Real and Demonstrative Evidence
There are four types of evidence in a legal trial: real, demonstrative, documentary and testimonial. For a discussion of the first two types of evidence, along with a discussion of when this evidence is admissible in trial, read on.
Real evidence, often called physical evidence, consists of material items involved in a case, objects and things the jury can physically hold and inspect. This kind of evidence is usually admitted because it tends to prove or disprove an issue of fact in a trial. Real evidence is usually involved in an event central to the case, such as a murder weapon, clothing of a victim, narcotics or fingerprints.
Real evidence must be relevant, material, and authentic before a judge will permit its use in a trial. The process whereby a lawyer establishes these basic prerequisites is called laying a foundation, accomplished by calling witnesses who establish the item's chain of custody.
Demonstrative evidence, usually charts and diagrams, demonstrates or illustrates the testimony of a witness. It is admissible when it fairly and accurately reflects the witness's testimony and is more probative than prejudicial. Maps, diagrams of a crime scene, charts and graphs that illustrate physical or financial injury to a plaintiff are examples of demonstrative evidence. Witnesses create and use demonstrative evidence at trial, and opposing counsel may use the same evidence to prove contrary positions.
Admissibility of Evidence
The admissibility of real and demonstrative evidence depends on more than authenticity and materially. In addition, the evidence's probative value must not be outweighed by the sheer shock value, or prejudicial value, of the evidence.
For example, a photograph of a murder victim would be admissible to show whether the defendant could have inflicted the wounds visible in the photograph. Conversely, photographs of what the body looked like after a week of rigor would be inadmissible, as they would have little probative value and would be highly prejudicial due to shock value.
Is the Evidence More Probative Than Prejudicial?
The difficult admissibility questions arise when the probative value is low, the prejudicial value is high, but the law requires the People (or the plaintiff) to use the evidence to prove an element of a charge. For example, if a defendant in a criminal case takes the witness stand to testify in his own defense, Federal Evidentiary Rule 609 allows the Government to impeach the defendant's testimony with evidence of prior bad acts. These bad acts may include prior convictions, including convictions for crimes just like the one the defendant is currently be on trial for. After hearing about these bad acts, juries may no longer be able to keep an open mind.
So what's a judge to do? Under the federal rules, relevant evidence is to be excluded if "its probative value is substantially outweighed by the danger of unfair prejudice." Similarly, Federal Rule 352 allows for exclusion to avoid "substantial danger of undue prejudice."
Questions About Real and Demonstrative Evidence? Talk to an Attorney
Gathering real evidence and collecting testimonial evidence is never easy, but it often depends on a good defense attorney to gather the right investigators and to lay the proper foundation at trial. If you are being investigated for a crime and may be headed to trial, it's in your best interest to consult with a criminal defense attorney in your area.