YIU YAN CHE by YIU WAI YU his next friend v. YIU CHO YUEN

HCA 1363/2024

[2026] HKCFI 2515

IN THE HIGH COURT OF THE

HONG KONG SPECIAL ADMINISTRATIVE REGION

COURT OF FIRST INSTANCE

ACTION NO 1363 OF 2024

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BETWEEN

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REASONS FOR DECISION

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Introduction

1.  This is the hearing of the Defendant’s appeal against the orders made by the Master at a short hearing on 11 February 2026.

2.  The way in which the appeal came to be brought about is fairly unusual. At the hearing before the learned Master, where the Plaintiff was represented by counsel and the Defendant by solicitors, the matter before the Court was a consent summons which had been filed on 5 February 2026.

3.  Paragraphs 2 and 3 of the consent summons provided that:

“2. Leave be granted to the parties to each adduce evidence from one expert on the following issues:-

a. whether the Plaintiff had mental capacity:

i. as at 1 June 2023, in respect of the purported execution of the Sale and Purchase Agreements, Instruments of Transfer and Bought and Sold Notes for Million-Add Development Limited, Memoran Company Limited and Chung Tung Investment Limited;

ii. as at 11 July 2023, in respect of the purported execution of the Sale and Purchase Agreements, Instruments of Transfer and Bought and Sold Notes for Add-Field Investment Limited and Grandpop Development Limited (collectively, “Impugned Documents”);

iii. as at 11 August 2023, in respect of (a) purportedly effecting, causing and/or agreeing to the transfer of HK$3.9 million from his account held with Bank of China (Hong Kong) Limited (the “HK$3.9M Transfer”); and (b) purportedly effecting, causing and/or agreeing to the HK$3.9M Transfer for the purpose of paying stamp duty incurred in respect of the purported transfers pursuant to the Impugned Documents;

b. whether each of the assessments conducted by Dr Hung Bing Kei, Gabriel on 1 June 2023 and by Dr. Yu Wai Tak, Peter on 11 July 2023 was sufficient and/or satisfactory for the purpose of ascertaining Plaintiff’s mental capacity in respect of the matters set out in paragraph 1(a)(i)-(iii) above; and

c. whether Plaintiff was or was likely to be more susceptible to undue influence in respect of (i) the execution of the Impugned Documents; and (ii) the HK$3.9M Transfer, in view of his mental condition and/or medical history as at each relevant time.

3. Leave be granted to the Defendant to adduce as expert evidence:

a. Dr. Hung’s (i) 3 medical certificates dated 1 June 2023, (ii) medical report dated 25 February 2025; and (iii) medical report dated 12 September 2025;

b. Dr. Yu’s medical certificate dated 11 July 2023 together with his contemporaneous notes and MMSE test report; and

c. Any further reports of Dr. Hung and/or Dr. Yu in respect of their respective assessment conducted on 1 June 2023 and 11 July 2023 to be filed and served within 21 days of the order to be made.”

4.  As Mr William Wong, who appeared before me and made helpful and skilful submissions, pointed out, the appeal is very narrow in scope.

5.  It is important to point out in the present case, for the reasons which I will explain in more detail below, that the Plaintiff has adopted a neutral stance in this appeal. It indicated so by way of a letter to the court dated 26 March 2026. At paragraph 7 of their letter, they stated: “In view of the above and in hopes of saving the court’s time... attendance be excused at the upcoming hearing of the notice of appeal.”

6.  On 2 April 2026, Madam Justice Au-Yeung approved the application. Therefore, they were not represented before me today.

7.  The substance of the appeal concerns the Defendant seeking the reinstatement of paragraph 3 of the parties’ consent summons, which was the part which had been disallowed by the Master.

8.  By that, the Defendant sought leave to adduce, as expert evidence, medical certificates and reports prepared by two psychiatric doctors, namely, Dr. Hung and Dr. Yu, who had assessed the father’s mental capacity at the time of the relevant documents, which are being challenged in the substantive proceedings.

9.  There are, in any event, experts who had been appointed by the respective parties for the purpose of conducting an ex post facto assessment. It would appear that the learned Master’s fundamental concern at that time was to limit the number of experts and possibly try to control costs, notwithstanding the parties’ consent as per the consent summons.

10.  In my view, the Master’s approach, generally speaking, was laudable in that the court is not a rubber stamp and, of course, it is for the court, notwithstanding the parties’ consent on certain occasions, to ensure that the underlying objectives of the Rules of the High Court are being complied with.

Brief background

11.  The Plaintiff in these proceedings, who is the father and brings this action by his next friend, sues the Defendant, who is the eldest son of the family. There is no need to get into the crux of the dispute, but in short, a number of agreements were entered into which are now sought to be challenged by the Plaintiff on the basis that they are null and void because it is suggested that the father lacked mental capacity, or alternatively undue influence was exerted on the father by the Defendant.

Discussion

12.  In this case, as in many cases, one of the key issues is that of mental capacity of a person at a particular time, and as in many cases where such issues arise, doctors or the medical personnel who had conducted examinations would be called to give evidence. The issue is whether they are merely called as factual witnesses, or whether they should be treated and considered as expert witnesses in which case leave needs to be sought and obtained.

13.  The decision of Mr Justice Bharwaney in Hung Sau Fung v Lai Ping Wai [2012] 1 HKLRD 1 is particularly apposite. This authority was helpfully drawn to my attention by Mr Wong, but I understand that for the reasons explained above, the learned Master did not have the benefit of that authority being drawn to his attention.

14.  At paragraph 46, in the context of a personal injuries case and in particular whether leave should be obtained for adducing expert evidence, his Lordship held as follows:

“The report of a treating doctor is always admissible to prove the fact that the injured person was receiving treatment, the nature of that treatment, and the opinion and diagnosis of the treating doctor which was communicated to the injured person. These are all matters of fact. Whilst the diagnosis reached and the treatment plan recommended by the treating doctor is the product of his expertise, his diagnosis and treatment plan and their communication to the injured person is a matter of fact. However, the opinions expressed by the treating doctor in his report are not admissible as expert evidence unless leave to admit it for that purpose has been obtained from court. That principle is easy to state but sometimes difficult to apply. It is often a difficult and time-consuming exercise to redact parts of a treating doctor’s report containing his expert opinion, which is admissible only with the leave of court, from those parts of the same report setting out his diagnosis and the opinions he has expressed to his patient, which are always admissible as matters of fact.”

15.  I respectfully agree with those observations and I note that by way of example only, in the decision of Angela Chen v Chen Wai Wai [2026] HKCFI 1269 (an unreported decision of Madam Justice Winnie Tsui dated 27 February 2026), her Ladyship had recorded at paragraph 11 of the judgment that leave had been granted to one of the parties to rely on what her Ladyship called historical reports which were made by three different doctors throughout a period of seven years, and in that particular case there were 16 such reports.

16.  On his feet, Mr Wong highlighted three points.

17.  First of all, he drew attention to the fact that the Plaintiff in the present appeal adopted a neutral stance which reflected recognition as to the need of having those who have provided contemporaneous expert medical certificates to be called as experts, the fact that the matter’s origin was based on consent as recorded by the consent summons between the parties, and the fact that the said medical practitioners had examined the father on the very day the transactions were signed and approved.

18.  Secondly, whilst he accepted that the court was always entitled, and indeed duty-bound, to exercise robust case management, the evidence given by the two doctors in this case would be “direct and probative”.

19.  Thirdly, whilst he appreciated and agreed fairly that there was a fine line between doctors giving factual evidence only and doctors giving expert evidence only, the line was sometimes not easy to discern. Indeed, in some earlier cases it has been referred to as a ‘grey area’. He further pointed out, in my view correctly, that on the facts of this particular case, if the two doctors were only to be confined as “factual” witnesses rather than expert witnesses, any costs savings would be marginal. On the other hand, allowing them to be called as expert witnesses would be of a highly probative and material value to the trial judge.

20.  It seems to me that there is no hard rule on such cases. Ultimately the court must balance various discretionary considerations including controlling costs, trial time, and also look at the probative value and whether or not the suggested time savings are more theoretical than real. On the facts of the present case and having had the benefit of written skeleton submissions and authorities, I come to the view that it is appropriate to allow the two doctors to give evidence as experts rather than only as witnesses of fact.

21.  It also seems to me that once this is recognised, the experts who will conduct an ex post facto examination of the matter can then look both at the reasoning of the medical practitioners who had conducted contemporaneous examinations as well as the reasoning of the expert now called by the other side to do an ex post facto analysis, and he can deal with any issues arising out of their methodology or other basis in one go.

Conclusion

22.  All in all, whilst I have a considerable degree of sympathy for the learned Master who dealt with the matter as robustly as he could and as I have said above, his approach was laudable in that he did not seek simply to rubber-stamp the consent of the parties; having had the benefit of further submissions and more time on the matter, it seems to me right that the two doctors be allowed to give evidence as expert witnesses and for those reasons, I have allowed the appeal. I note that the notice of appeal asks for costs in the cause and I will also allow for the same.

(Consequential directions)