This paper examines demonstrative evidence as it is used in modern courts and legal proceedings. It defines the concept, catalogues common forms such as photographs, video recordings, x-rays, computer-generated imagery, and animations, and explains how demonstrative evidence functions to illustrate witness testimony and establish context within a case. The paper also addresses the authentication requirements under Rule 901 of the Federal Rules of Evidence, detailing the methods by which different types of demonstrative evidence must be verified before being admitted. Finally, it briefly compares authentication procedures for demonstrative and substantive evidence, noting key similarities and distinctions in their chains of custody.
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Demonstrative evidence is widely used in today's courts and legal systems. Essentially, it is all evidence that represents an object or person — rather than the real object itself. According to the research, "demonstrative evidence is that evidence addressed directly to the senses without intervention of testimony. Such evidence is concerned with real objects such as charts, graphs, videotape, and computer animation, which illustrate some verbal testimony" (Marks, 2004). Such types of evidence help establish a sense of context within any given case or scenario, thereby augmenting actual physical evidence and strengthening the overall case. Demonstrative evidence can support physical evidence or stand alone to help show guilt or motive based on its ability to "illustrate the testimony of a witness to help the jurors understand difficult factual issues" (Marks, 2004). As such, demonstrative evidence aims to demonstrate some concept related to the case, and is therefore quite different from substantive evidence.
There are a wide number of examples of demonstrative evidence. These include pictures, sound recordings of conversations, video-recorded evidence, x-rays, simulations of events, professional sketches, drawings, animations made to represent real-life scenarios, computer-generated imagery, and physical models. Each of these forms serves to represent or recreate an object, person, or event in a way that makes the facts of a case more accessible to a jury.
Demonstrative evidence must be properly authenticated before it can be used in a court of law. Authentication is governed by Rule 901 of the Federal Rules of Evidence. Essentially, "to satisfy the requirement of authenticating or identifying an item of evidence, the proponent must produce evidence sufficient to support a finding that the item is what the proponent claims it to be" (Cornell University Law School, 2013). A number of methods traditionally satisfy this requirement, including: a testimony by a witness with knowledge about the case or scenario; comparison by an expert witness; clearly distinctive characteristics that show the likeness of the item to the circumstance; a witness's opinion about the sound of a voice; times and transcripts of a telephone conversation; public records; and other methods as approved by state statutes.
In order for data or documentary demonstrative evidence to be admitted in court, it must be "in a condition that creates no suspicion about its authenticity" (Cornell University Law School, 2013). Pictorial evidence can be authenticated through laboratory testing to ensure that a photograph or x-ray has not been altered in any way. Maps, models, and summaries can be authenticated through expert testimony confirming that they were created using real and reliable evidence gathered from the field at the time of the suspected crime. The American Bar Association has published guidance on the admissibility and proper use of demonstrative aids at trial, underscoring the importance of these authentication steps for legal practitioners.
"Similarities in authentication and chain of custody"
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