（接上文）

《证据法》下册个别段节 

1. 采纳与否的考虑之一：专家证据必须是针对有公信、有定论与被承认的专业知识或特殊经验 

这是针对是否批准与采纳专家证据的第一关。英国判决中对此要求有许多不 同说法如“reliable body of knowledge or experience”、“recognised scientific discipline”、“established body of knowledge”等等。显然，这是为了防范伪科学 （fake/junk science）或假专家（false expertise）。除了审理法官要防范，没有法 律训练的陪审员更是要被保护，不让他们受到误导、迷惑与影响。意见（opinion） 往往难分真假优劣，而一般人士又特别喜欢听意见，特别是来自带有“专家”名 称的意见。所以，法官必须作为“守门员”（gate-keeping）严格保护陪审团，而 方法就是通过采纳与否的决定。 

1.1 有这个要求的原因 

有这要求的原因是如果没有一个已经有大量研究（research）与/或方法论 （methodology）的科题或有了一些定论的说法，即使不是“伪科学”，也难以判 断证人相比其他人是否“真专家”与说的话可信赖（reliable）。法院也无法从双 方专家证人提供不同的个人意见分析哪一位比较可靠与可以信赖，或甚至是都不 可信（因为是伪科学），并在判决中说是根据什么理由作出这样的决定。相反， 如果提供的大量资料显示一方诉讼方专家证人主张的意见在该专业笵畴有更广 泛与持久的支持。而另一方的专家意见虽然有过这一说法，但被批评与说不通， 也有无法解释的地方。这一来，审理法官就很容易有根有据地作出决定了。 

这在 Kennedy v. Cordia (Services) LLP (2016) UKSC 6 的最高院先例说： 

“In many cases where the subject matter of the proposed expert evidence is within a recognised scientific discipline, it will be easy for the court to be satisfied about the reliability of the relevant body of knowledge. There is more difficulty where the science or body of knowledge is not widely recognised. … an orbiter dictum in Lord Eassie’s opinion in Mearns v. Smedvig Ltd 1999 SC 243 in support of their proposition that: 

‘ A party seeking to lead a witness with purported knowledge or experience out with generally recognised fields would need to set up by investigation and evidence not only the qualifications and expertise of the individual skilled witness, but the methodology and validity of that field of knowledge or science.’ 

We agree with that proposition, which is supported in Scotland and in other 

jurisdictions by the court’s refusal to accept the evidence of an expert whose methodology is not based on any established body of knowledge. Thus, in Young v. HM Advocate 2014 SLT 21, the High Court refused to admit evidence of ‘case linkage analysis’ because it was the subject of only relatively recent academic research and a methodology which was not yet sufficiently developed that it could be treated as reliable. See also, for example, R. V. Gilfoyle (2001) 2 Cr App R 5, in which the English Court of Appeal (Criminal Division) refused to admit expert evidence on ‘psychological autopsy’ for several reasons, including that the expert had not embarked on the exercise in question before and also that there were no criteria by reference to which the court could test the quality of his opinions and no substantial body of academic writing approving his methodology. …” 

上诉庭的 R. v. Dawson and Hamburger (2004) EWCA Crim 1344 刑事先例涉 及“唇语证据”（Lip-reading evidence）是否足够公信、有定论与承认的认识与 经验，与这种专家意见证据是否可信（reliable）的争议。被告的专家证人认为这 种专家证据本质上是不可靠，也没有定论，不是受到承认的专业知识。所以，法 院不应该采纳为专家证据。上诉庭说：“The judge （指一审法官） … rejected the defence submission that there was no sufficiently well established field of lip reading expertise for it to be accepted as reliable body of knowledge or experience. … Professor Campbell （被告专家证人） , … considered all lip reading intrinsically unreliable and it could not be used in court.” 

虽然唇语有很多变数，包括像小孩与成年人、从旁与面对面唇语、嘴唇变形 或脸上没有表情等等，都会带来困难与准确度差异。但法院最后还是认为专业好 的专家证人在条件配合的情况下准确度会高达 80%并采纳了专家意见证据。 

在较早前的 R. v Stockwell (1993) 97 Cr.App.R 260 先例，涉及银行抢劫。由于强盗伪装，加上被告在他被抓捕前蓄须，所以原告（政府检察院）加了面部映 射（Facial Mapping）证据，即监控视频中的人脸是否能与被告的面部对应。这受 到被告反对，认为这是新科技（breaking new ground），再加上专家证人是帮不 了陪审员，所以不应采纳。上诉庭不同意去排斥新科技，只要它有适当的基础或 定论，说：“One should not set one’s face again fresh developments, provided they have a proper foundation.”而专家证据是否会帮助陪审员理解有关事实是由一审 法官在不同情况下决定，说： 

“Where, for example, there is a clear photograph and no suggestion that the subject has changed his appearance, a jury could usually reach a conclusion without help. Where, as here, however, it is admitted that the appellant had grown a beard shortly before his arrest, and it is suggested further that the robber may have been wearing clear spectacles and a wig for disguise, a comparison of the photograph and defendant may not be straightforward. In such circumstances we can see no reason why expert evidence, if it can provide the jury with information and assistance they would otherwise lack, should not be given. In each case it must be for the judge to decide whether the issue is one on which the jury could be assisted by expert evidence, and 

whether the expert tendered bras the expertise to provide such evidence.” 

在之后不久的 R. v. Robert Lee Clarke (1995) 2 Cr.App.R. 425 上诉庭先例，也是银行抢劫。由于在场证人无法在辨认嫌疑人（Identification Parade）的过程中 认出嫌疑犯，等于没有目击证人（eye witness），所以只能依赖银行监控拍下的 强盗照片作为物证（Real Evidence），并以专家证据的分析与意见去帮助陪审团。 这也是受到被告的反对，包括通过视频叠加的面部映射（facial mapping by way of video superimposition）不可信，特别是在没有目击证人的情况下去定罪是不妥。 上诉庭的 Steyn 大法官说： 

“It is essential that our criminal justice system should take into account of modern methods of crime detection. It is no surprise, therefore, that tape recordings, photographs and films are regularly placed before juries. Sometimes that is done without expert evidence, but, of course, if that real evidence is not sufficiently intelligible to the jury without expert evidence, it has always been accepted that it is possible not place before the jury the opinion of an expert in order to assist them in their interpretation of the real evidence. … 

We are far from saying that such evidence may not be flawed. It is, of course, essential that expert evidence, going to the issues of identity, should be carefully scrutinised. Such evidence could be flawed. It could be flawed just as much as the evidence of a fingerprint expert could be flawed. But it does not seem to us that there is any objection in principle.” 

另是在 Pride Valley Foods v. Hall & Partners (2000) EWHC Technology 106 先 例，涉及工厂建设的项目管理人（Project Manager）是否疏忽导致失火，焚毁工 厂。高院的 Toulmin 大法官认为针对项目管理人是否疏忽的专家证据对法院没有 什么可以帮助。因为项目管理人没有一个特许或专业协会，也不是一个容易被辨 认的专业（recognisable profession）。项目管理人的职责在不同的项目中也有不同。 该先例涉及的上百页专家报告中有不少都是针对在同样的情况下，他会怎样做或 批评被告的做法。但这应是法院而不是专家证人的工作，不应被采纳。 

1.2 新科技/新发展 

所以，如果是太早期的新科技或新发展、尚未有定论与参与人数不多的社会 或自然科学/理论，就会有问题了。例如，笔者记得或听说在早期的基因鉴定、测 谎机、笔迹鉴定等都曾经有过很大的争议性。说到底，这实是有关证据价值 （probative value）。一种尚在试验中连科学界本身也没有定论的新科技，因为太 不肯定，会是难以被法院接受。从试验阶段（experimental stage）到成熟阶段的 一段时间，所谓的“神秘范围”（Twilight Zone）是什么时候终止可以说是说不清。 看来美国作为科技与法律强国，在这方面的先例不少，因为像专利等争议也经常 会涉及专家证据。在早期的 Frye v. United States (1923) 293 F. 1013 先例，针对这 方面说： 

“Just when a scientific principle crosses the line between the experimental and demonstrable stages is difficulty to define. Somewhere in this twilight zone, the evidential force of the principle must be recognised, and while the courts will go a long way in admitting expert testimony deduced from a well-recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the field in which it belongs.” 

以上是说新科学原理在什么时候从实验阶段变为可论证阶段很难说死。在这 神秘范围，总有一天法院可以承认这科学原理有证据价值。法院会慢慢接受由被 广泛被承认的科学理论或发现演绎而来的专家证据，而该科学理论或发现一定先 要在本行业（如医学界、天文学界、鉴证学界等）已被广泛接受/承认。 

之后，美国的 United States v. Baller (1975) 519 Fed.2d. 463 先例把这方面的 准则说得更清楚，如下： 

1. “There must be a demonstrable, objective procedure for reading the opinion1;  
2. There must exist ‘qualified persons’ who can either duplicate the result or criticize the means by which it was reached, drawing their own conclusions from the underlying facts2;  
3. Deciding whether these conditions have been met is usually within the discretion of the trial judge3; 
4. absolute certainty of result or unanimity of scientific opinion is not required for admissibility4; 
5. Unless an exaggerated popular opinion of the accuracy of a particular technique makes its use prejudicial or likely to mislead the jury, it is better to admit relevant scientific evidence in the same manner as other expert testimony and allow its weight to be attached by cross-examination and refutation.5” 

英国也估计是同样法律地位：R. v. Turner (1975) 1 QB 834 先例。而且有一宗

1 一定要有一个可以论证与可客观衡量的程序去考虑这个意见。 

2 一定要有合资格与适合的人士，可以重复这方法并得出同样结果或可以抨击这些方法与结果， 通过同样的基本事实得出他们不同的结论。 

3 一审法官有裁量权决定是否满足了这些条件。

4 这科学理论不需要是绝对肯定（世界上本来就难有绝对）或有关的科学界一致同意（世界上总 会有唱反调的人）才有证据价值被采纳。 

5 除非一些夸大与不准确的意见会误导陪审团带来坏处多过好处，最好或较安全的做法还是批准 与采纳这些专家证据。然后在开庭审理听了双方代表律师的交叉盘问与反驳后，在证据分量的轻 重上调整。 

澳大利亚先例讲明依照 United States v. Baller 先例的准则：见 R. v. Gilmore (1977) 2 N.S.W.L.R. 935 先例。 

最后去总结说，新科技在尚未成熟的“神秘范围”的期间，原则上是应避免 采纳专家意见证据。除了新科技或新发展不肯定与不可信赖外，双方诉讼方的专 家证人自称是“专家”，但在该冷门专业也没有人不是专家。专家意见也只是各 说各的主观看法，没有其他有关书籍（更不说是有业界接受的权威书籍）或文章 去针对过，审理法官也就无法分析与客观衡量两位专家意见的“证据价值”，并 在判决中说得出理由支持最后的选择了。这一来，倒不如法官自己凭双方代表律 师的争辩中的解释决定。好的代表律师需要有本事能通过己方的专家顾问解说， 吸收专业性很强的事情，然后以简单与听得懂的语言解释到令外行的法官（或陪 审员/仲裁员）能够明白。 

1.3 近期先例显示了对这个要求收紧的趋势 

在近期的先例，显示了法院是严格的针对这方面，即使从表面看来专家证据 要针对的点好像是很专。这可介绍 Vilca v. Xstrata Limited (2017) EWHC Civ. 136 先例，案情涉及在 2012 年南美秘鲁的一个由被告公司（是一家跨国的矿业公司） 拥有的铜矿场，矿工发生抗议，导致出动警察镇压并造成伤亡（2 人死亡与多人 受伤）的事件。之后有 20 个受害矿工在英国向被告提起索赔，指称被告指使秘 鲁警察暴力镇压，违反了被告自己公开采纳的联合国“安全与人权的自愿原则” （Voluntary Principles on Security and Human Rights）下要求矿业与石油工业（Oil and Mining industries）对待与保护作为雇员的矿工的良好标准（good practice）。为了针对这方面的争议，被告在案件管理会议的时候申请针对这一个自愿原则 （可简称 VP）引入专家证据，并说明委任的 Freeman 先生是一位十分资深的专 家证人，如曾在美国国务院劳工与人权部门任职副秘书长，并与英国外交部一并 在国际推动这一个自愿原则。但原告大力反对，理由包括这套 VP 只代表一些人 类的“希望”（aspirations），不是“行业标准”（industry standard），也没有一套规 管机构订立的守则（rules of conduct set by a regulatory body）等，所以不存在什 么专家证据。Freeman 先生顶多说凭他个人的经验，国际上其他的矿场会做什么 或不会做什么。反正不是专家意见而只是他个人意见，也不是针对一些已经有了 公信、定论与受到承认的行为准则。 

在一审法院，Foskett 大法官同意原告的说法，拒绝采纳与批准专家证据，并 跟从了不久前的一个也是有关非洲坦桑尼亚金矿场的同样事故的案例。在该 Kesabo v. African Barrick Gold (2014) EWHC 4067 先例，原告想引入两位专家证 人：一位是 Warner 先生，据原告说是“矿场在冲突时的管理”（mining community engagement in situations of conflict）方面的专家；另是一位 White 先生，据原告 说是“在面对群众抗议与公众秩序的场合有丰富的管理与策划的经验” （significant operational command and planning experience in the area of policing of protest and public order）。 

但 Andrews 大法官拒绝了两位专家证人，针对 Warner 先生说： 

“… not an expert discipline which falls within the category recognised … as part of a body of knowledge or expertise which is sufficiently organised or recognised to be accepted as a reliable body of knowledge or experience … 

If and in so far as any evidence that Mr Warner is able to give could be relevant to the issues that have to be decided in this case, it would appear that it would derive from his knowledge of what, as a matter of fact, other mining companies may or may not do, and what standards they apply … However that would be purely factual evidence and is not a matter of expertise.” 

另针对 White 先生是说：“There is nothing before the court today in terms of evidence that suggests that a body of recognised opinion exists as to what are the appropriate steps to be taken in terms of policy a mine or dealing with public order issues arising in consequence of people trespassing in or near a mine. Thus there is no objectively ascertainable standard or consensus against which to judge the defendants’ behaviour.” 

Andrews 大法官也认为 White 先生想提供的所谓“专家证据”，本质上是说其 他人士或公司会在某些情况下会怎样做，这对法院是没有帮助。因为有经验的审 理法官完全可以根据认定的事实情况，决定到底做法上有没有疏忽与合理不合理， 不需要任何其他人给意见来帮助，说： 

 “An experienced trial judge is well able to determine questions of negligence against the appropriate matrix without the assistance of somebody coming in and saying what they would have done in a similar situation, or expressing a view as to whether what the Defendants actually did was reasonable, in the light of their experience in similar (or different) situations m which appears to be the high watermark of what one would be able to get from Mr White. … thus the subject-matter of Mr White’s putative opinion, so far as it is possible to discern anything about it, does not appear to be something on which expert evidence is permissible.” 

再回去 Villa v. Xstrata Limited 先例，Foskett 大法官说： 

“… Ms Fatima QC 

（原告代表大律师） contents, however, that the proposed evidence falls at the first hurdle in that it cannot properly be characterised as ‘expert’ evidence. … She submits, in the first instance, that this is not a situation in which there is a recognised expertise governed by recognised standards and rule of conduct capable of influencing the Court’s decision.  

… At all events, the question in the present case is whether there is a recognised standard of conduct for dealing with the kind of demonstration that occurred to be deduced from the VPs. … the issue to be addressed is very similar to that addressed by Andrews J in Kesabo v. African Barrick Gold (2014) EWHC 4067 (QB). In that case the claimants were pursuing claims for damages arising from injuries or deaths that 

occurred in or around a gold mine in Tanzania sustained, it was alleged, as a result of the use of unlawful and/or excessive force by private security forces and/or police at a mine operated by the defendants. … 

Ms Fatima says the same applies here. I agree. There may, one supposes, be an emerging consensus about what represents good practice in the kind of situation that arose in this case, but it would be impossible, certainly on th available evidence, to conclude that there was an established consensus.” 

1.4 英国立法的规定 

根据英国证据规则《Civil Evidence Act 1972》立法之 Section 3，对可被采纳 的专家证据有大同小异的说法： 

“in any case where the court accepts that there exists a recognized expertise governed by recognised standards and rules of conduct capable of influencing the court's decision on the issues which it has to decide.” 

1.5 美国立法的规定 

美国的联邦证据规则《US Federal Rules of Evidence》之 Rule 702 对采纳专 家证人/证据与否有针对，这也是在美国最高院在 Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 US 579 (1993)先例中作出指引后的修改。如果专家证人 的意见证据（opinion evidence）能满足以下要求是可被采纳： 

(1) 专家的科学（scientific）、技术（technical）与其他专业知识（other specialized knowledge）是可以帮助对争议事实作出判决/认定人士（即法官或陪 审团成员）更理解这些事实证据。 

(2) 专家证据有足够的事实或数据依据（the testimony is based on sufficient facts or data）。 

(3) 专家证据是通过可靠/可信赖的原则与方法（例如，人体内的血块是怎样 形成或怎样推算某特定市场的反应等等）得出的意见与结论（the testimony is the product of reliable principles and methods）。 

(4) 专家将这些原则与方法可靠/可信赖地适用在案件的事实（the expert has reliably applied the principles and methods to facts of the case）。 

可以说，Rule 702 要求专家证人必须对有关专门知识符合资格（the expert be qualified）；专家证据对法官或其他根据证据认定事实人士更精确了解特定事实的 证据有帮助（the testimony address a subject matter on which the fact-finder can be assisted by an expert）；专家证据可靠与可信赖；专家证据与案件的事实有关/配合 （the testimony 'fit' the facts of the case）。