This entry contains information applicable to United States law only. Any matter of fact that a party to a lawsuit offers to prove or disprove an issue in the case. A system of rules and standards used to determine which facts may be admitted, and to what extent a judge or jury may consider those facts, as proof of a particular issue in a lawsuit.
Until 1975, the law of evidence was a creature of the common law: evidence rules in most jurisdictions were established by cases rather than by organized, official codifications. Legal scholars long pushed for legislation to provide uniformity and predictability to the evidentiary issues that arise during litigation. Following a lengthy campaign begun by the American Law Institute, which drafted its Model Rules of Evidence in 1942, and the National Conference of Commissioners on Uniform State Rules, which drafted the Uniform Rules of Evidence in 1953, Congress in 1975 adopted the Federal Rules of Evidence. The Federal Rules of Evidence are the official rules in federal court proceedings. Most states now also have codified rules of evidence based on the federal rules. Both state and federal rules of evidence serve as a guide for judges and attorneys so that they can determine whether to admit evidence — that is, whether to allow evidence to be observed by the judge or jury making factual conclusions in a trial.
One important benchmark of admissibility is relevance. Federal Rule of Evidence 402 states, in part, "All relevant evidence is admissible, except as otherwise provided." The goal of this rule is to allow parties to present all the evidence that bears on the issue to be decided, and to keep out all evidence that is immaterial or lacks probative value. Evidence offered to help prove something that is not at issue is immaterial. For example, the fact that a defendant attends church every week is immaterial, and thus irrelevant, to a charge of running a red light. Probative value is a tendency to make the existence of any material fact more or less probable. For instance, evidence that a murder defendant ate spaghetti on the day of the murder would normally be irrelevant because people who eat spaghetti are not more or less likely to commit murder compared with other people. However, if spaghetti sauce was found at the murder scene, the fact that the defendant ate spaghetti that day would have probative value and would thus be relevant evidence.
Witnesses
The most common form of evidence is the testimony of witnesses. A witness can be a person who actually viewed the crime or other event at issue. Or a witness can be a person with other relevant information— someone who heard a dog bark near the time of a murder, saw an allegedly injured plaintiff lifting weights the day after his accident, or shared an office with the defendant and can describe her character and personality. Any competent person can testify as a witness provided the testimony meets other requirements, such as relevancy.
The Federal Rules of Evidence contain very broad competence requirements. To testify, a witness must swear or affirm that she or he will testify truthfully; possess personal knowledge of the subject matter of the testimony; have the physical and mental capacity to accurately perceive, record, and recollect fact impressions; and possess the capacity to understand questions and communicate understandably, with an interpreter if necessary. When an issue of state law is being determined, the state rules of evidence govern the competency of a witness. States that have not adopted the Federal Rules of Evidence may have other grounds for incompetency, such as mental incapacity, immaturity, religious beliefs, and criminal convictions. The Federal Rules of Evidence and most jurisdictions state that jurors and presiding judges are not competent to testify in the case before them.
To be admissible, testimony must be limited to matters of which the witness has personal knowledge, meaning matters the witness learned about using any of his or her senses. Second, the witness must declare under oath or affirmation that the testimony will be truthful. The purpose of this requirement is to "awaken the witness' conscience and impress the witness' mind with the duty to [be truthful]" (Fed. R. Evid. 603). The oath or affirmation requirement also serves as a ground for perjury if the witness does not testify truthfully. Although the oath frequently invokes the name of God, the witness need not possess any religious beliefs; a secular affirmation is sufficient.
Witnesses may be called to testify by any party to the lawsuit. The party calling a witness to testify generally questions the witness first, in what is known as direct examination. The judge may exercise reasonable control over the questioning of witnesses in order to "(1) make the interrogation and presentation effective for the ascertainment of the truth, (2) avoid needless consumption of time, and (3) protect the witnesses from harassment, or undue embarrassment" (rule 611(a)). Thus, the judge may prevent a witness from rambling in a narrative fashion, and may require an attorney to ask specific questions in order to quickly and effectively ascertain the truth.
The federal rules and most jurisdictions discourage the use of leading questions on direct examination. These are questions designed to elicit a particular answer by suggesting it. For example, the question "Didn't the defendant then aim the gun at the police officer?" is a leading question, and normally would not be permitted on direct examination. By contrast, "What did the defendant do next?" is a nonleading question and would be permitted on direct examination. In most cases, questions that can be answered with either "Yes" or "No" are considered to be leading questions. Courts generally will permit leading questions during direct examination if the witness is adverse or hostile toward the questioning party.
Leading questions are permitted, and are common practice, during cross-examination. Once a party conducts a direct examination, the opposing party is entitled to cross-examine the same witness. The scope of questions asked during cross-examination is limited to the subject matter covered during direct examination, and any issues concerning the witness's credibility. Attorneys use cross-examination for many purposes, including eliciting from a witness favorable facts; having the witness modify, explain, or qualify unfavorable versions of disputed facts elicited during direct examination; and impeaching, or discrediting, the witness.
If a witness is a lay witness (not testifying as an expert), the witness generally may testify as to facts and not as to opinions or inferences, unless the opinions or inferences are "(a) rationally based on the perception of the witness and (b) helpful to a clear understanding of the witness' testimony or the determination of a fact in issue" (rule 701). For example, a witness may not testify that she smelled marijuana unless she can sufficiently establish that she knows what marijuana smells like. Lay witnesses commonly testify about such things as the speed a car was going or someone's approximate age, but these types of inferences are less likely to be permitted the more closely they address critical issues in the case.
"If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise" (rule 702). The admissibility of expert testimony hinges on whether such testimony would help the judge or jury, and whether the witness is properly qualified as an expert. Expert witnesses may, and usually do, testify in the form of an opinion. The opinion must be supported by an adequate foundation of relevant facts, data, or opinions, rather than conjecture. Thus, an expert frequently relies on firsthand or secondhand observations of facts, data, or opinions perceived prior to trial, or presented at trial during testimony or during a hypothetical question posed by an attorney. Courts do not require experts to have first- hand knowledge of facts, data, or opinions because experts in the field do not always rely on such firsthand knowledge. For instance, physicians routinely make diagnoses based on information from several sources, such as hospital records, X-ray reports, and opinions from other physicians.
When an expert offers a scientific fact as substantive evidence or as the basis of his or her opinion, the court must determine the reliability of the scientific fact by looking at such things as the validity of the underlying scientific principle, the validity of the technique applying that principle, adherence to proper procedures, the condition of instruments used in the process, and the qualifications of those who perform the test and interpret the results. Issues frequently arise over such scientific tools and techniques as lie detectors, DNA testing, and hypnosis. Some scientific tests, such as drug tests, radar, and paternity blood tests, generally are accepted as being reliable, and their admissibility may be provided for by statute. See also DNA evidence; forensic science; polygraph.
Hearsay
The credibility of any witness's testimony depends upon three factors: (1) whether the witness accurately perceived what she or he described, (2) whether the witness retained an accurate memory of the perception, and (3) whether the witness's narration accurately conveys the perception. To be allowed to testify, the witness generally must take an oath, must be personally present at the trial, and must be subjected to cross-examination. These conditions promote the factors that lend themselves to the witness's credibility. The rule against hearsay further bolsters the oath, personal presence, and cross-examination requirements.
Hearsay is a statement, made out of court, offered in court to prove the truth of the matter asserted. The statement may be oral or written, or it may be nonverbal conduct intended as an assertion, such as pointing to a crime suspect in a police lineup. The act of pointing in response to a request for identification is the same as stating, "He did it." Not all nonverbal conduct is intended as an assertion, of course. For example, a person usually opens an umbrella to stay dry, not to make the assertion, "It is raining."
Sometimes, statements made out of court are not hearsay because they are not offered for the purpose of proving what they assert. For example: A man who claims that a collision between his car and a truck rendered him unconscious files a lawsuit against the truck driver for negligence. The truck driver wishes to introduce as evidence a statement the man made seconds after the accident: "I knew I should have gotten my brakes fixed; they haven't been working for weeks!" If the purpose of offering the statement is only to prove that the man was conscious and talking following the accident, the statement is not hearsay. However, if the statement is offered to prove that the man's brakes were not working and therefore he caused the accident, then the statement is offered for its truth and is hearsay.
The Federal Rules of Evidence state generally that hearsay is not admissible evidence. The reason is that it is impractical, and in most cases simply impossible, to cross-examine the declarant of an out-of-court statement, or to have the declarant take an oath prior to making the statement. Thus, the credibility of an out-of-court statement cannot easily be ascertained. But the hearsay doctrine is extremely complex. Under the federal rules, for example, most admissions of guilt are not considered hearsay and are therefore admissible, even though they might be stated out of court and then offered as evidence. The federal rules list more than twenty-five exceptions to the general hearsay prohibition. These exceptions apply to circumstances believed to produce trustworthy assertions.
Some exceptions to the hearsay rule require that the person who made the statement be unavailable to testify at trial. One example of this is when a person who is mortally wounded makes a statement before dying about the cause of her death. Under this hearsay exception, the victim's statement assigning guilt or causation is made admissible because the victim is not available to testify at trial and the need for the information is given greater weight than the fear that she lied. Some have argued that the dying declaration exception exists at least in part because of the belief that persons would not waste their last breaths to utter a falsehood. One federal court commented, "More realistically, the dying declaration is admitted because of compelling need for the statement, rather than any inherent trustworthiness" (United States v. Thevis, 84 F.R.D. 57 [N.D. Ga. 1979]). This exception proved noteworthy in the October 1995 trial and ultimate conviction of Yolanda Saldivar, accused of gunning down tejana singing star Selena Quintanilla Perez in a Corpus Christi, Texas, motel. Motel employees testified that Selena's last words before collapsing and dying were, "Lock the door! She'll shoot me again!" and "Yolanda Saldivar in Room 158." Saldivar received a sentence of life in prison following her conviction of murdering the twenty-three-year-old recording artist.
Under some circumstances, the availability of the declarant to testify is immaterial. For example, the excited utterance exception to the hearsay rule allows the admission of an out-of-court statement "relating to a startling event or condition made while the declarant was under the stress of excitement caused by the event or condition" (rule 803(2)). The premise for this exception is that excitement caused by the event or condition leaves a declarant without sufficient time or capacity for reflection to fabricate, thus the statement is considered truthful. An example of an admissible excited utterance is the statement, "Look out! That green truck is running a red light and is headed toward that school bus!" Other examples of hearsay exceptions include statements of medical diagnosis, birth and marriage certificates, business records, and statements regarding a person's character or reputation.
Authentication and Identification
Evidence is not relevant unless its authenticity can be demonstrated. A letter in which the defendant admits her guilt in a tax fraud trial is inadmissible unless the prosecution can first show that the defendant actually wrote it. Bloodstained clothing is irrelevant without some connection to the issues of the trial, such as evidence that the clothing belonged to the accused murderer. The process of linking a piece of evidence to a case — of authenticating or identifying the evidence — is frequently referred to as laying a foundation. Under the Federal Rules of Evidence, a foundation is sufficient if a reasonable juror would find it more probably true than not true that the evidence is what the party offering it claims it to be.
The most basic way to lay an evidentiary foundation is to demonstrate that a witness has personal knowledge. For example, the witness may testify that he wrote the letter, or saw the plaintiff sign the contract, or found the bullet in the kitchen. When the evidence is an object, the witness must testify that the object introduced at the trial is in substantially the same condition as it was when it was witnessed.
Objects that are not readily identifiable must often be authenticated through chain-of-command testimony. In the case of a blood sample, a proper foundation would include testimony from each individual who handled the blood — from the nurse who drew the blood, to the lab technician who tested it, to the courier who delivered it to the courthouse for trial. Unless each individual can testify that the blood sample's condition remained substantially the same from the time it was drawn until the time it was offered as evidence (accounting for any loss in amount due to testing), the court could sustain an objection from the other side. The sample would then be inadmissible for lack of authentication.
Under the Federal Rules of Evidence, some evidentiary items are self-authenticating and need no additional authentication before being admitted. Documents containing the official seal of a government unit within the United States, and certified copies of public records such as birth certificates, are self-authenticating, as are newspapers and congressional documents.
Best-Evidence Rule
Best-evidence rule is a misleading name for the courts' preference for original writings, recordings, and photographs over copies when their contents are sought to be proved. The purpose of this rule at common law was to avoid the potential for inaccuracies contained in handmade copies. The current rule contained in the Federal Rules of Evidence requires the use of original writings, recordings, and photographs (including X rays and motion pictures), but the rule defines original to include most photocopies or prints from the same negative. The risk of inaccuracies from these types of duplicates is almost nonexistent. When the original evidence is lost, destroyed, not obtainable, or in the possession of the opponent, the court will not require a party to produce the original.
Judicial Notice
Some matters relevant to a trial are so obvious that a court will not require evidence to prove them — for example, that it is dark outside at midnight or that April 30, 1995, fell on a Sunday. To prevent wasting a court's time, the rules of evidence permit courts to take judicial notice of such matters, that is, to accept them as true without formal evidentiary proof. Courts may take judicial notice of facts generally known to be true (e.g., that gasoline is flammable) or facts verifiable from dependable sources (e.g., that Des Moines, Iowa, is in Polk County, which can be verified on a map). As a matter of course, courts judicially notice the contents of laws of and within the United States.
Privileges
It is a basic tenet in U.S. jurisprudence that "the public … has a right to every [person's] evidence," and parties in litigation should avail themselves of all rational means of ascertaining truth (Trammel v. United States, 445 U.S. 40, 100 S. Ct. 906, 63 L. Ed. 2d 186 [1980]). Yet courts view certain interests and relationships to be of such importance that they protect those interests and relationships from certain efforts to gather evidence. These protections, or exclusions from the general rule of free access to evidence, are known as privileges.
Federal courts recognize several types of privileges. To encourage clients to communicate freely with their lawyers and to fully disclose any information that may enable their lawyers to provide appropriate legal advice, courts allow clients to refuse to disclose and to prevent any other person from disclosing confidential communications made when seeking legal services. This privilege applies to clients' communications with their attorneys and with the attorneys' office staff. It protects only confidential communications, not communications made to friends or acquaintances in addition to an attorney.
The lawyer-client privilege applies to the client, not the lawyer. Thus, the client, but not the lawyer, has the right to waive the privilege and to testify regarding protected communications. The lawyer-client privilege does not terminate even when the lawyer-client relationship does. The privilege does not apply to a client's allegations of a breach of duty by the lawyer.
To promote open communication within marital relationships, the rules of evidence also recognize a marital privilege. In criminal cases, a person has the privilege to refuse to testify against a spouse. This privilege covers only evidentiary matters that would incriminate the nontestifying spouse (the defendant), since other matters are not likely to jeopardize the marriage relationship. The nontestifying spouse does not have the right to assert the privilege; the privilege belongs only to the testifying spouse.
In criminal and civil cases, testimony about any confidential communications between spouses is also afforded a privilege. Either spouse, not just the testifying spouse, may assert this privilege. Unlike the testifying spouse privilege, the confidential communications spousal privilege survives the termination of the marriage by death or divorce — but it does not apply to permanently separated spouses.
Courts also recognize a political vote privilege, a clergy-penitent privilege, and qualified privileges for trade secrets, state secrets, and the identity of an informant. Some courts also recognize a physician-patient privilege, an accountant-client privilege, and a privilege granted to journalists seeking to protect their news sources.
See: Attorney-Client Privilege; Character Evidence; Circumstantial Evidence; Cumulative Evidence; Derivative Evidence; Direct Evidence; Documentary Evidence; Exclusionary Rule; Extrinsic Evidence; Parol Evidence; Privileged Communication.
