Understanding Evidence Law and Types of Evidence
 
 

 Understanding Evidence Law and Types of Evidence

Introduction

We will discuss the principles related to the use of evidence in a trial and the types of evidence that can be presented.

 


 

Evidence Law

The law of evidence governs what can be presented in court.  This understanding can be more properly defined and expanded upon as follows: "[t]he law of evidence governs the use of testimony (e.g. oral or written statements, such as an affidavit) and exhibits (e.g. physical objects) or other documentary material which is admissible (i.e. allowed to be considered by the trier of fact, such as jury) in a judicial or administrative proceeding (e.g., a court of law)".  Other terms used to refer to the law of evidence are evidence law (synonym) or Federal Rules of Evidence, defined as "rules governing admission of evidence before U. S. magistrates, and bankruptcy court, and that have been used as a model for rules of evidence by many states" (Blackwell, 2004). 

"The United States of America has the most complicated system of evidentiary rules" in the world.  The reasons for this complexity are twofold.  First, American defendants have the right to a jury trial in the vast majority of criminal cases and in many civil cases.  Second, strict guidelines regarding what evidence can be admitted into a trial keeps the incidents of irrelevant and potentially distracting facts from being introduced, which may confuse a jury and adversely affect the outcome of a trial.

Of the many criteria and rules that govern the admission and use of evidence in a trial, one of the most important is that of relevance.  If the evidence does not relate directly or indirectly to the issue at hand, it should not be admitted as proof for either the prosecution or the defense in the case.  The adjective relevant in this context simply means that the evidence in question is "closely connected or logically related to the matter at hand" (Blackwell, 2004).  Relevant evidence, therefore, is "evidence that is logically connected to the fact it is intended to establish" (Blackwell, 2004).  Other forms of the word, such as "relevance" and "relevancy", are often used interchangeably to refer to evidence that is to be considered for admission in a case.

Relevancy of evidence, however important, is not enough, though.  It is necessary, but it is not the only criteria for the admission of evidence.  "Relevant evidence may be excluded if it is unfairly prejudicial, confusing, or cumulative".  For example, relevant evidence may be excluded if it is inflammatory or based on hearsay.

Numerous limiting social policies can also come into play.  There are constraints on the "use of evidence of liability insurance, subsequent remedial measures, settlement offers, and plea negotiations" due to the belief that use of such evidence "discourages parties from carrying insurance, fixing hazardous conditions, offering to settle, and pleading guilty to crimes, respectively".

In addition to these guidelines, there are some others.  The first is the rule against opinions.  Opinions are just that--someone's personal thought regarding a person, thing, or event.  As such, they cannot be relied upon as solid evidence.  "Parties and witnesses are supposed to testify to specific factual observations, not to opinions" (Bergman and Berman-Barrett, 2005).  Judges have the ability to disallow any observations that seem to be opinion-, rather than fact-based.

Next, evidence rules contain a strong policy against allowing character evidence to be admitted, especially in civil proceedings.  There are some very good reasons for this.  First, allowing parties to discuss each other's character traits would get the trial off-task and potentially lead to many ad-hominem arguments, drawing out the process to interminable lengths.  Second, people do not always act in accordance with their perceived character traits (Bergman and Berman-Barrett, 2005).  Finally, witnesses can greatly misjudge someone's character, calling into question the usefulness and validity of character evidence.

Finally, there are strict rules governing the admission of statements from witnesses not present at the trial.  This is called hearsay.

Types of Evidence

It can perhaps be deduced that there is more than just one type of evidence, each with their own unique characteristics.  Indeed, there are several major types, including: documentary evidence, digital evidence, demonstrative evidence, exculpatory evidence, physical evidence, prima facie evidence, scientific evidence, and testimony.  Each of these is summarized below.

Demonstrative Evidence:  This is a common form of proof, generally having the form of the representation of an object.  Examples include: photographs, videos, sound recordings, x-rays, maps, drawings, graphs, charts, simulations, sculptures, and models, among others.

Digital Evidence:  In recent years, the use of digital evidence in trials has greatly increased.  Simply put, it is any type of proof that can be obtained from an electronic source, such as emails, hard drives, word processing documents, instant message logs, ATM transactions, cell phone logs, and so forth.

Documentary Evidence:  Similar to demonstrative evidence, above, documentary evidence consists of any proof that can be presented in writing (contracts, wills, invoices, etc.).  However, term can technically include any number of media upon which such documentation can be recorded and stored (photographs, recordings, films, printed emails, etc.).

Exculpatory Evidence:  Typically used in criminal cases, this type of evidence is that which favors the defendant, either partially or totally removing their guilt in the case.  In the United States, if the prosecutor or police have found evidence, it is their duty to disclose it to the defendant.  Failure to do so can result in the case being dismissed.

Physical Evidence:  Quite simply, this type of evidence is any proof introduced in the form of a physical object, whether whole or in part.  In criminal proceedings, such evidence might consist of dried blood, fingerprints, a murder weapon, DNA samples, casts of footprints or tires at the scene of the crime, and so forth.

Prima Facie Evidence:  This is "evidence sufficient to establish a claim or defense until rebutted by contrary evidence" (Blackwell, 2004).  In Latin, it literally means "on its first appearance", and such evidence is generally deemed sufficient to prove a particular proposition or fact if it is not refuted by later evidence or argumentation.

Scientific Evidence:  Evidence submitted to the court claiming to be scientific in nature must first conform to generally-accepted principles of the scientific community.  In addition, judges must now insure that such evidence is also reliable (Bergman and Berman-Barrett, 2005).

Testimony:  This is the "spoken evidence given by a witness under oath in court or at a deposition, or written evidence given under oath through an affidavit" (Blackwell, 2004).  Generally, a witness is called forth, solemnly swears to tell the truth under the penalty of perjury.  This is one of the most common forms of evidence in the legal system.
 
 
 
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