Currently, a murder trial is underway in Chicago wherein former Chicago police officer Jason Van Dyke is charged with unlawfully killing Laquan McDonald by shooting him 16 times. The shooting was captured on police dashcam video. The prosecution called FBI forensic video analyst Mark Messick who had enhanced the video evidence and inserted arrows which purported to show when McDonald was hit by gunfire.
Van Dykes’s attorneys argued that Messick’s evidence should be excluded on the basis that while he was qualified as an expert in forensic video analysis, he was not qualified as a ballistics expert and therefore testified beyond his area of expertise. Even though Messick testified that he worked with a ballistics expert in preparing his video evidence, the trial judge ruled that his evidence was inadmissible and told the jury to disregard all of his evidence.
By agreement of counsel and the trial judge, Messick was permitted to retake the witness stand the next day and give evidence again but was limited to his video analysis only. He was not permitted to give any evidence pertaining to ballistics.
The situation that arose during the testimony of Mark Messick illustrates that dangers that lurk when an expert witness testifies beyond his/her area of expertise. In an earlier article posted to this website entitled “Stay Within Your Lane!: The Importance of Knowing Your Boundaries as an Expert Witness”, I set out the pitfalls of an expert witness exceeding stated qualifications in testimony. I recommend reading that article to put the Chicago case in context.
It is entirely proper for a forensic video analyst to testify about all technical aspects of video evidence. That is why the witness has been called to the stand. However, the interpretation of what is shown in the video may fall outside of the analyst’s education, training and experience. This is not a failure on the part of the analyst, but rather an illustration of the fact that experts in one area of expertise are not necessarily experts in other areas of expertise.
We see this overreaching in other areas as well. Experts in gait analysis should not give evidence based on human movements recorded on video without the benefit of evidence from a forensic video analyst who can properly interpret the video. This will help to address issues of frame rate, compression, aspect ratio and image resolution which must be factored into any opinion about gait. Similarly, nor should a collision reconstruction expert give expert evidence about speed determination from video images without the assistance of a forensic video analyst.
This is not to say that a forensic video analyst could never give evidence about the moment when a gunshot occurs. It depends on the experience and qualifications of the expert. For example, in State of Idaho v. Almaraz, 2012 WL 1948499 (Supreme Court of Idaho), the State called a forensic video analyst who narrated the surveillance video evidence for the jury and opined as to the exact moment when the victim was shot. On appeal, the Supreme Court ruled that the trial judge properly exercised his discretion in permitting such evidence at trial on the basis of the expert’s experience in analyzing surveillance video and his personal experience of having seen people shot in the past.
Attorneys must be cautious and not expect more from an expert witness than the expert can fairly deliver. Overreaching can harm an expert’s reputation and the case before the court. Where more than one expert is required to tell the whole story, then that is the approach that must be followed. For example, in the Chicago case, the arrows should have been added only when the ballistics expert testified about the video as that is the expert well versed to comment on the shooting. Expert witnesses must draw clear lines in the sand setting out the parameters of their expertise and to thereafter remain within those limits.