Jonathan W. Hak, Q.C., Dipl., B.Sc., LL.B., LL.M., PhD Candidate[i]
Introduction
Accurate and detailed depictions of crime scenes, areas of interest, and objects provide investigators, counsel, and the court with data necessary to more fulsomely comprehend available evidence and to understand what occurred.[ii] Scene measurements, including the location of objects and features within the scene, are central to a proper scene reconstruction, especially given that scenes are transient and ephemeral and that what may seem unimportant at the outset could take on great significance at trial.[iii] This paper provides an overview of the use of terrestrial LiDAR scanning devices for scene measurement and reconstruction and focuses on legal considerations and recommendations for the use of such evidence in a criminal trial.
A. What is Terrestrial LiDAR Scanning?
Light detection and ranging (LiDAR) technology is a remote sensing technology that measures distance by illuminating a target with a laser and analyzing the reflected light. Terrestrial LiDAR scanning devices, also referred to as terrestrial laser scanning (TLS) devices emit laser beams into the selected environment while rotating horizontally and vertically. The scanner measures the distances and angles from the intensity of the reflected beams and computes the three-dimensional (3D) coordinates of all reflected targets to create a 3D point cloud consisting of millions of points. These points produce a detailed and highly accurate 3D depiction of the scene.[iv]
Two-dimensional depictions of scenes limit the ability of the viewer to accurately assess spatial relationships of the overall scene and features and objects located within it.[v] They are also less suitable for reconstructing scenes and events using computer-generated animations or virtual reality walkthroughs.[vi] Three-dimensional laser scanning allows investigators to capture the entire geometry of a scene, including objects and other relevant aspects that may not have been noted when the evidence was gathered, thus ensuring the longevity and preservation of the scene for a subsequent comprehensive examination.[vii] The efficiency that TLS affords in documenting a scene saves investigators valuable time at the scene and records data that may not initially appear relevant but may take on significance later.[viii]
B. The Use of TLS in Criminal Justice Applications
TLS can be used to capture extensive scene details for later analysis and visualization, and is used most commonly, though not exclusively, with crimes scenes and motor vehicle collisions.[ix] Multiple scanning technologies can be used to accurately measure outdoor and indoor scenes, as well as vehicles and other objects. Combining different tiers of scanning technology provides a varied perspectival view of an event, maximizing the data that can be obtained from it.[x] TLS has also been used for bloodstain pattern analysis and violent crime reconstruction,[xi] as well as to examine solar irradiance for cadaver decomposition in forested environments.[xii]
Crime scenes can be documented three-dimensionally in addition to other conventional methods.[xiii] TLS devices can quickly scan large areas, buildings, rooms, and vehicles, generating point clouds with millions of points with accuracy ranges up to one millimeter.[xiv] This data can be used to create a virtual reality application for virtual scene walkthroughs.[xv] Virtual walkthroughs are valuable because crime scenes cannot be held indefinitely and deteriorate with time. Further, virtual walkthroughs can be conducted anywhere, anytime, without the danger and inconvenience that may accompany scene visits. Virtual walkthroughs depicting the witness’s first-person view are particularly helpful as they show the scene from the witness’s perspective,[xvi] though it should be noted that researchers report that distances in virtual reality are underestimated for larger spaces and viewers need to be cautioned accordingly.[xvii]
C. Legal Requirements for Admissibility
Judges are required to act as gatekeepers and to ensure that technical evidence is admitted only upon a showing of scientific validity and reliability by its proponent.[xviii] Therefore, in order for TLS evidence to be ruled admissible, the court must be satisfied that the tests of scientific validity and reliability have been met. It follows that witnesses presenting this evidence must be adequately trained and fully qualified to address these critical issues. It is not sufficient to simply know how to use the instrument. The TLS device operator must be fully qualified to operate the instrument and must have a working knowledge of it including how it works and what it is designed to do. This level of knowledge is required of any witness who presents computer-generated evidence in court.[xix] Errors in measurement, calibration, forensic workflow, and insufficient technical knowledge by operators can result in the irreversible loss of evidence.[xx] When working in an ISO 17020 environment, competency testing is required for all work conducted at a crime scene. Further, all measuring devices must be calibrated within approved tolerances with a clearly defined limit of accuracy.[xxi]
TLS device operators who collect but do not analyze the data are required to testify and may be called as fact or technical witnesses, as opposed to expert witnesses, if they are not called upon to opine upon the meaning of the data. If the operator is likely to be asked involved questions about the operation of the instrument, the accuracy of the data, whether all requisite data was captured, etc., then it is preferable to have the operator qualified as an expert witness to allow those opinions to be given, although there must be a clear demarcation between the role of the operator and the analyst, assuming these functions are split. If the operator is also the analyst, this demarcation is not necessary.
All data gathered from digital scanning requires interpretation by an expert.[xxii] Where data is gathered by an operator and then given to an analyst for detailed evaluation and further processing for presentation, the analyst must be qualified as an expert witness, specifically in the evaluation, interpretation, and processing of data gathered by TLS devices. Before this step can be taken, the analyst must have sufficient targeted education, training, skill, and experience to rise to the level expected of an expert witness. No specific minimum legal standards have been set for TLS device operators or TLS data analysts. Oversight agencies and agencies who use TLS devices must establish robust training programs to ensure that only qualified personnel engage in this highly technical scientific work.
Data generated by TLS devices must be authenticated in order to be admissible. Authentication requires that the party seeking to introduce technical data must establish that the data is in fact that which it purports to be and that the data itself is accurate and reliable. This requirement is set out in Federal Rules of Evidence Rule 901, equivalent provisions in state codes of evidence, and by common law. Technical evidence is prone to being excluded for lack of authentication not because it is incapable of being authenticated but because the attorney leading the evidence has not adequately prepared with the technical or expert witness to meet this requirement.
Interestingly, there exists a lack of standards for how digital measurement data should be recorded, preserved, processed, and presented.[xxiii] Proper standards and standard operating procedures (SOPs) are essential components of forensic science.[xxiv] Agencies who use TLS devices should utilize uniform, scientifically valid procedures so that the evidence gathered will withstand robust technical and legal challenges in court.
TLS data errors can result from systematic error and human error. Systematic errors involve erroneous coordinate values whereas human error concerns the generation of inaccurate measurements.[xxv] Further, digital evidence is fragile and may fall prey to intentional or inadvertent alteration during acquisition or subsequent processing.[xxvi] Accuracy and reliability are the cornerstones of electronic scene measurement and recreation and therefore the collection of digital scene data must be accomplished in a forensically sound manner. In order to present a strong case for admissibility, the following procedures should be followed:[xxvii]
- Details regarding the capture, storage, and transmission of digital scene data must be adequately documented, preserved, and available for review by interested parties.
- Digital scene data should not be altered between the time of collection and its use in court, and should any alteration occur, it must be fully documented.
- Access to original data must be restricted to qualified individuals who understand the need to preserve the integrity of the data.
- Integrity verification is an essential precondition.
- Proper chain of custody documentation requires an accounting of the chronological history of the evidence, with all steps from creation to presentation noted. Therefore, a comprehensive audit trail recording the digital lifespan of the measurement data should be maintained and available for review.
A further consideration regarding the evaluation, interpretation, and presentation of TLS data is that of peer review. The US Supreme Court stated in Daubert v. Merrell Dow Pharmaceuticals Inc.[xxviii] that peer review is one of the factors trial judges should consider when assessing admissibility. Peer review by a qualified, competent reviewer is not a legal requirement but is a valuable component of proper forensic practice. In cases where an analyst has formed opinions about a scene based upon the evaluation and interpretation of TLS data, it is recommended that a meaningful, thorough, and documented peer review be conducted.
D. Judicial Reception of TLS Data
TLS data can be used as real evidence or demonstrative evidence. Real evidence has evidential value and can be used to determine the facts in a case. Demonstrative evidence is designed to illustrate viva voce and other forms of evidence by way of a visual recreation.[xxix] It may take the form of photographs, video, diagrams, charts, 3D models, 3D laser scans, and other computer-generated animations. As a matter of law, it has no independent evidential or probative value. In order to make the most use of TLS data, counsel tendering such evidence should seek to have it admitted as real evidence, accompanied by expert evidence authenticating it and interpreting the data for the court.
There is limited jurisprudence on the use of TLS data in criminal and civil cases in the United States. Reported case law refers to the use of TLS data and intimates that it was used as part of the judicial analysis. Though most of the reported cases are civil cases, the rulings are equally applicable in the criminal realm. A particularly helpful case is Cyr et al. v. Weber,[xxx] a negligence action arising out of a motor vehicle collision. An expert in highway safety, accident reconstruction, and traffic engineering presented TLS evidence which he had obtained from the scene and from which he produced 3D images and animations for use in court. The expert testified that he created an accurate 3D environment using the TLS scans, the dimensional specifications of the vehicles, and the relative placement of the vehicles. The court found the TLS methodology, including the scanner, the 3D software, and the analysis, to be generally accepted within the scientific community. The court further found that the scanner used had been tested and subjected to peer review. The evidence was found to be scientifically valid and reliable. Utilizing a Swinton analysis, the court found that the computer-generated evidence presented was suitable for the purpose tendered and that the technology was reliable. At the request of the party presenting the TLS evidence, the evidence was offered for illustrative purposes only.
In United States v. Slager,[xxxi] during the sentencing hearing of a former police officer being sentenced for the fatal shooting of a man, the defendant presented expert evidence from a forensic analyst who created a 3D digital model of the crime scene using video evidence and TLS data obtained by investigators. The 3D model allowed the court to see the defendant and the man from different angles and to examine varying theories as to what occurred. The court admitted the expert evidence generally but did not accept the expert’s interpretation of the data. The data and the technology used were not challenged, only the expert’s interpretation of it, which the court found not to be credible given other evidence in the case.
TLS devices and the use of TLS data to create a 3D environment to examine a scene was further endorsed in Gecker as Trustee for Collins v. Menard, Inc.,[xxxii] a case involving a shopping cart related injury. The plaintiff sought to have the defendant’s experts prevented from testifying in the case. One of the defendant’s experts utilized 3D scans of the store entrance and created 3D digital models of the shopping cart train which allowed him to recreate how the shopping cart train struck the plaintiff. The plaintiff challenged the reliability of photogrammetry and the TLS point clouds used to create the 3D model. In rejecting the plaintiff’s argument, the court found that the photogrammetry and TLS data used by the expert were not “new techniques”. The court found the expert evidence to be standard, peer-reviewed, tested techniques and that the data and methodology used constituted reliable science. Accordingly, the expert was permitted to testify at trial.
In Koenig and Everett v. Johnson,[xxxiii] a motor vehicle-pedestrian collision case, the defendant sought to present evidence from an expert in engineering and accident reconstruction. The expert utilized TLS data obtained from the scene, together with other evidence, to produce a 3D reconstruction of the scene and event. The court found the expert evidence sufficiently reliable to warrant admission, noting that the plaintiffs could challenge the expert’s opinions at trial.
I have not located any cases wherein the court criticized TLS data or the use of it in the case, nor have I found any cases where there were serious challenges to the evidence. Unless the parties disagree on the admissibility or use of the data and present opposing expert evidence, there is often little need for the judge to comment upon it, hence the paucity of case law. For example, in Stapleton v. Union Pacific Railroad Company,[xxxiv] 3D laser scanning was utilized to examine a low-speed locomotive collision, but little detail was given as to how it was used in the application to exclude expert testimony. The TLS evidence was not excluded in this pre-trial motion. Similarly, in State v. Odum,[xxxv] the defendant presented testimony from two members of a private forensics company who utilized a 3D laser scanning instrument to reconstruct the crime scene. They testified that as a result of their work, they determined that the police had erred in their measurements regarding bullet trajectory and impact location. This was confirmed by an expert in ballistics, crime scene reconstruction, and bullet trajectory. It does not appear that the TLS evidence was challenged. Further, no details were given in the appellate judgment regarding the work of police investigators nor did the measurement variance have any impact on the convictions registered at trial. However, the case has some value because it is an example of TLS evidence being admitted at trial and referred to by an appellate court. Finally, in Dalton v. USA,[xxxvi] 3D laser scanning was used to reconstruct the events leading up to a fatal motor vehicle collision. The court found the evidence of value in understanding the actions of each of the vehicles involved. None of the above cited cases are determinative although Cyr et al. v. Weber is a reasonably strong endorsement of TLS evidence and 3D scene reconstruction being used as demonstrative evidence. It will take time to develop a robust body of case law on the use of TLS data in litigation.
E. Educating Attorneys and Judges on the Use of TLS Data in Court
As with most technical evidence that is new or relatively new to the courtroom, it is essential that attorneys who present TLS evidence have a sufficient understanding of the basics of TLS scanning and the creation of 3D depictions of scenes so that they can lead and defend the evidence with confidence. They must also possess the requisite legal knowledge to address the need for authentication and the proper classification and use of the evidence in the courtroom. Attorneys leading evidence they do not understand risk adverse judicial rulings that can have a ripple affect across the jurisprudence. Accordingly, a seminar designed to achieve these objectives is worthy of consideration.
Providing training to the judiciary would also be of value but this is entirely dependent upon whether the judiciary wishes to receive training. Judicial independence issues sometime limit the ability of outside parties to provide training that might be viewed as partisan, even though it is not. Training the judiciary, while helpful, is not an essential component of using TLS data in court because judges are required to learn about the case, case data, and the technology used through evidence called by the parties. That is the role of expert witnesses, with the assistance of attorneys who lead and argue the evidence. Judges are not permitted to take judicial notice of technology that is outside the realm of common knowledge. TLS devices and data would not be classified as common knowledge.
Conclusion
The use of TLS devices to obtain detailed and accurate measurements of scenes, areas of interest, and objects is an important adjunct in the search for the truth. The ability to view locations of interest in a 3D environment can be very helpful to counsel and the court in visualizing an event and different theories as to how it occurred. Central to the use of TLS devices and TLS data is qualified and properly trained device operators and data analysts. TLS device operators and data analysts must have a thorough understanding of the technology being used, an understanding of the acceptable parameters for the use of such technology in court, and the ability to effectively communicate their evidence in court, especially when being challenged. TLS device operators and data analysts should consider themselves to be teachers whose role it is to educate attorneys, judges, and jurors.
From the limited reported case law in the United States, some trends can be discerned. Courts are expressing epistemic value in TLS evidence. In order for the evidence to be admitted, there must be a robust showing of scientific validity, including data accuracy and presentation reliability. The court will assess the weight to be given to the evidence, similar to the way it will assess all scientific evidence. Whether TLS evidence is accepted as real evidence or demonstrative evidence is dependent upon the approach taken by counsel and the expert evidence presented.
Endnotes
[i] Barrister and Solicitor; PhD Candidate (Leiden University Faculty of Law, Institute for Public Law, Grotius Centre for International Legal Studies); Adjunct Associate Professor (University of Lethbridge); Law Lecturer. Email: jonathan@jonathanhak.com
[ii] Agosto, E. et al. (2008) Crime Scene Reconstruction Using a Fully Geomatic Approach. Sensors, 8, 6280-6302, at 6281.
[iii] Sheppard, K., Cassella, J.P., and Fieldhouse, S. (2017). A Comparative Study of Photogrammetric Methods Using Panoramic Photography in a Forensic Context. Forensic Science International, 273, 29-38, at 29-30.
[iv] Buck, U. et al. (2011). 3D Bloodstain Pattern Analysis: Ballistic Reconstruction of the Trajectories of Blood Drops and Determination of the Centres of Origin of the Bloodstains. Forensic Science International, 206, 22-28, at 23; Forensic Technology Center of Excellence, ‘Meeting Report: Terrestrial LiDAR Scanning Working Group for Criminal Justice Applications, First Meeting’, July 2020, available online at https://forensiccoe.org/private/5f03238d5a9aa (accessed 17 November 2020), at 1.
[v] Urbanová, P. et al. (2017). Using Drone-Mounted Cameras for On-Site Body Documentation: 3D Mapping and Active Survey. Forensic Science International, 281, 52-62, at 53, 60.
[vi] Ibid, at 53.
[vii] Forensic Technology Center of Excellence, ‘Landscape Study on 3D Crime Scene Scanning Devices (with 2018 Update)’, available online at https://forensiccoe.org/private/5dd6ad2d0ffeb (accessed 17 November 2020), at 10 of 2016 Study.
[viii] Mullins, R.A., ‘Virtual Views: Exploring the Utility and Impact of Terrestrial Laser Scanners in Forensics and Law’, M.A. thesis, University of Windsor, 2016, at 4-5.
[ix] Baier, W. et al. (2020). A Holistic Multi-Scale Approach to Using 3D Scanning Technology in Accident Reconstruction. Journal of Forensic Sciences, 65, 1774-1778; Bucheli, S.R. et al. (2014). Terrestrial Laser Scanning to Model Sunlight Irradiance on Cadavers Under Conditions of Natural Decomposition. International Journal of Legal Medicine, 128, 725-732, at 726.
[x] Baier, supra note 9, at 1776.
[xi] Buck, supra note 4.
[xii] Bucheli, supra note 9.
[xiii] Sieberth, T. et al. (2018). Applying Virtual Reality in Forensics – A Virtual Scene Walkthrough. Forensic Science, Medicine and Pathology, 15, 41-47, at 41.
[xiv] Ibid, at 41.
[xv] Agosto, supra note 2, at 6281.
[xvi] Sieberth, supra note 13, at 46.
[xvii] Ibid.
[xviii] Daubert v. Merrell Dow Pharmaceuticals Inc., 113 S. Ct. 2786 (US Supreme Court); Federal Rules of Evidence, Rule 702.
[xix] State of Connecticut v. Swinton, 268 Conn. 781; 2004 Conn. LEXIS 190 (Connecticut Supreme Court 2004).
[xx] Urbanová, supra note 5, at 59.
[xxi] Sheppard, supra note 3, at 30.
[xxii] Baier, supra note 9, at 1776.
[xxiii] Church, E., ‘The Forensic Utility of Photogrammetry in Surface Scene Documentation’, M.Sc. thesis, Boston University School of Medicine, 2019, at 5.
[xxiv] Chisum, W.J. and Turvey, B.E. (2007). Crime Reconstruction, Massachusetts: Elsevier Academic Press, at 116.
[xxv] Mullins, supra note 8, at 14.
[xxvi] Bulbul, H.I., Yavuzcan, H.G., and Ozel, M. (2013). Digital Forensics: An Analytical Crime Scene Procedure Model. Forensic Science International, 233, 244-256, at 245.
[xxvii] Ibid, at 245.
[xxviii] Supra note 18.
[xxix] Sainato, V.A. (2009). Evidentiary Presentations and Forensic Technologies in the Courtroom, The Director’s Cut. Journal of the Institute of Justice and International Studies, 9, 38-52; Mnookin, J. (1998). The Image of Truth: Photographic Evidence and the Power of Analogy, Yale Journal of Law and the Humanities, 10(1), 1-74, at 67-70.
[xxx] Cyr et al. v. Weber, 2016 WL 3202426 (Superior Court of Connecticut).
[xxxi] United States v. Slager, 2018 WL 445497 (US District Court, South Carolina).
[xxxii] Gecker as Trustee for Collins v. Menard, Inc., 2019 WL 3778071 (US District Court, N.D. Illinois, Eastern Division).
[xxxiii] Koenig and Everett v. Johnson, 2020 WL 2308305 (US District Court, South Carolina).
[xxxiv] Stapleton v. Union Pacific Railroad Company, 2020 WL 2796707 (US District Court, N.D. Illinois, Eastern Division).
[xxxv] State v. Odum, 2017 WL 5565629 (Court of Criminal Appeals of Tennessee).
[xxxvi] Dalton v. USA, 2014 WL 7423760 (US District Court, E.D. New York).