Evidence establishes facts. For instance, the evidence of a bloody fingerprint would help to establish the fact that a certain person was at the scene of the victim's murder. Real and demonstrative evidence are two important forms of evidence, but they can be only used at trial if they're admissible and relevant.
Evidence: Definition and Types
Evidence is used at trials to prove or disprove certain facts that would tend to show whether something was true or not. There are four types evidence by which facts can be proven or disproven at trial which include:
Not all of these types of evidence carry the same weight at trial. For instance, real evidence may be more believable than demonstrative evidence. It's the jury's role to weigh each type of evidence and make a determination as to the believability of the evidence presented.
Real evidence, often called physical evidence, consists of material items involved in a case, objects and things the jury can physically hold and inspect. Examples of real evidence include fingerprints, blood samples, DNA, a knife, a gun, and other physical objects.
Real 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.
In order to be used at trial, real evidence must be relevant, material, and authentic. 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, demonstrate or illustrate the testimony of a witness. It's 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.
The production of documents at trial is documentary evidence which is presented to prove or disprove certain allegations at trial. These documents can be from a vast number of sources from diaries, letters, contracts, newspapers, and any other type of document that you can think of. There are restrictions and qualifications for using documents at trial as there is a need to make sure they are authentic and trustworthy.
When a person gets up on the stand at trial and relates something that they saw or heard, that is testimonial evidence. It is simply a witness giving testimony under oath about the facts of the case.
Admissibility of Evidence
Evidence cannot be used at trial unless it's admissible. The admissibility of evidence depends on more than authenticity and materiality. In addition, the probative value of the evidence (it's ability to prove or disprove facts) 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 mortis 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 Rule of Evidence 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 403 allows for exclusion to avoid "substantial danger of undue prejudice."
More 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're 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.