Evidence (law)

The 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).

Relevance and related social policy concerns

In every jurisdiction based on the English common law tradition, evidence must conform to a number of rules and restrictions to be admissible. Evidence must be relevant — that is, it must have a tendency to make a fact at issue in the proceeding be more or less probable than it would be without the evidence.

However, relevance is ordinarily a necessary condition but not a sufficient condition for the admissibility of evidence. For example, relevant evidence may be excluded if it is unfairly prejudicial, confusing, or cumulative. Furthermore, a variety of social policies operate to exclude relevant evidence. Thus, there are limitations on the use of evidence of liability insurance, subsequent remedial measures, settlement offers, and plea negotiations, mainly because it is thought that the use of such evidence discourages parties from carrying insurance, fixing hazardous conditions, offering to settle, and pleading guilty to crimes, respectively.

Presence or absence of a jury

Of all jurisdictions worldwide, the United States of America has the most complicated system of evidentiary rules. The unusual complexity of American evidence law arises from two factors: (1) the right of American defendants to have findings of fact made by a jury in practically all criminal cases as well as many civil cases; and (2) the widespread consensus that tight limitations on the admissibility of evidence are necessary to prevent a jury of untrained laypersons from being swayed by irrelevant distractions (such as the infamous Chewbacca Defense). Legal historian Lawrence Friedman has explained that "^* trained judge would not need all these rules; and indeed, the law of evidence in systems that lack a jury is short, sweet, and clear."

Authentication

Certain kinds of evidence, such as documentary evidence, may be subject to further restrictions such as the best evidence rule, which requires certain documents to be produced unless they can shown to be unavailable.

Witnesses

In systems of proof based on the English common law tradition, almost all evidence must be sponsored by a witness, who has sworn or solemnly affirmed to tell the truth. The bulk of the law of evidence regulates the types of evidence that may be sought from witnesses and the manner in which the interrogation of witnesses is conducted during direct examination and cross-examination of witnesses. Other types of evidentiary rules specify the standards of persuasion (e.g., proof beyond a reasonable doubt) that a trier of fact such as a jury must apply when it assesses evidence.

Today all persons are presumed to be qualified to serve as witnesses in trials and other legal proceedings, and all persons are also presumed to have a legal obligation to serve as witnesses if their testimony is sought. However, legal rules sometimes exempt people from the obligation to give evidence and legal rules disqualify people from serving as witnesses under some circumstances.

Privilege rules give the holder of the privilege a right to prevent a witness from giving testimony. These privileges are ordinarily (but not always) designed to protect socially valued types of confidential communications. Some of the privileges that are often recognized are the marital secrets privilege, the adverse spousal testimony privilege, the attorney-client privilege, the doctor-patient privilege, the psychotherapist-patient and counselor-patient privilege, and the clergy-penitent privilege. A variety of additional privileges are recognized in different jurisdictions, but the list of recognized privileges varies from jurisdiction to jurisdiction; for example, some jurisdictions recognize a social worker-client privilege and other jurisdictions do not.

Witness competence rules are legal rules that specify circumstances under which persons are ineligible to serve as witnesses. For example, neither a judge nor a juror is competent to testify in a trial in which they are serving in that capacity; and in jurisdictions with a dead man statute, a person is deemed not competent to testify as to statements of or transactions with a deceased opposing party.

Hearsay

Hearsay is one of the largest and most complex areas of the law of evidence. The default rule is that hearsay evidence is inadmissible. Hearsay is an out of court statement offered to prove the truth of the matter asserted. A party is offering a statement to prove the truth of the matter asserted if the party is trying to prove that the assertion made by the declarant (the maker of the pretrial statement) is true. For example, prior to trial Bob says, "Jane went to the store." If the party offering this statement as evidence at trial is trying to prove that Jane actually went to the store, the statement is being offered to prove the truth of the matter asserted. However, at both common law and under evidence codifications such as the Federal Rules of Evidence, there are dozens of exemptions from and exceptions to the hearsay rule. One common exception is the voir dire from a police officer, which is generally excepted in trial.

Burdens of proof

Different types of proceedings require parties to meet different burdens of proof, the typical examples being reasonable doubt, clear and convincing, and preponderance of the evidence. Many jurisdictions have burden-shifting provisions, which require that if one party produces evidence tending to prove a certain point, the burden shifts to the other party to produce superior evidence tending to disprove it.

One special category of information in this area includes things of which the court may take judicial notice. This category covers matters that are so well known that the court may deem them proven without the introduction of any evidence. For example, if a defendant is alleged to have illegally transported goods across a state line by driving them from Boston to Los Angeles, the court may take judicial notice of the fact that it is impossible to drive from Boston to Los Angeles without crossing a number of state lines. In a civil case, where the court takes judicial notice of the fact, that fact is deemed conclusively proven. In a criminal case, however, the defense may always submit evidence to rebut a point for which judicial notice has been taken.

Evidentiary rules stemming from other areas of law

Some rules that affect the admissibility of evidence are nonetheless considered to belong to other areas of law. These include the exclusionary rule of criminal procedure, which prohibits the admission in a criminal trial of evidence gained by unconstitutional means, and the parol evidence rule of contract law, which prohibits the admission of extrinsic evidence of the contents of a written contract.

Evidence as an area of study

Because of its importance to the practice of law, all American law schools offer a course in evidence, and most require the subject either as a first year class, or as an upper-level class, or as a prerequisite to later courses. Furthermore, evidence is heavily tested on the Multistate Bar Examination ("MBE") - of the 200 multiple choice questions asked in that test, approximately one sixth will be in the area of evidence. The MBE tests evidence predominately under the Federal Rules of Evidence, giving little attention to matters for which state law is likely to be inconsistent.

References

Lawrence M. Friedman, American Law in the Twentieth Century (New Haven: Yale University Press, 2002), 266.

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