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Demonstrative Evidence – Cognitive Overvaluing Search Truth

12 Nov Demonstrative Evidence – Cognitive Overvaluing Search Truth


Demonstrative Evidence – Cognitive Overvaluing Search Truth

People remember the pictures.

However, some pictures do not deserve to be remembered. Not in preference to more cogent evidence.

But it may not enhance the search for truth.

The search for truth is sacrosanct. Courts are vigilant to ensure that trials are not infected with bias that sways judgment and disables triers-of-fact from performing their function.

The thesis of this paper is that courts should be as vigilant to protect triers-of-fact from any evidence, including demonstrative, that potentially injects bias, induces error, sways judgment or otherwise prejudices the proper performance of judicial function.

There is a fine line between persuasion and distortion. Just as demonstrative evidence has the power to persuade, so too does it have the potential to cross the line and distort. In short, demonstrative evidence is not just another piece of evidence and should not be treated as such. It is more powerful. It has greater impact. It must accordingly be given special scrutiny in the manner of evidence involving novel science because it has novel science’s potential to distort fact-finding by distracting triers-of-fact from more cogent evidence. If the graphic photograph, vivid animated recreation or colourful chart are all that the trier-of-fact remembers, this memorable evidence may be accepted as truth when it is not.

The gatekeeper responsibility as regards demonstrative evidence must lie with judges. Advocates want to persuade. They seek a result that is favourable to their client. Advocates will present as persuasive a story as permitted by the trial judge and an unwary adversary. Indeed, it has been suggested in relation to closing argument that there is a need to restrain adversarial excess in closing argument that is the result of the advocate’s desire to win. This desire to win causes the advocate to attempt to “muddy the waters of decision”. Others counter that the advocate is not a seeker of truth but a creator of belief.[1] By whatever rationale, advocates cannot be expected to pass up an opportunity to persuade even if the result is to hamper rather than assist responsible decision-making.

Unlike advocates, judges are gatekeepers. Absent bias, ingrained or induced, they do not seek a particular result. Judges protect the process of truth-searching. They strive for impartiality.

As part of their responsibility to protect the trier-of-fact from that which induces bias or distorts truth-seeking, judges must protect triers-of-fact, including themselves, from giving undue weight to evidence simply because it is vivid and, hence, memorable.

Judges must not avoid the gatekeeper role by treating issues relating to demonstrative evidence as going only to weight to be assessed by the trier-of-fact. The trier’s ability to appropriately assess weight may be impaired by the vivid nature of the evidence in issue or by its more subtle, and hence undetectable, tendency to distort.

Some commentators and judges analyze the impact of demonstrative evidence solely in terms of its potential to inflame emotion and therefore induce bias. Others focus on the issues of relevance and reliability. The potential for demonstrative evidence to distort fact-finding by diminishing more cogent evidence, thus inducing inferential or cognitive error, has received less attention but is as great a concern.

We may be moving towards trials where every witness’ oral evidence is animated, recreated or subject to demonstration so as to increase its impact under the guise of increasing reliability or understandability as advocates increasingly use “compelling images and illustrations” that have greater impact and enhance the chance of victory.[2]

However, using demonstrative evidence to secure victory by distorting fact-finding goes too far and should be considered as illegitimate as an attempt to secure victory by appealing to prejudice. Each is nothing more than an attempt to render triers-of-fact unable to impartially perform their judicial function.

That contemporary attention spans are short is no excuse. Truth-seeking takes time. Triers-of-fact are quite capable of learning orally as well as visually if appropriate time is devoted to the task and notwithstanding that some are more easily persuaded when they are entertained by evidence that is illustrated, charted, animated or reenacted “into a neatly packaged, compressed and easily assimilated sight and sound bite”.[3]

As former Los Angeles prosecutor Vincent Bugliosi wrote in the context of criminal trials and television cameras: “A trial is a serious and solemn proceeding that determines whether a person’s liberty, and sometimes his life, should be taken away. Anything that interferes, or even has the slightest potential of interfering, with this determination should be automatically prohibited.”[4]

Civil litigants are surely entitled to the same procedural safeguard.

The Ontario Court of Appeal has ruled in relation to expert evidence that: “Judges who fail to properly perform their gatekeeper function as regards expert evidence run the risk of having their decision-making function usurped or severely eroded by ‘expert generalists’ who profess to know something about everything and are only too willing to provide the court with a ready-made solution for any contentious issue.”[5]

Just as “courts must be vigilant to guard against such impermissible evidence”[6], so too must courts be vigilant to guard against the distortion of fact-finding because of the artistry of the screenwriter, animator, filmmaker, photographer or illustrator.

We live in a visual age, but to recognize this is not necessarily to celebrate it in all contexts. As Adam Gopnik has written concerning Lincoln and Darwin:

“Most periods have a manner or style or form that’s primary to the way the people of the time organize their feelings about the world. Stephen Greenblatt has shown us how much Elizabethan England was a theatrical society, one in which the pageantry of public life, the ambiguous rituals of religion, even the horrific public executions, flowed in some way into a shared vision of the world as stage.

“The frontier America of Lincoln’s youth was first of all a rhetorical society, where the ability to speak in public, at length was central to social ambitions; giving a speech in 1838 in Illinois was the equivalent of putting on a play in 1598 in London, the thing you did into which everything else flowed. (We are, by turn – and a writer says it with sadness – essentially a society of image: a viral YouTube video, an advertising image, proliferates and sums up our desires; anyone who can’t play the image game has a hard time playing any public game at all.)”[7]

People really do remember the pictures. We are a society of image and advocates may seek to persuade by playing “the image game”. But even in the YouTube age, images must not be allowed to assume undue prominence when truth is at stake.

Method of Analysis

I propose to analyze this paper’s thesis by:

– recognizing that trials are a search for truth;

– contrasting neutrality with bias and recognizing that the sanctity of the search for truth is such that evidence that appeals to or induces bias is never permitted;

– defining “demonstrative evidence” as the term is used in this paper;

– expressing concern about the acknowledged power of vivid demonstrative evidence to diminish more cogent, but less vivid, evidence;

– describing the continuum of demonstrative evidence from innocuous to vivid and its corresponding “continuum of decreasing admissibility”, to quote an American commentator, and

– arguing that just as jurors are vulnerable to bias and also to cognitive error, so too are judges such that rulings concerning demonstrative evidence must be made before trial by other than the trial judge.

The Search for Truth

The ultimate goal of any trial is to seek and ascertain the truth.[8]

The goals of the law of evidence include assisting the search for truth, providing fairness as regards the trial process and preventing unfair bolstering of one party’s evidence.[9]

Advocates are increasingly resorting to demonstrative evidence in openings, evidence presentation and closings. Advocates may even seek to have demonstrative evidence filed as exhibits so that the evidence may be treated as “real evidence” to be “used by the jury in the jury room during deliberations”.[10] In this way, demonstrative evidence may continue to act as an “advocate” after counsel has completed final submissions.

The reasons for what has come to be widespread use of demonstrative evidence is that it has come to be considered as offering “stronger and more convincing proof” than oral evidence.[11]

However, although advocates may legitimately rejoice at the tremendous potential of demonstrative evidence to secure victory this does not mean that demonstrative evidence necessarily facilitates the search for truth. To the contrary, creativity and visual stimulation may distort fact-finding by diminishing the impact of more cogent, but less vivid, evidence. Certainly, the potential of demonstrative evidence to induce cognitive error in fact-finding needs further study before it may be safely said that demonstrative evidence may be used at trial “as a matter of everyday practice in our courts”.[12]


The Supreme Court of Canada has held that a system of justice, if it is to have the respect and confidence of its society, must ensure that trials are fair. Fair trials require that courts be held to the highest standards of impartiality. Indeed, the right to a trial before an impartial judge is of fundamental importance to our system of justice.[13]

Inducing bias at any stage of a trial renders it unfair.

“Impartiality” and “bias” were contrasted by the Supreme Court of Canada as follows:

“Impartiality can be described as a state of mind in which the adjudicator is disinterested in the outcome, and is open to persuasion by the evidence and submissions. In contrast, bias denotes a state of mind that is in some way predisposed to a particular result or that is closed with regard to particular issues.”[14]

Bias, so defined, is not limited to predisposition or predilection. Bias includes evidence at trial that would tend or may be regarded as tending to cause someone acting in a judicial capacity to decide a case otherwise than on the evidence.[15] The judicial officer becomes “biased”, in that the judicial officer now inclines “to one side”, her or his judgment is swayed and she or he has been rendered unable to exercize judicial functions impartially.[16]

The Advocate’s Role

As noted, advocates seek to persuade. Favourable evidence is called. Persuasive submissions are made. No responsible advocate seeks to inject bias into the process including inappropriate appeals to emotion. At the same time, advocates recognize that emotion may be a critical factor in the ultimate decision.

Indeed, it has been written that ninety percent of any decision is emotional.[17] The inference is that the effective advocate should seek, albeit subtly, to appeal to emotion.

Two Ontario Supreme Court Justices, Robert Reid and Richard Holland, described the advocate’s task as follows:

“to paint a picture that the court will buy. It is to use the best colours in a limited palette; to avoid off colours and bad images… counsel do not realize how subjective the process is, and how susceptible it is to the skill of the advocate… the practice of advocacy is the practice of persuasion and the task is not finished until the trial is complete, for no case is lost until judgment has been given.”[18]

Legitimate picture-painting is one thing. However, impartial, neutral adjudication becomes impossible when – at any stage of a trial – triers-of-fact and/or law become biased, induced to err or otherwise become “closed with regard to particular issues” by, for example, a successful appeal to emotion.[19] Such appeals cause a judicial officer to be unable to exercise his or her functions impartially in a particular case.[20]

Bias is not limited to favourable or unfavourable pre-trial disposition based on race, ethnicity, religion, or sexual preference (to cite just a few examples). Bias includes situations where the trier-of-fact acquires or comes to believe evidence that ought not to have been received. For example, in a criminal trial a juror’s mind that was initially open to persuasion may become closed to persuasion by relevant evidence because the trial judge failed to exclude evidence concerning an accused’s prior criminal activities. By such legally inadmissible evidence, jurors may become so “inflamed” that a guilty verdict is returned regardless of the relevant and legally admissible facts of the case being tried. [21] Thus, courts are empowered to “categorically excluding certain evidence because of its inherently prejudicial nature, such as the admission of character evidence to prove action in conformity with such character, and the admission of the alleged victim’s past sexual behaviour in a rape case.”[22]

It is accepted, therefore, that counsel are prohibited from inflaming or prejudicing a jury. An American author has noted that it is considered prosecutorial misconduct to make direct inflammatory appeals to the jury, to ask the jurors to ignore their proper function of determining if guilt has been proven beyond a reasonable doubt, make arguments calculated to appeal to the prejudices of the jury and, make arguments that would divert the jury from its duty to decide the case on the evidence. To cite the most obvious example, appeals to racial passion can distort the search for truth and drastically affect a juror’s impartiality.[23]

On the same rationale, plaintiff’s counsel was severely criticized by the Ontario Court of Appeal in Landolfi v. Fargione[24] for exceeding the “important limits on the bounds of a closing jury address” because counsel’s comments:

“improperly invited the jury to decide the case on the basis of an extraneous and irrelevant consideration – the credibility of defence counsel – rather than on the strength of the evidence adduced at trial… the comments risked diverting the jury’s attention away from its true task, namely, an objective evaluation of the relevant issues, the positions of the parties in relation to those issues, and the evidence pertaining to those issues.”

Plaintiff’s counsel was criticized for her Opening to the jury in Chilton v. Bell Estate[25]. Counsel began by using words such as “horror, surprise and helplessness”. The trial judge ruled that these words would “excite emotion at the expense of reason”. The trial judge also criticized plaintiff’s counsel for attempting to cast the defendant as a villain such that “fairness and justice are equated to a result favourable to the plaintiff”, dealing in detail with evidence the plaintiff was not going to call, incorporating diagrams and photographs without prior court permission and without assurance the visual aids could be introduced into evidence and concluding with a “full-blown liability argument”.

Justice Donnelly ruled that “the harm done could not effectively be remedied by judicial instruction.”[26]

Therefore, notwithstanding the advocate’s desire to persuade by all legitimate means, it is beyond argument that as to the search for truth evidence or argument intended or appearing to promote bias, appeal to prejudice or which may distract the trier-of-fact from her or his true task has been vigilantly guarded against.

The “Battle” for Neutrality and Fairness

Impartial, neutral fact-finding is not easily achieved. Maintaining objectivity is a constant struggle even without evidentiary or argumentative attempts at distraction.

The need for, and difficulty of, resisting bias has been described by Justice Anthony Kennedy of the United States Supreme Court:

“I have been a judge for over twenty years, and I am surprised how often I have to go back to the very beginning and ask, ‘am I controlled by some hidden bias, some pre-disposition, some predilection, some prejudice that even I cannot see? What is it that is urging me to decide the case in this particular way?’ I have to examine my own background and my own intellectual position to ensure that I am being fair. The battle for neutrality, the battle for fairness in the judge’s mind never ends. You have to have some outward structures that enable you to strive for perfect neutrality…but you may never reach it because we are all the product of our own biases and background.”[27]

In “Demonstrative Advocacy”, Fancy cited the following extract from the Supreme Court of Canada decision in R. v. R.D.S., a Canadian case where racism was seen by at least the trial judge to have possibly played a role in an arrest:

“There is in each of us a stream of tendency, whether you choose to call it philosophy or note, which gives coherence and direction to thought and action. Judges cannot escape that current any more than other mortals. All their lives, forces which they do not recognize and cannot name, have been tugging at them – inherited instincts, traditional beliefs, acquired convictions; and the resultant is an outlook on life, a conception of social needs….in this mental background every problem finds its setting. We may try to see things as objectively as we please. Nonetheless, we can never see them with any eyes except our own.”[28]

Nevertheless, judges are required to make factual determinations solely by being open to and considering only relevant and necessary evidence and giving such evidence its appropriate weight.

Fancy argued in relation to R. v. R.D.S. that: “The justices admitted that the differences in the findings and holdings of judges are influenced by ‘their individual perspectives on the world.’ However, like Justice Cory, they then re-labeled these subjectivities or biases as ‘common sense’ as opposed to ‘matters not in evidence’ (as Justice Major did…).”[29]

Fancy also argued that the justices did not explain where to draw the line between “experiences of judges” that “assist them in their decision-making process” and experiences that prevent a fair and just determination of the cases based on the facts in evidence.[30]

Thus, the battle for neutrality and against bias, prejudice or distraction is never easy and it is mandatory as regards at least expert evidence that “the search for truth excludes… evidence which may distort the fact-finding process”, which exclusion is to be ordered by judges taking seriously their gatekeeper function.[31]

Further, there is no basis for limiting the exclusionary rule to expert evidence or for treating demonstrative evidence any differently when such evidence may distort the fact-finding process.

Demonstrative Evidence

Under the heading “What Is Demonstrative Evidence?”, Anne Kirker and Lara Mason suggested that “the academic literature dealing with demonstrative evidence is fragmented and variable.”[32]

Barbara Legate wrote in January 1996 that “the task of defining and categorizing demonstrative evidence is not an easy one.” When she updated her article a decade later, the phrase remained.[33]

Ms. Legate urged that there be clarification of the type of visual evidence being adduced at the time of its introduction so as to permit the court to properly rule on its admissibility.[34]

Jennifer Mnookin argued in her essay on photographic evidence[35] that:

“Demonstrative evidence has continued to hover awkwardly on the boundary between illustration and proof. In their analysis of the topic, Robert Brain and Daniel Broderick described the tremendous conceptual confusion that still besets ‘demonstrative evidence,’ pointing out that ‘there is not even a settled definition of the term.’ Some commentators define demonstrative evidence to include all evidence that consists of ‘things’ rather than testimony, ‘all phenomena which can convey a relevant firsthand sense impression to the trier of fact.’ Others limit its definition to those displays ‘principally used to illustrate or explain other testimonial, documentary, or real proof… a visual (or other sensory) aid.’ Some definitions deem it substantive, independent evidence, while others insist it serves merely the secondary, derivative purpose of illustration.”[36]

John Olah in The Art and Science of Advocacy cited Wigmore as having identified three major categories of evidence:

Direct or testimonial evidence;

Indirect or circumstantial evidence, and

Demonstrative evidence.

Olah separated demonstrative evidence into two categories:

real evidence, being the object involved in the incident giving rise to the subject-matter of the lawsuit (the alleged weapon in a murder case or the failed product in a product liability case), and

illustrative evidence, or evidence that serves to explain or to illustrate testimony to the trier-of-fact so that the trier can better appreciate oral testimony. Examples include photographs, diagrams, charts and models.[37]

Sheila Block in Modern Trial Advocacy: Canada[38] drew the same distinction between “real evidence” and “demonstrative evidence”, however did not treat these as sub-categories of the latter term. In describing demonstrative evidence as that which is used to illustrate or clarify a witness’ testimony, such as models, graphs, diagrams, charts, drawings or other objects that explain or illustrate issues in the case, Ms. Block wrote:[39]

“The distinguishing feature of demonstrative evidence is that it is lawyer-generated. Real evidence exists by virtue of the activities of the parties and witnesses in the case. Counsel can search, discover it, preserve it and use it, but a lawyer can never create real evidence. Demonstrative evidence is not intrinsic to the case. It is never handed to counsel, but must be developed by the lawyers as an aspect of the presentation of the case.”[40]

Pacciocco and Stuesser also distinguish “real evidence” from “demonstrative evidence” in The Law of Evidence.[41] The latter evidence is described as “aids used to help witnesses better illustrate or explain their evidence”.

Chayko and Gulliver in Forensic Evidence in Canada[42] suggest that “real evidence” means the physical item or document that becomes an exhibit and from which the judge can make conclusions from direct perception. The authors suggest that it is not accurate to call “real evidence” by the label “demonstrative evidence” although this is frequently done in the United States. They suggest that “demonstrative evidence” is more correctly reserved for evidence “presented by way of demonstration or by simulating the real evidence”. They include plans, models and demonstrations as representing this type of evidence from which the judge “can infer from the results what really happened”.[43]

Retired Ontario Superior Court Justice Donald Ferguson wrote in Ontario Courtroom Procedure[44]:

“The use of demonstrative evidence and aids is relatively new to trial practice, and the terminology is not settled. Consequently, a variety of terms are employed, thus leading to some confusion.

“While the term ‘image’ is commonly used to refer generally to all forms of aids and demonstrative evidence, the term is clearly too narrow.

“To be more useful, the terms employed should relate to some of the fundamental issues involved in determining the proper use of such items. One of the key issues is whether the ‘image’ is to be used:

– as an aid to assist the trier of fact to understand evidence or argument; or

– as evidence to prove a fact.

“I. Demonstrative Aid

To highlight this distinction, it is suggested that the term ‘demonstrative aid’ be used to refer to something which is used to assist the trier of fact to understand evidence or argument…the reproduction of an exhibit…a chart or graph…

“the use of the term ‘demonstrative aid’ conveys the purpose of the aid; that is, it not intended to prove facts but rather to aid the trier of fact to understand evidence or submissions.

“II. Demonstrative Evidence

It is suggested that the term ‘demonstrative evidence’ be used to refer to an image or item which is tendered to prove a fact…photographs, videos, and computer simulations which demonstrate or exemplify something for the purpose of proving a fact other than by testimony.”

Justice Ferguson envisioned situations where an object used as a demonstrative aid in an opening address to the jury might later be proven and made an exhibit and thus become demonstrative evidence.

Brain and Broderick[45] suggest that demonstrative evidence is “any display that is principally used to illustrate or explain other testimonial, documentary, or real proof or a traditionally noticed fact. It is, in short, a visual (or other sensory) aid.”

The authors suggest that the most common types of demonstrative evidence are:

in court demonstrations, recreations or experiments;

models or other tangible objects;

charts, diagrams and maps;

photographs, movies and videotapes;

jury views, and

computer-dependent animations and simulations.[46]

The authors indicated that whether a particular display is demonstrative or substantive evidence does not depend on the physical appearance of the display, but rather on the principal purpose for which the display is offered at trial. “If the primary purpose of the display is to illustrate or explain other evidence, it is being used demonstratively; in other words, its evidentiary role is dependent and indirect. If it is being used primarily to prove the existence or non-existence of a fact or consequence, the display is being used substantively; its evidentiary role is thus independent and direct.”[47]

David Hennes adopted Brain and Broderick’s definition.[48] However, he cautioned that: “classifying all evidence that is considered ‘visual’ as demonstrative, however, can be misleading.”[49] “Real evidence provides the trier of fact with an opportunity to draw a relevant first hand sense of impression and involves production of an object which usually has a direct or indirect part in the incident. Purely demonstrative evidence, on the other hand, is derivative in nature, as it only illustrates or clarifies other substantive evidence. Thus real evidence, possessing independent probative value, may be carried with the jury into deliberations. Demonstrative evidence, with no independent probative value, may not enter the jury room.”[50]

Hennes also suggested that demonstrative evidence such as crime scene reenactments are purely demonstrative evidence since they are a post-event creation prepared exclusively for trial.[51]

In this paper I use the term “demonstrative evidence” as it was defined by Brain and Broderick: “a display used principally to illustrate or explain other testimonial, documentary or real proof” or “a visual or other sensory aid”. It will invariably be lawyer-generated but there is the arguable exception such as the in-court demonstration in which real evidence is used to corroborate or refute other testimonial evidence. Reference to a well-known, and obviously fact-distorting, in-court demonstration is made later in this paper.