Video Experts: A ‘Must Have’ or ‘Nice to Have’ at Trial?

An issue that is sometimes raised at trial by counsel or the court is whether the expert testimony of a forensic video analyst is necessary to effectively present video evidence. Counsel may find themselves in the position where if they propose to call an expert, opposing counsel will argue that such expert evidence is not necessary. Yet, if they don’t call an expert, opposing counsel will criticize that failure and argue that an expert should have been called. The purpose of this article is to offer some guidance to counsel and forensic video analysts as to when an expert witness should be called for trial purposes.

One of the four requirements for the admission of expert evidence is that it must be necessary to do so. What that means in practice is that it must be established that the trier of fact (the jury if there is one, otherwise the judge) would likely be unable to form a proper judgment regarding certain evidence or issues without expert assistance. This in turn is dependent on the purposes for showing the video recording and what questions it is being used to answer.

If a video recording is being used for the purpose of depicting an event and the event is technically and visually uncomplicated and counsel is not asking more of the images than to depict the event, an expert is likely not required as the expert would likely add little to the narrative (assuming there is no additional information to be gleaned from the images). For example, in State of New Jersey v. Knight, 259 N.J. 407 (2024), the Supreme Court of New Jersey considered the issue of whether a video expert should have been called at trial. In this robbery trial, part of the evidence relied on by the prosecution was a six-second CCTV video recording that showed the defendants and the soon-to-be victim walk by a business and move out of camera view where the robbery occurred. The jury requested to see the video during their deliberations and wanted to view the video in slow motion. The issue raised on appeal was whether they should have been allowed to do so without expert assistance in the courtroom. The Court agreed with the Appellate Division, which noted:

Watching a video in slow motion is a commonplace method of playing a video that is not beyond the ken of an average juror. Pushing a button to play a video at a speed slower than normal to assist the jury in viewing the difficult-to-perceive recording here was not an alteration or distortion of the video. It was the same exact video — simply played in slow motion.

The Court referred to State v. Watson, 254 N.J. 558 (2023), wherein the Supreme Court of New Jersey had occasion to opine on this issue. There, the Court noted that in contrast to cases wherein ‘elaborate forensic video techniques’ are used, ‘[s]pecialized knowledge would not ordinarily be required for other types of adjustments, like adjusting the speed of a video or creating a straightforward composite video, a screenshot, or an enlarged photo from a video.’ [That statement is not universally correct as some of those tasks do require forensic expertise.] In Knight, the Court held that slowing the recording did not change or distort the images and served to aid the jury in examining the events at a more suitable pace. Accordingly, no expert assistance was required. The Court noted that if the video recording is altered or is used to create new evidence using specialized techniques, a qualified expert may be required to testify to those processes. In Watson, the Court specifically noted that image enhancement and ‘pixel tracking’ would require expert evidence.

The Knight case illustrates the point that when a recording is not complex and is readily understandable by the trier of fact, an expert will rarely be necessary. That said, sometimes counsel’s assessment of the value of the video recording may not be well-informed. There have been many cases wherein a forensic video analyst has been able to draw considerable value from video images, far beyond what counsel initially perceived. Therefore, there is merit in having an expert examine video evidence to determine if there is more than meets the untrained eye.

It follows that the involvement of a forensic video analyst may be required to unlock the full value that a video recording has to offer. Many technical and analytical functions could not be properly performed, let alone presented at trial, without the services of a qualified forensic video analyst. Examples of such functions include the following:

• Authentication
• Active and passive forgery detection
• Image clarification
• Image interpretation, especially considering issues stemming from compression, reduced or variable frame rates, and other image accuracy challenges
• Image comparison
• Reverse projection
• Height determination (photogrammetry)
• Speed determination from video
• Motion tracking
• Geolocation and chronolocation

Note that not all forensic video analysts are qualified to perform all these functions as they are rather complex and require specific training.

There are many examples wherein expert evidence was clearly required as it was necessary to assist the court in reaching an informed conclusion, but was not utilized. When that occurs, the trier of fact may attempt to figure it out themselves, without the requisite guidance, and is likely to reach an incorrect conclusion. Alternatively, the trier of fact will do without and make an uninformed decision based on the evidence as presented. Examples wherein trial judges engaged in their own forensic analysis and faltered have been highlighted on this website (see for example R. v. Ermine (2018) and R. v. Benn (2026)). When a jury engages in such analysis in the privacy of the jury room, the risk of error is high.

Getting back to the title of this article – are video experts a ‘must have’ or a ‘nice to have’ at trial? At the investigative stage in a criminal case, whether an expert is consulted will depend on whether the investigators have any familiarity with what forensic video analysis has to offer. The less they know, the less likely they are to seek expert assistance. The more they know, the more likely they are to seek assistance in gaining the full value from video evidence. Involving an expert at the investigative stage may significantly impact the course of an investigation – more information earlier on generally leads to more informed decisions. At the counsel level, counsel also need to assess whether proffered video evidence should be accepted at face value or whether it should be subjected to forensic video analysis.

Fundamentally, this is a question of visual literacy. Making decisions about the potential value of video evidence without the necessary technical and analytical expertise means that incorrect assessments may be made. Video evidence may be misinterpreted, leading to incorrect decisions about a case, or the full value of the images may remain locked and unavailable to the trier of fact. It is not realistic to expect counsel and judges to achieve any level of expertise, nor is that their job. What is reasonable to expect is that they seek expert assistance when dealing with video evidence that may be more complex and challenging than is first apparent.