Bryont Chin

Torn Fealty to the Courts and Science: Conundrums over Medical Expert Opinions (II/II)

By Agnes Lo, Bryont Chin, Darren Ang, Leon Tay & Louis Lai*

The previous section of this article examined the different considerations that affect the weight accorded to expert evidence.1 It was observed that judges scrutinize the expert himself (his qualifications and the level and relevance of his specialization) and also his testimony (its cogency, internal consistency, and consistency with the facts).

A survey of local case law and overseas publications reveals issues surrounding this assessment. These have been directed to the reliability of expert opinions itself, applying generally to all experts. Unfortunately, local jurisprudence has not addressed these concerns.

The lacuna in local jurisprudence on this point is especially unfortunate given the widespread prevalence of and reliance upon medical expert opinion in Singapore. It is thus pertinent to examine these issues and their causes in detail.


A. Partiality and bias of experts

Case law reflects a persistent concern about the partiality and bias of experts but also a recognition that this will persist as long as litigation remains adversarial. Ideally, under Order 40A Rule 2(2) of the Rules of Court2 [ROC], experts should bear an exclusive duty to the Court; however, this is usually not the case in practice. A “market-place” mentality continues to prevail: parties select experts because the latter’s views are “already known and, consequently, would advance the party’s case.”3 Both the courts and commentators like Professor Pinsler have acknowledged that the source of this paradigm is the adversarial model, since parties assume that their “remuneration of the expert justifies a measure of loyalty that will somehow manifest to his advantage in the determination of the case before or at trial”.4 Therefore, as long as the adversarial model continues to be adopted, parties will continue to pay, retain, and offer the experts future engagements—all of which incentivise experts to provide opinion evidence slanted in favour of the clients who engage them.5

To make matters worse, breaches of the procedural duty under Order 40A above attract no direct penalties in themselves. There is only an evidential penalty: if an expert is found to be partial, the court completely or partially disregards his testimony.6 This does not seem to have been enough: from the introduction of Order 40A in 2000 to date, the courts have continued to observe bias in experts.7 Therefore, bias among experts remains a real problem in the court today.

B. A fear of testifying in Court

Also flowing from the adversarial model and the process of adjudication itself is medical experts’ intrinsic fear of testifying in court. Experts—and medical experts in particular—tend to steer clear of the witness stand for two reasons: a fear that they may not be sufficiently competent to testify, and a fear that they may be shamed or wronged on the stand.8

While there is no equally comprehensive study, local doctors have expressed the same fears of testifying due to natural embarrassment and a fear of damaging their colleagues’ reputations.9 Failing to address these fears will restrict plaintiffs’ access to medical experts or otherwise make engaging experts more expensive. This reluctance will affect the quality and accessibility of court adjudication, reliant as it is on expert testimony.

C. Insufficiency of factual bases for medical opinions

Experts often have insufficient facts to support their opinion. This is because in litigation, they are likely to be engaged before trials begin since their opinions are critical in establishing the client’s case and thus predict the likelihood of success at trial.10 However, this means that much of the evidence the expert relies upon to develop his report and testimony will be “untested raw material” since this evidence has yet to be tested in court.11 This concern came to a head in Khoo Bee Kiong,12 where the court expressly questioned the factual basis of an expert opinion prepared with affidavits of evidence in chief.

This is likely to be aggravated in medical negligence claims, where the recent Supreme Court Practice Directions13 impose an accelerated case management timeline. As an expert report must now be filed before the claim itself begins, medical experts have less time and evidence to formulate their opinions.


Apart from issues with the expert opinions themselves, there are also notable concerns with the judicial treatment of medical expert opinions as reflected in empirical studies. These suggest that there are systemic issues with judges’ ability to assess the reliability and credibility of a medical expert’s opinion and the proper weight to be accorded to admitted evidence.

A. Lack of clarity on the assessment of reliability and credibility of medical expert opinions

At its core, the court’s assessment of the reliability and credibility of a medical expert’s opinion is a discretionary exercise. It is naturally opaque and applied circumstantially, and may hence appear uncertain. This means that the other stakeholders involved—lawyers, clients, and the medical experts themselves—may not fully understand the standard expected of them. Jurs, for instance, observes that legal professionals tend to over-estimate the value of personality and credentials, whereas judges place a greater emphasis on partiality and bias, tentativeness, and the technicality of the opinions proffered.14 Clarity in this area is much needed;15 consensus and better articulation of the relevant considerations would assist greatly.

B. Assessment of weight to be accorded to admitted medical expert opinions

Beyond a lack of clarity on a systemic approach to assess reliability and credibility of medical expert opinions, there is a concern that the current approach may mean that factors which might appear to be unrelated or insignificant may be taken into account in the assessment of weight to be accorded to admitted expert opinions. For instance, “impressions of the analyst’s demeanour and credibility, like the ability to survive cross-examination, will not in most cases provide rational means of assessing the probative value of an opinion.”16 The English courts, for example, have been criticised for assessing expert opinion evidence on this basis, which has led to factually unsustainable acquittals.17

Studies suggest that this concern may not be unfounded because of the way medically-untrained judges and jurors assess the value of medical expert opinions. For instance, jurors focus on consensus supporting the expert opinion, whether the opinion is applicable in the case at hand,18 and how experts communicate their opinions.19 However, these indicators may not necessarily go towards the veracity of an opinion.20 Where earlier studies have suggested that this may be due to a lack of education in the expert’s field,21 it is understandable why some doctors feel that laypersons like jurors “should not decide medical malpractice cases because of the arcane issues involved in the practice of medicine.”22

Local jurisprudence has only engaged these concerns in the abstract. Ronald Wong posits that the law’s insistence on the finality of an opinion for it to be accepted as evidence conflicts with the scientific method, which relies not on finality, but rather social acceptance to establish a theory as valid.23 This mirrors the observation in Levett and Korvera’s review that “individuals often are unable to evaluate statistics or methodology properly… [such that] it is reasonable to assume that jurors may be unsuccessful in independently detecting flaws in research presented by an expert in court.”24 Nonetheless, Wong has argued that it is still preferable for a judge to continue to adjudicate on the issue, and if the expert evidence is insufficiently reliable, a judge ought to make his findings of fact on the burden of proof.25 Wong’s argument—defended on grounds of a public interest in resolving disputes—contrasts with Professor Hor’s view that judges lack any institutional capacity to determine the veracity of expert opinion.26

Since judges must still decide cases involving expert opinions, the question of institutional competence remains a live issue to be managed. This is especially the case if adjudication may lead to imperfect reliance on wrong or inaccurate expert opinions as suggested by the studies above.


Concerns over unreliable expert opinions have been the subject of statutory reform. The government has astutely institutionalised a court-appointed panel of psychiatrists testifying in criminal cases under the new s 270 of the Criminal Procedure Code27 [CPC] which has not yet come into force.28 This places the control over the admission and use of psychiatrists’ opinions in the hands of a Selection Committee instituted for these purposes.

In other aspects, however, reform continues to be lacking. The independence of experts continues to be secured by weak duties under s 269 CPC which do not depart from the phraseology of Order 40A ROC. The amendments to the CPC do not address the deeper concerns relating to adversarial litigation or pronounce on the feasibility of alternatives such as independent experts or assessors.

Therefore, the fundamental question remains as to whether the amendments will indeed improve the reliability of psychiatric evidence and be a viable option across other classes of medical experts as well; or, alternatively, whether it would entrench a preferred doctrine of psychiatric testimony.29 If the latter is the case, then the amendments may exacerbate the issue of expert witness bias. Psychiatrists have questioned why they were the only class of expert that required supervision, while the Criminal Bar expressed that it would be preferable if the selection process also included defence counsel as a member of the Selection Committee.30

Beyond the concerns regarding the partiality of experts, there are also practical complications of note. Amendments have been made to the Supreme Court Practice Directions to require medical expert opinion reports to be submitted in the pre-writ exchange of information for medical negligence cases, but this may mean that experts will not have sufficient factual evidence to support their opinions.31 These remain with broader concerns that judges may lack the institutional capacity to accurately assess medical expert opinions, or that they may demand a different standard from non-medical expert witnesses. While there are extra-legal methods employed to cope with these such as a training course for medical experts to raise the quality of medical opinions and reports, the impact of these courses on the judiciary’s assessment of the medical opinions and reports presented to them, has not yet been observed.


The discussion above has traced a number of difficulties in the use of medical experts’ opinions, as well as the use of experts in general. The judicial approach to assessing the probative value and reliability of opinions is plagued with difficulties stemming from intractable concerns that medical experts tend to be partial towards the party that hired them, and that such experts often lack sufficient facts to properly develop an opinion. Although there are both existing procedural laws and external support to safeguard the reliability of medical expert opinions, these are often watered down by parties’ adversarial mentalities. Where there is little incentive to cooperate, parties do not actively rely on the same measures such as concurrent expert evidence or discussion. Other issues, such as fear among medical professionals of proffering testimony against their fellow doctors, or the institutional competence of the Court to adjudicate on the same, have hardly been the subject of discussion by the legal community in Singapore.

This is unfortunate as expert opinions are the lifeblood of many disputes. Even before a case commences, expert opinions are important in managing client expectations, where the expert’s assessment indicates the client’s likelihood of success.32 Medical experts are of special significance in the field given that they are relevant in many legal disputes and, in fact, comprise the bulk of experts sought.

Meeting the concerns above would require lawyers, judges, and medical experts alike to come to a clear consensus on their roles and competencies in adjudication. Coping with the difficulties of an adversarial model will also require a change in mindset and culture: lawyers and courts must emphasise to medical experts that in testifying, they are helping society as a whole. In this regard, the authors posit that empirical studies will be helpful in assessing the gravity of each issue, and the effectiveness of measures to cope with them. In this regard, this article will be followed by a further submission, “The Evaluation of Medical Expert Opinions in Litigation: An Empirical Study”,33 which seeks to provide more clarity on the factors that judges in Singapore apply in evaluating medical expert opinion evidence, and their relative significance in different scenarios.

*The authors are a group of undergraduate students in the National University of Singapore, and are presently in the course of an empirical research project on the subject.

[1] See Agnes Lo, Bryont Chin, Leon Tay & Louis Lai, “Torn Fealty to the Courts and Science: Conundrums over Medical Expert Opinions (I/II)”, online: Juris Illuminae, Vol 10 <>.

[2] Cap 322, R 5, 2014 Rev Ed Sing.

[3] Jeffrey Pinsler, “Expert Evidence and Adversarial Compromise: A reconsideration of the Expert’s Role and Proposals for Reform” [2015] 27 Sing Ac LJ 55 at [2].

[4] Ibid at [15].

[5] Vita Health Laboratories Pte Ltd v Pang Seng Meng [2004] 4 SLR 162, at [81].

[6] If the expert attempts or is seen to be an advocate for his party’s cause, he will inexorably lose credibility: per VK Rajah JA in Vita Health Laboratories Pte Ltd v Pang Seng Meng [2004] 4 SLR 162 at [83].

[7] Supra note 3 at [4].

[8] See e.g. “Medical Malpractice - Expert Testimony” (1965-1966) 60 Nw UL Rev 834.

[9] See Joseph Sheares, “Writing the Expert Report and Testifying in Court (Part 2)”, SMA News (February 2015) at 23, online: < %20SMA%20News/4702/Professionalism.pdf>.

[10] Amanda Stevens, “Editorial: Reliability and cogency of expert witness evidence in modern civil litigation” (2011) 66 Anaesthesia 764.

[11] Khoo Bee Keong v Ang Chun Hong [2005] SGHC 128 at [72].

[12] Ibid.

[13] See Sing, The Supreme Court Practice Directions (2017) part XXIII, s 158(1), referring to Appendix J (High Court Protocol for Medical Negligence Cases), online: <> at 4.1-4.2.

[14] Andrew W Jurs, “Expert Prevalence, Persuasion, and Price: What Trial Participants Really Think About Experts” (2016) 91 Ind LJ 353 at 371-372, 377-378 and 389.

[15] See e.g. the Ministry’s comments in proposing amendments to s 270 of the CPC, which it expressed to be for the purpose of ensuring that evidence given by psychiatrists is “competently arrived at and objective”: Siau Ming En, “Proposed psychiatric panel must be large enough for smoother defence: Lawyers”, Today (28 July 2017), online: <>.

[16] Gary Etmond, “Legal versus non-legal approaches to forensic science evidence” (2016) 20:1 IJEP 3 at 24.

[17] Ibid.

[18] Lora M Levett & Margaret Bull Korvera, “The Effectiveness of Opposing Expert Witnesses for Educating Jurors about Unreliable Expert Evidence” (2008) 32:4 Law and Human Behaviour 363-374, at 364.

[19] Andrew W Jurs, “Expert Prevalence, Persuasion, and Price: What Trial Participants Really Think About Experts” (2016) 91 Ind LJ 353.

[20] Kovera MB, McAuliff BD & Hebert KS, “Reasoning about Scientific Evidence: Effects of Juror Gender and Evidence Quality on Juror Decisions in a Hostile Work Environment case” (1999) 84:3 J Appl Psychol 362 at 365.

[21] See e.g. Kalven, Harry Jr & Hans Zeisel, The American Jury (Chicago: University of Chicago Press, 1966) at 153; cited in Sanja Kutnjak Ivkovic & Valerie P Hans, “Jurors’ Evaluations of Expert Testimony: Judging the Messenger and the Message” (Cornell Law Faculty Publications, Paper 385, 2003) at 443.

[22] Neil Vidmar, “Lay Decision-Makers in the Legal Process” in Peter Cane & Herbert M Kritzer, The Oxford Handbook of Empirical Legal Research (OUP, 2010) 626, at 633.

[23] Ronald JJ Wong, “Judging between Conflicting Expert Evidence” (2014) 26 Sing Ac LJ 169.

[24] Supra note 18.

[25] Supra note 23.

[26] Ibid, citing Michael Hor, “When Experts Disagree” (2000) Sing JLS 241 at 243.

[27] Cap 68, 2012 Rev Ed Sing.

[28] Clause 78 of the Criminal Justice Reform Bill (Bill 14 of 2018), which introduces s 270 of the CPC.

[29] Supra note 15.

[30] Ibid.

[31] See Appendix J of the Supreme Court Practice Directions (Amendment No. 3 of 2017). The relevant amendments to the Practice Directions are available online at <>.

[32] Supra note 10.

[33] Lo et al., “The Evaluation of Medical Expert Opinions in Litigation: An Empirical Study” (2018–2019) 36 Sing L. Rev. 247.

The PDF version of this article is available for download here.

Torn Fealty to the Courts and Science: Conundrums over Medical Expert Opinions (I/II)

By Agnes Lo, Bryont Chin, Leon Tay & Louis Lai


The Singapore courts are well-accustomed to hearing technically complex disputes, and disputes involving medical issues may present the most complex of these cases. Where judges and counsel are unable to divine the implications of facts and evidence at hand, they inevitably turn to expert witnesses. Expert witnesses assist in interpreting the facts, opining on what these facts mean, and provide specialized knowledge and information so very crucial for a judgment to be made.

Expert witnesses have become necessary ever since complexity in technical matters increased beyond a layman’s untrained capacity. It was understood that when the machines inevitably got involved in disputes, judges had to call on experts to advise them. However, judges do not blindly defer to the authority of the expert. Care is necessarily taken to differentiate between different opinions proffered by each expert, and not every testimony is given equal weight or admitted without any questions. A clear example where the judge departs from the views of an expert is where the expert witness is biased. Another possible difficulty is in finding an objective approach to evaluate competing expert opinions. In such situations, whose opinion is to be preferred and given more weight? Is a professor’s academic opinion more reliable than that of an experienced practitioner lacking in qualifications? These questions continue to plague the courts today.

In a two-part series, this article sets out a preliminary examination of the main factors considered by the court in assessing the proper weight to be given to expert testimony. Medical experts are given foremost consideration as they feature prominently among the expert witnesses appearing before the courts. In a following article, we will also examine inconsistencies and incoherence in the courts’ use of expert evidence, and discuss recommendations for future use of expert evidence.

A. The use of medical experts in court

Medical expert opinions are widely admitted in criminal and civil trials. In criminal cases, these opinions are necessary to determine the psychological or physiological state of the accused persons, from which the judge can establish the legal elements of the offence. When deciding on sentencing, expert opinion also informs the judge of facts from which he can find exacerbating or mitigating factors. In civil matters, liability of the accused and damages to be awarded often depends heavily on the assessment of a medical expert. After all, judges are hardly able to decide what an appropriate sum for medical expenses should be, or how much income would have been lost as a result of an injury. Of course, medical expert opinions are most often adduced in physical injury cases,1 and when trespassing into the realm of medical expertise, judges are loath to substitute their own views for those of the proper experts in the field. In this regard, judges thus place a greater weight on the testimony of a defendant doctor’s own peers, since they—having the most similar qualifications and experience—would be most able to give advice.

B. The present litmus tests for the admissibility and reliability of opinions of medical experts

Prior to the introduction of the adversarial criminal system in the 18th century, there was no legal procedure to define experts qua expert witnesses;2 experts would usually be summoned as jurors or witnesses. Evidentiary rules and objections were subsequently developed to standardise the types of evidence and how they can be presented before the court. While the rule against opinion being admissible as evidence emerged alongside the prohibitive rule against hearsay, experts’ opinions are an exception to this otherwise strict rule. This exception was necessary in the adversarial system for experts to provide opinions as witnesses without having observed the facts.

The present legal framework for the admission and giving weight to expert evidence bears two stages of analysis. Judges as finders of fact must contend with the question of whether the expert’s opinion is admissible as evidence, and if so, whether the expert’s opinion is of sufficient weight to be relied upon to establish a fact in issue. The former is governed largely by Section 47 of the Evidence Act and interpretive cases, while the latter is largely a matter expounded upon by case law.

Section 47 of the Evidence Act essentially requires counsel to establish three points to admit expert opinions as evidence:

(a) The pleaded point must be one of “scientific, technical or other specialised knowledge”.3 The ambit of such knowledge and whether a particular field would fall within it seems to be open to discussion, and local courts have yet to pronounce on the specific test. There have been suggestions for reference to tests in foreign jurisprudence, such as the more lenient test in Frye v United States4 (“Frye”); or a more stringent inquiry under Daubert v Merrell Dow Pharmaceuticals.5

(b) The individual giving the opinion must be an expert, who must have obtained the knowledge applied in his opinion “based on training, study or experience”.6 A judicial determination of whether this is made out is discretionary, and often turns on the qualifications, experience, and credibility of the expert in question.7

(c) In the round, the Court must be “likely to derive assistance” from the opinion when making its determinations of fact. This is a lower threshold than that under the same provision before the 2012 Amendments to the Evidence Act.

Once admitted, the court generally gives weight to the expert opinion unless it is later found to be “obviously lacking in defensibility”.8 In cases where only one expert opinion is adduced or where the experts are in agreement, there are few obstacles that may lead to the courts giving it less weight. This is contrasted to cases where competing expert opinions are adduced in court: in such cases, a brief survey of cases involving medical experts affirms that a multi-factorial approach is taken. Some of the factors are examined below.

1. Expert’s qualifications and experiences

The most prominent factor is the expert’s qualifications. “Qualifications”, as explained by the Court of Appeal, refers not to an expert’s “professional titles” but instead refers more generally to the expert’s “knowledge and familiarity”.9 While it is generally true that actual experience lends more weight to an expert testimony than mere paper qualifications, the High Court has qualified this by stating in obiter that this was “not an inevitable rule of thumb”.10

The relevance of practical experience to the subject matter of the case is considered down to a micro-level: the court has differentiated between experts with clinical experience in cancer diagnosis and experts with clinical experience in cancer treatment,11 and between experts in the treatment of drug addicts and experts in recognizing signs of drug addiction.12

Other factors that affect the weight given to an expert testimony are his experience doing research relevant to the case at hand,13 and his experience practising in the Singapore context.14 That a medical expert witness has experience treating one of the parties involved also lends authority to his testimony, since he would be more familiar with that party’s condition(s); however, his familiarity and personal relationship with the party raises clear possibilities of bias that must be dealt with.15

2. Impartiality of expert witness

The testimony of even the most qualified expert will not pass muster if it is tainted by bias. Hired guns fighting for the parties that called (and paid) them can hardly be relied on to provide accurate testimony. The influence of bias is great in practice due to monetary incentives being available, the priming of experts to be a part of the legal team, and the lack of safeguards against errant experts trying to manipulate facts to support a biased opinion.16

Although expert witnesses are appointed by parties themselves, their ultimate duty is always to the court.17 They cannot become mercenaries for hire, bending the facts for the highest bidder. Expert witness bias is especially dangerous because, by definition, expert witnesses have specialised expertise that the judge does not; an errant expert could easily mislead the judge and dictate the outcome. Therefore, judges must remain alive to the dangers of expert witness bias. Given the high stakes, judges impose only a low threshold to disqualify a biased expert testimony, such that even “perceived partiality or inclination” on the expert’s part can suffice to disqualify him for bias.18

3. Alignment with factual evidence

The words of even the most illustrious expert have no weight if it does not comport with the facts. Although disagreement in expert opinions is so common as to be almost inevitable, expert opinions must remain based on the facts established by the court. Expert testimonies that contradict the facts often prove fatal to that side’s case.19 When faced with insufficient evidence or evidence that contradicts the point their side wants to prove, it would be better for the experts to concede “where they ha[ve] to”20 than have the credibility of their entire report doubted by the court.

Factual evidence can also be used as a weapon to knock down opposing experts’ testimonies. In Hii Chii Kok v Ooi Peng Jin London Lucien and another,21 since the plaintiff’s expert could not provide “objective clinical data to support his assertions”, the court strongly preferred the defendant’s experts, whose testimonies “convincingly” countered the plaintiff’s expert’s testimony “point-by-point”.

Finally, expert testimonies should be precise and specific. Sweeping generalisations and conjecture are frowned upon, even more so when they are unsupported by evidence22 or are in relation to matters outside the expert’s field of expertise.23

4. Internal consistency of testimony

Inconsistency in an expert’s testimony casts a long shadow over his credibility. The degree of internal consistency has been described as one of the “paramount” considerations that courts will consider when assessing such reports.24 Given that experts are meant to guide the court, accepting the evidence of a muddled and confused expert that would does little to assist the court would be inimical. Therefore, courts readily reject inconsistent expert reports or grant them less weight even if admitted. An example would be in Chua Thong Jiang Andrew v Yue Wai Mun and another25 where the expert’s quality was harshly criticized because of various self-contradictions in his oral testimony plus ambiguities and conflations in his expert report. The court issued a scathing dismissal of his report, describing it as an “illogical and unconvincing” explanation that was “completely off the mark”.

On the other hand, courts appreciate experts maintaining a high degree of internal consistency in their testimony. In Public Prosecutor v Tengku Jonaris Badlishah bin Tengku Abdul Hamid Thani,26 the court considered the prosecution’s expert’s testimony positively, describing the expert’s opinion as “consistent, impressive and able to stand up to objectivity”. It should be noted, however, that a dogmatic expert who refuses to change his view even in the face of overwhelming evidence to the contrary is not necessarily preferable to a reasonable expert who concedes in such situations. Experts need not defend their point to the death for fear of sounding inconsistent: courts understand and appreciate an expert changing his view to consider and account for shortcomings in his side’s case. In Khek Ching Ching v SBS Transit Ltd,27 the court noted that under “withering” cross-examination, the plaintiff’s expert had conceded that he was unable to confirm with complete certainty the causation of the plaintiff’s injury. Because he had continued to maintain his position while still conceded where he had to, the court commended him as a “generally good” expert witness that had testified “professionally”, and noted that he had been “of assistance to the court”.

5. Expert’s methodology

Although courts are loath to put themselves into the expert’s shoes, an expert report derived using objectively flawed methodology will still be dismissed. It should be noted that an expert’s level of qualification is a separate and distinct factor from the quality of his methodology (although one would hope that the former would lead to the latter). Ong Pang Siew v Public Prosecutor28 is the main case where this factor has been relevant. In that case, where the accused pleaded the defence of diminished responsibility, the court harshly criticized the prosecution witness for his poor investigative methodology29 when writing his report. The defence witness’ “undoubtedly more comprehensive” methodology meant that his report turned the tide, and led the court to allow the appeal.

6. Expert pushing his/her own case theory

While it is natural for experts to form case theories from prolonged exposure to a case, it is prudent for experts to remain objective in their testimonies and not venture into interpreting facts. Once experts accept the responsibility of testifying, they must resist this temptation and stay impartial to the facts. However, this is easier said than done.

In Eu Lim Hoklai v Public Prosecutor,30 the Court of Appeal explicitly pointed out the Prosecution witness’ “over-enthusiastic allegiance” to her own case theory, and how, in her “absolute certainty” that it was correct, she had overlooked its “inherent improbabilities” and “uncertainty in the evidence”.31 The failure of the Prosecution’s “most important” witness in this important regard defeated the Prosecution’s case.32 Advocacy must ultimately be left to the lawyers, and the experts should keep within their own field.

C. Conclusion

As explained in the introduction, the exception of admitting expert witness testimony was necessitated by the increasing complexity of legal disputes. In the years since, as the sight of experts in courtrooms became commonplace, rules in this area appeared and grew. Today, much of the law on the admissibility of expert’s opinion is governed largely by Section 47 of the Evidence Act and interpretative cases, while the weight to be accorded to admitted evidence is a matter expounded on by case law.

Judges rely on experts to guide them through specialised fields of expertise, to assist them to reach justice, fairness, and truth. Thus, when searching for expert guidance, judges are just like the rest of us: they look for persons with impartiality, experience, clarity, and intellectual honesty. Such paragons of virtue may be hard to find, but there is hardly an alternative. The second part of this series will examine the trade-offs and such issues in greater depth.

[1] This has been established in a number of American studies. See Andrew W Jurs, “Expert Prevalence, Persuasion, and Price: What Trial Participants Really Think about Experts” (2016) 91 Ind LJ 353, which records that physicians make up the majority of experts at 37.5%; and Champagne et al, “An Empirical Examination of the Use of Expert Witnesses in American Courts” (1991) 31:4 Jurimetrics J 375, which observed that most experts were physicians (48%), and experts were mainly used in physical injury cases, and Samuel R Gross, “Don’t Try: Civil Jury Verdicts in a System Geared to Settlement” (1996) 44 UCLA L Rev 1, which observed that medical experts make up the majority of experts.

[2] Tal Golan, “The History of Scientific Expert Testimony in the English Courtroom” (1999) 12:1 Science in Context 7 at 9.

[3] Evidence Act (Cap 97, 2012 Rev Ed Sing, s 47(1).

[4] 293 F 1013 (DC Cir 1923).

[5] 509 US 579 (1993).

[6] Supra note 3 at s 47(2).

[7] Fok Chia Siong v Public Prosecutor [1999] SGCA 5 and Wong Swee Chin v PP [1981] 1 MLJ 212.

[8] Saeng-Un Udom v Public Prosecutor [2001] 2 SLR(R) 1; [2001] SGCA 38 at [26].

[9] Muhammad Jefrry v Public Prosecutor [1996] 2 SLR(R) 738; [1996] SGCA 44 [Jefrry] at [107].

[10] Sakthivel Punithavathi v Public Prosecutor [2007] 2 SLR(R) 983; [2007] SGHC 54 [Sakthivel Punithavathi] at [75].

[11] Noor Azlin Bte Abdul Rahman v Changi General Hospital Pte Ltd and others [2018] SGHC 35 (“Noor Azlin”) at [63].

[12] Jefrry, supra note 9 at [90]-[91].

[13] Supra note 11 at [23].

[14] Ibid at [63].

[15] Tan Teck Boon v Lee Gim Siong and others [2011] SGHC 76 at [7]; AOD, a minor suing by the litigation representative v AOE [2014] SGHCR 21 at [63].

[16] Jeffery D Pinsler, “Expert’s Duty to be truthful in light of the Rules of Court” (2004) 16 SAcLJ 407.

[17] Rules of Court (Cap 322, R 5, 2014 Rev Ed Sing), O 40A, r 2.

[18] Public Prosecutor v Thangaraju Sarukesi [2007] SGMC 7 at [71].

[19] See generally Sheila Leow Seu Moi v Public Prosecutor [2001] SGDC 376 [Sheila Leow]; Yeo Henry (executor and trustee of the estate of Ng Lay Hua, deceased) v Yeo Charles and others [2016] SGHC 220 at [63]-[67], [89], and [91]; Eu Lim Hoklai v Public Prosecutor [2011] 3 SLR 167; [2011] SGCA 16 [Eu Lim Hoklai] at [58], and Public Prosecutor v Tong Lai Chun [2003] SGMC 7 at [183].

[20] Khek Ching Ching v SBS Transit Ltd [2010] SGDC 220 at [95].

[21] [2016] SGHC 21.

[22] Sheila Leow, supra note 22 at [118]-[119].

[23] Eu Lim Hoklai, supra note 22 at [58].

[24] Sakthivel Punithavathi, supra note 10 at [75].

[25] [2015] SGHC 119.

[26] [1998] SGHC 401.

[27] [2010] SGDC 220.

[28] [2011] 1 SLR 606; [2010] SGCA 37.

[29] Firstly, the witness had failed to interview people who had recently contacted the accused person (thus breaching the diagnostic guidelines in the DSM-IV-TR, a reputed psychiatric manual). Secondly, he had also failed to investigate what the court considered to be relevant considerations, viz. the accused person’s changing jobs three times in the 18 months before committing the crime and his diabetes, which increased the risk of depression. Thirdly, he had interviewed the accused person in Mandarin even though he knew that the latter was more comfortable in Hokkien. The court thus condemned his methodology as an “unsatisfactory” one that “fell short of the requisite standard prescribed under the DSM-IV-TR”, especially since he, being the prosecution witness, would have much more available resources. Because of this, his testimony was held to be “less convincing” than that of the defence witness, who not only interviewed the accused in Hokkien, but also interviewed the accused person’s family members and the persons close to him.

[30] Eu Lim Hoklai, supra note 22.

[31] Eu Lim Hoklai, supra note 22 at [56]-[57].

[32] Eu Lim Hoklai, supra note 22 at [52] and [59].

The PDF version of this article is available for download here.

From Tragedy to Statistic: How Big Data has Changed the Practice of Law

by Bryont Chin

Data is information, and information never stops growing. In 2012, 2.5 exabytes1 of data were generated every single day.2 90% of the data in the world today has been created in the past two years.3 In Singapore, there is currently scant regulation pertaining to cybersecurity and data use. The Personal Data Protection Act4 and the Computer Misuse and Cybersecurity Act5 are the Legislature’s responses to these issues. These are mainly focused on preventing and penalizing cybercrime, especially intrusions into important government and private networks. However, while hacking is undoubtedly a perennial concern, in recent years many have asked another important question: how should the law respond to the increasing importance of big data and data analytics?

The term “big data” has been variously defined, but it centrally refers to “extremely large data sets that may be analysed computationally to reveal patterns, trends, and associations, especially relating to human behaviour and interactions”.6 Multinational companies and governments can collect these data sets, analysing them to generate insights which cannot typically be gleaned through traditional data analysis. Data collection, storage, and analysis is a field that is growing very important very quickly: according to International Data Corporation, a market intelligence and analytics firm, worldwide revenues for big data and business analytics will grow from $130.1 billion in 2016 to more than $203 billion in 2020.7


The meteoric rise in importance of this field has smashed existing practices in law firms. Legal practice is one of the most information-heavy industries, with the huge volume of precedent cases, regulations, case analyses, and legal commentaries. It used to be common to see armies of lawyers and paralegals sifting through information as part of due diligence. For the discovery process in United States v. CBS Inc.,8 the studios examined six million documents for more than $2.2 million—much of it going to lawyers and paralegals who worked for months at high hourly rates.9 But that was in 1978. Today, thanks to advances in artificial intelligence, “e-discovery” software can analyse documents in a fraction of the time, for a fraction of the cost. The Californian data analytics firm Blackstone Discovery has software that can analyse 1.5 million documents for less than $100,000, less than a fifth of what it would have cost thirty years ago.

The possibilities of data analytics for lawyers go beyond just search engines; even something as basic as the pricing of legal services has been completely changed. Clients and lawyers now have access to huge databases about prices that firms charge across the jurisdiction. The TyMetrix LegalView service continuously aggregates tens of billions of dollars’ worth of legal invoices, allowing law firms to choose the best position for themselves: an accessible low-cost provider or a high-end premium law firm.10 Another firm, Sky Analytics, offers companies a “Right Rate Advisor” tool, which assesses an external lawyer from many aspects to advise companies whether to accept or reject his fees.11 Over the years, a common complaint levelled at lawyers is the opacity of their fee structures and the resultant uncertainty. With a huge amount of data now available about legal fees, data analysis systems like TyMetrix LegalView and Sky Analytics’ “Right Rate Advisor” can make legal fees more transparent, making legal services more accessible for all.


However, arguably the most important use of data analytics is in the criminal law. Algorithms can now piece together information from a myriad of sources – police reports, arrest statistics, surveillance camera footage, and other information generated by the police – to better understand crime activity in a particular area and, more importantly, where criminals are likely to strike next. Based on this “predictive policing” system, the police can better deploy their resources to areas that are more prone to crime, and can respond faster and more effectively when someone breaks the law. One of the most ambitious predictive policing systems in the world is China’s “Police Cloud” system. Government databases scoop up everything from addresses, to medical history, supermarket membership, and delivery records. This information is linked to each citizen’s unique identification number, and is used by security bureau authorities to look for patterns in an individual’s behaviour. These databases are massive: for instance, police in Jiangsu, China have amassed 780 million data points on its citizens,12 collecting records of citizen’s incomes, navigation data, and their purchases from major e-commerce companies, among other things.13 In Shandong, China, the police can access patient records,14 names and causes of petitioners and political troublemakers,15 and social media usernames. With the Police Cloud, even the most intimate parts of a citizen’s life are open to the government.

The potential for abuse is obvious. In 2015, the Office of the Central Committee of the Chinese Communist Party announced their intention to embrace technology like the Police Cloud to achieve “social stability”. China’s Ministry of Public Security designed the Police Cloud system to surveil seven categories of “focus personnel”, including petitioners, those who “undermine stability”, and people “involved with terrorism”.16 Such vague definitions mean that essentially anyone could be designated a threat and placed under surveillance.

Chinese citizens do not have the right to be notified when placed under surveillance and have no legal avenues for contesting it.17 At present, China has no privacy or data protection law protecting personal data from misuse. The police are under no obligation to obtain a court order to conduct surveillance, or provide any evidence that the people whose data they are collecting from are associated with or involved in criminal activity. There are essentially no effective privacy protections against government surveillance, giving the Chinese police nearly unchecked power.

This is especially alarming if one remembers that predictive policing algorithms are not, and never will be, perfect. Predictive policing systems can only make predictions based on past data, which may not reflect actual risk patterns. Erroneous data will also result in erroneous predictions. A California woman recently won a civil rights lawsuit18 against the San Francisco Police Department after a number-plate reader misidentified hers as a stolen car and she was held at gunpoint by officers, forced to her knees, and detained for 20 minutes.

Especially dangerous is the very real possibility of bias in the input data or the man-made algorithms, causing bias in the predictions. The LAPD has seen a “feedback loop” in its PredPol system sparked by skewed input data.19 A racial bias in the existing crime statistics made the algorithm direct officers to certain neighbourhoods – typically those with many racial minorities – regardless of the true crime rate in that area. Errors and bias in data will inevitably survive in the resulting predictions. Authorities would do well to be cautious in relying too much on predictive policing systems.

That said, predictive policing’s short track record seems promising. Chicago’s 7th District Police reported that shootings in that district dropped 39% from January to July 2017 compared to the same period last year.20 The murder rate also dipped 33% during that period, while the murder rate in the city as a whole rose.21 Predictive policing systems have also beaten human analysts in other real-world trials.22 While the many inherent shortfalls of these systems must be acknowledged, and applications of these systems must take these failures into account, predictive policing is clearly a technology with great potential.


Apart from criticisms of the data analysis systems, data collection on such a scale also raises many legitimate privacy concerns. If GPS data shows Alice was at a hotel at 5 o’clock on Tuesday, and Bob was at the same hotel at the same time, it can be inferred that they might have been together. Further inferences can be drawn from conversation logs between them, if any. Therein lies the core of big data analysis: to reach conclusions that can be drawn through the correlation of many data points, which could not have been drawn from the data points themselves. If these data-sets are from public sources, does the individual have a right to privacy in the new information revealed through analysis? In United States v Maynard,23 the District of Columbia Circuit held that although the appellant’s individual journeys on public roads were public information, since the compilation of data on these journeys would not have been reasonably expected, the appellant’s behaviour patterns revealed through analysis of all of these trips together remain private.

How, then, are the inferences drawn from big data to be kept private? Data-sets are usually anonymized before use to protect the privacy of the individuals that the data was collected from. Anonymization is done through deletion of personally identifiable information (“PII”), or obfuscation thereof (for example, by changing a postcode from 1234567 to 123**). Top government agencies and leading technology companies have embraced anonymization to protect privacy rights: the US Department of Defence has recommended anonymization “whenever practicable”,24 and Google has said that its anonymization techniques can make identification “very unlikely”.25 Prominent legal scholars also share this faith in anonymization,26 and claim that anonymization can make data reidentification “impossible”.27

This faith is misguided. Unfortunately, data reidentification is easier than most would think. If all PII is removed from a data-set, there will be nothing left, since every piece of data is potentially useful in identifying an individual. Therefore, for data, complete privacy means zero utility. For a data-set to have any use at all, some PII must be retained. The widespread faith in anonymization is based on the belief that it is possible to remove enough PII to prevent identification and still retain enough to keep the data-set useful. However, very little PII is actually necessary for deanonymization and thus identification. It has been shown that 87.1% of people in the US can be uniquely identified by their combined five-digit ZIP code, birth date, and sex.28 53% of American citizens are uniquely identified by their city of residence, birth date, and sex.29

Using just three easily obtainable pieces of information, the vast majority of people can be identified using “anonymized” data. Privacy, in the age of big data, is a much more elusive ideal than previously thought. While it would be asking too much for legislators to come up with rules that could prevent any subsequent deanonymization, legislators must at the very least abandon the idea that removing PII is sufficient protection of privacy in today’s security climate. Since this assumption is the foundation to nearly all privacy laws in use today, a paradigm shift is necessary for legislators and industry leaders in this field.


The law is often slow to respond to societal change. Legislatures must mire themselves in debate before promulgating laws far overdue by the time they are passed. The courts, while more flexible, are still reactive rather than proactive. While both bodies stagnate, the total amount of information grows, and private companies and states worldwide are responding to this wealth of information with increasing urgency. In particular, legal practice has been affected: the availability of these huge amounts of data and the analysis has changed case analysis, pricing of legal services, and even the generation of evidence. Police departments worldwide now routinely draw on predictions based on huge data-sets collected from surveillance networks and private companies. Proponents of such policing systems posit this helps the authorities respond faster and more effectively to changing crime trends; critics argue that this breaches the citizen’s right to privacy and gives the authorities untrammelled power to a dystopian degree. Underlying these are the individual’s privacy rights and the unfortunate reality that it is harder to protect these rights than previously thought. Whatever the stance taken, we cannot afford to ignore these issues. A single death is a tragedy but a million deaths a statistic; the countless records of crimes and punishments that form the law have many lessons to teach us, but only if we decide to listen.

[1] Equivalent to 2.5 billion gigabytes, or 2.5 x 1018 bytes.

[2] Ralph Jacobson, “2.5 quintillion bytes of data created every day. How does CPG & Retail manage it?” (24 April 2013), IBM Consumer Products Industry Blog, online: <>.

[3] Ibid.

[4] (No 26 of 2012).

[5] (Cap 50A, 2007 Rev Ed Sing).

[6] From The Oxford English Dictionary, 2nd Ed, sub verbo “big data”.

[7] This is a compound growth rate of 11.7% per annum. See Gil Press, “6 Predictions For The $203 Billion Big Data Analytics Market”, Forbes (20 January 2017), online: <>

[8] 459 F Supp 832 (CD Cal 1978).

[9] John Markoff, “Armies of Expensive Lawyers, Replaced by Cheaper Software”, The New York Times (4 March 2011), online: <>.

[10] Joe Dysart, “How lawyers are mining the information mother lode for pricing, practice tips and predictions”,  online: (May 2013) ABA Journal <

[11] Ibid. Sky Analytics has revealed that the Right Rate Advisor refers to, among other factors, the external lawyer’s years of experience, his or her position in the firm, the size of the firm, and the cost of living where the lawyer is based.

[12] What do China’s police collect on citizens in order to predict crime? Everything, online: Quartz <>.

[13] Echo Huang, “China: Police ‘Big Data’ Systems Violate Privacy, Target Dissent”, Human Rights Watch (20 November 2017), online: <>.

[14] Including names and illnesses.

[15] Ibid. A tender document from Tianjin boasted that its Police Cloud system could monitor “petitioners who are extremely [persistent]” and “Uyghurs from South Xinjiang”. It could even pinpoint their residences and track their movements on maps.

[16] Ibid.

[17] Ibid.

[18] Green v City and County of San Francisco, 751 F.3d 1039 (2014)

[19] Danielle Ensign et al, “Runaway Feedback Loops in Predictive Policing” (2017) arXiv:1706.09847v2 [cs.CY]

[20] Juliet van Wageren, “Cities Give Predictive Policing a Second Look”, Slate Tech Magazine (12 December 2017), online: <>.

[21] Ibid.

[22] During a four-month trial in Kent, London, 8.5% of all street crime occurred within and next to the areas the PredPol system designated as high crime areas, predictions from police analysts scored only 5%. An earlier trial in Los Angeles saw the machine score 6% compared with human analysts’ 3%. See “Don’t even think about it”, The Economist (20 July 2013), online: <>.

[23] 615 F.3d 544.

[24] Technology and Privacy Advisory Committee, Safeguarding Privacy in the Fight Against Terrorism (United States of America: Technology and Privacy Advisory Committee, 2004) at 50 (Recommendation 2.2). The document is available at:

[25] Chris Soghoian, “Debunking Google's log anonymization propaganda”, CNET (11 September 2008), online: <http://news.cnet.com8301-13 739_3-10038963-46.html>

[26] Ira S. Rubinstein et al, “Data Mining and Internet Profiling: Emerging Regulatory and Technological Approaches” (2008) 75 U Chi L Rev 261, at 266 and 268

[27] Barbara J. Evans, “Congress' New Infrastructural Model of Medical Privacy” (2009) 84 Notre Dame L Rev 585, at 619-20

[28] L. Sweeney, “Simple Demographics Often Identify People Uniquely” (2000) Carnegie Mellon University, Data Privacy Working Paper 3.

[29] Ibid.

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