opinion, absolutely no reason why the advancement by the prosecution of an alternative case should have that effect on its primary case. The fact that there is a route to conviction without the prosecution having to rely on the research being valueless does not make the evidence that the research was valueless irrelevant. It is relevant to the prosecution’s primary case.

12.  The next strand in the argument advanced on behalf of Dr Khaw is that the exercise of exploring the value or otherwise of Dr Khaw’s research opens the door to a discussion of things which could be extremely prejudicial to Dr Khaw. Take, for example, the actual experiments which Dr Khaw did on rabbits. Some of them died as a result of the experiments. At least one of the experts called by the defence, Professor Nicholas Buckley, was cross-examined on whether these experiments should have been conducted at all without the prior approval of the University’s Animal Experimentation Ethics Committee. It is said that this line of questioning was potentially very prejudicial to Dr Khaw, and would not have occurred if there had been no issue about the value or otherwise of Dr Khaw’s research. Again, this argument gets Dr Khaw nowhere. If the prejudicial effect of this line of questioning outweighed its probative value, that would be a good reason for ruling that this line of questioning should not be allowed. It is no reason at all for disallowing the evidence relating to the value or otherwise of Dr Khaw’s research.

13.  I was told that Professor Buckley would not be giving evidence in the retrial. That makes no difference. The issue relates to the nature of the cross-examination, not who is being cross-examined on the topic. So if the prosecution propose to examine or cross-examine any witness on the topic, and the defence wish to argue that the prejudicial effect of this line of questioning outweighs its probative value, they should argue the appropriateness of that at the relevant time in the absence of the jury.

14.  There is a second example of what is said to be the danger of exploring the value or otherwise of Dr Khaw’s research. Professor Buckley was asked in cross-examination what he thought of transporting carbon monoxide in a yoga ball. He said that it was “crazy”. The criticism is that this was not his area of expertise. Again, if this was a question which should not have been asked, the remedy now is to prevent the prosecution from asking it in the retrial. Ruling that no evidence should be given about the research would be a classic example of throwing the baby out with the bathwater.

15.  Finally, the defence contend that the experts called by the prosecution in the first trial did not have the expertise to express an opinion on the validity or otherwise of Dr Khaw’s research. Again, that was not suggested at the first trial, but since the prosecution propose to call the same experts in the retrial, it is open to the defence to contend that. They are not bound by the strategy adopted or the absence of submissions on a particular topic in the first trial. However, the current question is whether expert evidence can be given at all on the validity of Dr Khaw’s research, not whether any of the proposed expert witnesses have the expertise to express an opinion about that. A lack of expertise on the validity or otherwise of Dr Khaw’s research could only prevent a particular expert witness from giving evidence about that. That is very different from saying that evidence about the validity or otherwise of Dr Khaw’s research is inadmissible as irrelevant to any issue which the jury has to decide.

16.  That is not to say, of course, that the defence cannot contend that a particular expert witness lacks the expertise to give evidence on a particular topic. But since they wish to do that, they must do so in the proper way. The proper way is for the witness to be examined and cross-examined on the nature and extent of his expertise in the jury’s absence. I will then determine, in the light of that evidence, whether the witness has the necessary expertise or not. Since the prosecution wished to open to the jury their case that Dr Khaw’s research was of no value, I had to decide – in respect of at least one of the expert witnesses who the prosecution proposed to give evidence on the topic – whether he had the necessary expertise to do so. That was why Professor Irwin was called to give evidence this morning. However, I was told this morning that the defence no longer contend that Professor Irwin does not have the expertise to express an opinion on the validity of Dr Khaw’s research. Unless the defence change their stance in respect of the witnesses who the prosecution propose to call to give evidence on the topic, they will have to be examined and cross-examined on their expertise in the absence of the jury in the way in which Professor Irwin would have been today.

17.  For all these reasons, I rule that the prosecution may call evidence to show that Dr Khaw’s research was of no value.

D.  The eradication of rats

18.  The defence ask the court to take judicial notice that carbon monoxide can be used to eradicate rats. They rely on google searches before May 2015 and between 2023 and 2024. The information given to Google was “rodent control carbon monoxide”, and it produced many hits. The websites of three pest control firms or companies offering to eradicate rats or rodents using carbon monoxide before May 2015 have been reproduced, as well as the website of one such firm or company in the more recent search. Also reproduced from the earlier search is a technical evaluation report from a pesticide research institute asking for exhaust gas (which contains carbon monoxide) to be allowed in organic crop reduction in connection with “underground rodent control”. All these materials come from the United States.

19.  As is well known, the court can take judicial notice of a particular fact if the fact is so well known to the court that it would be a waste of time and resources to require the party seeking to rely on that fact to prove it formally by admissible evidence. In the case of trial by jury, the court for this purpose are the members of the jury. So the question is whether the members of the jury, all of whom have to be residents of Hong Kong, would know that carbon monoxide can be used to eradicate rats. If they were asked the question: did you know that carbon monoxide could be used to eradicate rats, would they all say – perhaps a little testily for being asked something so obvious – “Yes, of course”? In my opinion, they would not all say that. It may be that one or two might, but only, I suspect, if they had wanted to find out how to get rid of rats.

20.  But that presupposes that the test for taking judicial notice of a particular fact is only if the fact is so well known that ordinary people can be expected to be aware of it. But that is not correct. The court can also take judicial notice of a particular fact if it is “susceptible of demonstration by reference to a readily obtainable and authoritative source”.[3] What the websites reproduced by the defence has shown is that there are pest control companies which offer a service which involves the use of carbon monoxide in the eradication of rodents. But whether that service is successful is another matter. The mere fact that pest control companies say that carbon monoxide can eradicate rodents does not mean that they can. And on this topic the evaluation from the pesticide research institute is of little value as the focus of the report is on whether a synthetic substance such as exhaust gas should be allowed in organic crop production. So if judicial notice is to be taken of anything, it can only be that there are a few pest control companies in the United States which offer a service which purports to use carbon monoxide in the eradication of rodents. Such judicial notice cannot go so far as to say whether such a service is capable of being successful.

21.  Moreover, if judicial notice is to be taken of this limited fact, it cannot relate to the quantity of carbon monoxide which should be used to eradicate rodents in a domestic setting. If the searches relied on by the defence are anything to go by, it is only a tiny amount of carbon monoxide which is needed for the purpose of eradicating rodents. That is because the materials produced by Mr Raffell show that only 2.5% of the gases which make up exhaust gas consist of carbon monoxide. There is said to be a dispute about that in view of what Dr Khaw is alleged to have said when he was interviewed by the police. So the amount of carbon monoxide necessary to eradicate rats from Dr Khaw’s home will have to be proved by admissible evidence – whether it is the prosecution seeking to prove that the amount of carbon monoxide which Dr Khaw took home was far too much to kill rats at home with, or whether it is the defence who are seeking to prove that the amount of carbon monoxide which he took home was no more than he needed for that purpose.

22.  Google would not be an authoritative source for the assertion that using carbon monoxide to eradicate rodents works. But it is an authoritative source for ascertaining whether there are pest control companies which offer that service. I am therefore prepared to take judicial notice of the fact that there are a few pest control companies in the United States which offer a service which purports to use carbon monoxide in the eradication of rodents. No more than that.

23.  The defence point out that Dr Khaw as an anaesthetist would know about the properties of various gases, and as someone who lived in a village near a wood, he was more likely to have a problem with rats than people who lived in other settings. The suggestion, I presume, is that he is therefore very likely to have known that carbon monoxide can be used to kill rats. Assuming for present purposes only that that is true, it does not get the defence anywhere. The test for determining whether to take judicial notice of this use of carbon monoxide is not whether Dr Khaw knew of this particular use of carbon monoxide, but whether it was generally known.

24.  I should add this in case I have been missing something. I am not sure why the parties are so fussed about the issue. If it be the case that carbon monoxide can be used to eradicate rats, the point cuts both ways. The defence can rely on it to show that it was for that reason entirely plausible for Dr Khaw to take the carbon monoxide home. But for their part the prosecution can say that Dr Khaw was using his knowledge about the uses to which carbon monoxide can be put to provide an innocent explanation for having taken carbon monoxide home when his real reason for doing that was to kill his wife. The real issue is whether the amount of the carbon monoxide which he took home was consistent or inconsistent with what he said he was taking it home for.

25.  Having said that, for the reasons I have given, the court will only take judicial notice of the fact that there a few pest control companies in the United States which offer a service which purports to use carbon monoxide in the eradication of rodents.