It is well known that most people tend to retain more of what they see than what they hear. This lends to what some see as an advantage for the prosecution, but demonstrative evidence must pass several tests before admission in a trial. First, there are specific rules pertaining to each type of demonstrative evidence. For instance, if presenting a police sketch as evidence, there is a possibility that it may not be admissible because it is ruled to be hearsay. Second, there are rules for demonstrative evidence in general. For instance, an accident reconstruction chart presented as evidence must be necessary in order to demonstrate another piece of evidence, such as oral testimony.
According to an internet article about evidence, ("Demonstrative Evidence", n.d.) foundation rules for demonstrative evidence involve authentication, representational accuracy and identification. The article also states that demonstrative evidence "must pass the 'three hurdles' of admissibility: relevancy; materiality; and competency." ("Demonstrative Evidence", n.d.)
Documentary evidence is another form of evidence used in many trials. It can be described as any evidence presented through a written document. In most cases, this involves a contract or confession. Some of the rules an attorney must consider when using documentary evidence are the rules of parol evidence, best evidence, authentication, and hearsay.
The parol evidence rule states that the terms of the evidence, for instance a written contract, cannot be altered by other evidence showing a change or contradiction to the original contract.
The best evidence rule deals with the originality of the document being offered for admission. If the document being presented for evidence is not the original, in most cases it will not be allowed as evidence. Courts do not usually allow a copy of a document as evidence.
According to an internet encyclopedia, "the best evidence rule states that when the contents of a written document are offered in evidence, the court will not accept a copy or other proof of the document's content in place of the original document unless an adequate explanation is offered for the absence of the original." ("Evidence", n.d.)
Authenticating documentary evidence is very much the same as with real evidence. Some documentary evidence is considered self-authenticated, such as: commercial papers, business records, newspapers, and periodicals. Hearsay rules for documentary evidence are the same as for other evidence presented in a trial.
In a 1964 Texas wrongful death lawsuit involving a collision between a pickup truck and a train, the Texas Supreme Court ruled that a video tape experiment should not have been permitted as demonstrative evidence. According to an article in an online newsletter by attorneys Abraham, Watkins, Nichols, Sorrells, Matthews and Friend, a video made by the plaintiffs attorney in the case, tried to recreate a beam of light, similar to that of a train. The video showed that the light had temporarily obstructed the pickup driver's view of the train crossing. (Agosto and Murray, 2006.)
The case, Fort Worth and Denver Railway vs. Williams, put to the test the use of