Legal Updates

Applying Medical Evidence from the Study of Aetiology to Causation in Law: CHIU KWAI YUK V LEE TAK WAH AND OTHERS [2022] HKDC 59

Chiu Kwai Yuk for herself and on behalf of members of the family of Lee Chi Wai, deceased v Lee Tak Wah trading as Hatco Exhibition Production Company and Ascent Exhibition Design (Hong Kong) Limited and Employees Compensation Assistance Fund Board

DCEC 2838/2017; [2022] HKDC 59
Date of Judgment: 27 January 2022


This was an action for Employees’ Compensation. The deceased was employed for one day by the 1st Respondent, the sub-contractor of the 2nd Respondent, to carry out decoration. The deceased worked overtime on that day and collapsed after taking a cigarette break. He was certified dead after attempted cardiac resuscitation. The cause of his death was cardiac arrest from Acute Myocardial Infarction (“AMI”), which was more commonly known as a heart attack.


Section 5 of the Employees’ Compensation Ordinance (Cap. 282) provides that “… if in any employment, personal injury by accident arising out of and in the course of the employment is caused to an employee, his employer shall be liable to pay compensation …

The issue was one of causation, namely, whether the AMI was caused by an accident, and whether this accident arose out of and in the course of the employment.


The judgment was handed down by Judge Harold Leong in the District Court.

Held, dismissing the action, that:

  1. This case illustrated the problem of attempting to apply the medical evidence from the study of aetiology to the issue of causation in law.
  2. What the experts disputed in the present case was the cause (or “trigger”) of the plaque rupture, leading to bleeding with the resulting clot completely blocking the lumen of the coronary artery.
  3. In law, a causal link exists if it is proved on a balance of probabilities that “the accident was a substantially contributing cause of the injury” (para. 16).
  4. By contrast, the medical study of aetiology, which attempts to identify “risk factors” for a particular disease, is essentially a forward looking study and it does not look at a case retrospectively. For instance, the study of aetiology may not distinguish if a particular case of stomach cancer is “substantively contributed to” by the intake of preserved meat or if it is a “background” incidence. Aetiological “risk factors” might only show that there is a statistical correlation between such “risk factors” and an increased incidence of the accident over a background level of incidence. The evidence does not show if a particular case is a background incidence or not. This was exactly the problem in the present case, since most ruptures were spontaneous (with no identifiable trigger or cause) and there were identifiable triggers in a small proportion of rupture cases only.
  5. Importantly, there was no medical investigation or test that could verify the trigger or cause of a plaque rupture.
  6. The fine distinction between medicine and law above might not be that important in most cases of “traumatic” accidents. For example, there is unlikely to be any “background occurrence” of spontaneous ankle fracture so if somebody fell from height and his or her ankle fractured, there is no question that the fall would have, on a balance of probabilities, “substantially contributed” to the fracture of the ankle.
  7. The problem arises for incidents of “non-traumatic” accidents, such as AMI in the present case, which could be insidiously developing over a number of years by various “risk factors” which may be related or unrelated to employment cumulating on the one moment: the triggering event (the plaque rupture in the present case) which caused the injury.
  8. The problem is whether it is possible to identify the triggering event when there is no medical investigation test to identify the triggering event, if any, and the period between the triggering event and symptoms appearing is unpredictable.
  9. Where the medical experts could not render medical evidence which is strong enough to support the legal issue of causation, they should not be tempted to pick one or another of those aetiological “risks factors” (or “quasi risk factors”) as the “cause” since much of that would have been done on the basis of speculation.
  10. In the present case, there was not enough evidence to support that the death of the deceased arose out of his employment. The action was, therefore, dismissed.
Skip to content