Law of Evidence key terms

The logical tendency of an item of evidence to make a fact in issue more or less probable than it would be without that evidence. It is the threshold condition for admissibility, though relevant evidence may still be excluded on other grounds.

The status of evidence that a court will receive and consider. It depends on relevance plus the absence of an exclusionary rule such as hearsay, privilege, or a discretionary unfair-prejudice bar.

A fact that a party must prove or disprove to succeed on a claim or charge, as fixed by the pleadings or indictment. Evidence is relevant only by reference to such facts, not to background matters.

A fact that is not itself in issue and does not directly prove a fact in issue. Courts generally refuse to allow lengthy inquiry into collateral matters, particularly on cross-examination about credit.

The danger that evidence will be misused by the tribunal of fact, for example by arousing hostility or sympathy, or by being given more weight than it deserves. It is weighed against probative value in discretionary exclusion.

The degree to which an item of evidence supports or undermines a fact in issue, taking into account its reliability and the other evidence available. It is the counterweight to prejudicial effect in discretionary exclusion.

A court's power to exclude technically admissible evidence where its probative value is outweighed by unfair prejudice or its admission would compromise the fairness of the trial. The test is not a simple numerical balance.

The obligation of a party to persuade the tribunal of fact of a fact in issue to the required standard. It is distinct from the evidential burden of producing enough evidence to raise an issue.

The persuasive burden: the obligation borne by a party to prove a fact to the required standard or lose on that issue. It is generally fixed by substantive law and does not shift during the trial.

The obligation to adduce sufficient evidence to make an issue live, so that the tribunal of fact may properly consider it. It may shift between parties as the evidence develops.

The degree of persuasion required of the party bearing the legal burden. Criminal cases require proof beyond reasonable doubt; civil cases require proof on the balance of probabilities.

The criminal standard of proof. It requires the tribunal to be satisfied to the point of being sure of guilt, allowing only doubts that a reasonable person would entertain on the evidence.

The civil standard of proof. The party bearing the burden must show that the fact is more likely than not; the tribunal asks whether the proposition is more probable than its negation.

A rule of law that allows a fact to be inferred from proof of a basic fact, or that places the burden on the other party. Presumptions may be rebuttable or irrebuttable.

A witness's legal capacity to give evidence in the proceedings. It depends on the ability to understand questions and give answers that can be understood, judged in light of the witness's age and condition.

Whether a competent witness can be forced by subpoena or summons to attend and testify. Certain categories, such as the accused and the accused's spouse in criminal cases, are protected.

The questioning of a witness by the party who called that witness. Leading questions are generally prohibited, and the witness's account is expected to be complete and coherent.

Questioning of a witness by an opposing party after examination-in-chief. Leading questions are permitted, and the cross-examiner may challenge the witness's credit and put the opposing case.

Questioning of a witness by the calling party after cross-examination. It is confined to matters arising in cross-examination, and leading questions are generally not permitted.

A question that suggests the answer or assumes a disputed fact, such as one framed to be answered yes or no. It is generally barred in examination-in-chief but allowed in cross-examination.

A witness whose evidence is adverse to the party calling them, allowing the court to permit that party to cross-examine the witness and, in some systems, impeach their credit.

The believability of a witness's testimony, assessed by reference to honesty, perception, memory, and consistency. It may be attacked on cross-examination within limits set by the finality principle.

The rule that answers given by a witness on collateral matters in cross-examination are final, and cannot be contradicted by other evidence. Exceptions exist for certain credit matters such as previous convictions.

A trial within a trial held in the absence of the jury to determine a preliminary issue, such as the voluntariness of a confession or the competence of a child witness.

An out-of-court statement offered to prove the truth of the matter stated. It is generally inadmissible because the maker was not sworn and cannot be cross-examined in the proceedings.

Evidence of a statement admitted not for its truth but for the fact that it was made, or to show the maker's state of mind, or to explain conduct. It falls outside the hearsay rule.

A statement or act from which a fact is to be inferred without the maker expressly stating it, for example a gesture or a question. Whether such assertions fall within the hearsay rule is contested.

A recognised category in which out-of-court statements are admissible for their truth, such as dying declarations, public records, or statements in furtherance of a conspiracy.

Statements and acts forming part of the same transaction as the events in issue, admitted because they are so closely connected that they are treated as part of the event itself.

A statement made by a person who believes death is imminent, concerning the cause or circumstances of what they believe to be their death. It is a recognised hearsay exception in many systems.

An utterance made contemporaneously with, or under the immediate pressure of, a startling event, admitted because the stress is thought to exclude fabrication. It is closely related to res gestae.

An out-of-court statement by an accused admitting, expressly or by implication, an element of the offence charged. It is admissible only if shown to be voluntary.

The requirement that a confession be made free from threats, promises, or oppression by persons in authority. If the confession is not voluntary, it is excluded as unreliable.

Harsh or wrongful treatment by those in authority, such as prolonged interrogation, deprivation, or violence, which may render a confession involuntary and inadmissible.

A promise or threat made by a person in authority that causes the accused to confess. An inducement sufficient to raise a reasonable doubt about voluntariness renders the confession inadmissible.

Evidence obtained through unlawful or unfair means, such as an illegal search or a breach of interrogation rules. Its admissibility depends on statutory or discretionary exclusion rules.

The doctrine that evidence derived from an earlier illegality, such as a confession or a search, may itself be tainted and excluded. Its reception varies widely between jurisdictions.

A power to exclude evidence where its admission would have such an adverse effect on the fairness of the proceedings that the court ought not to admit it, often applied to improperly obtained evidence.

Evidence of a person's general disposition or of specific past conduct, offered to show that they acted in conformity with it. In criminal cases it is tightly restricted, especially for the accused's bad character.

Evidence of a party's other acts or misconduct, adduced to show a striking similarity with the conduct in issue. It is admissible only where its probative force outweighs its prejudicial effect.

A tendency or disposition to behave in a particular way, which character or similar fact evidence may be offered to establish. Propensity reasoning is generally forbidden unless a specific exception applies.

Evidence of an accused's law-abiding disposition, which may be relevant to credibility and, in some jurisdictions, to the likelihood of guilt. It may be rebutted by evidence of bad character.

Evidence of what a witness thinks, believes, or infers, rather than what they perceived. Lay opinion is admissible only where it is a convenient way of summarising perceived facts; expert opinion requires specialised knowledge.

Testimony by a witness with specialised knowledge, skill, or experience, admitted to assist the tribunal on matters outside ordinary understanding. The expert's qualifications and the basis of the opinion must be established.

The very question the tribunal of fact must decide, such as whether the accused was negligent. Opinion evidence on the ultimate issue is restricted in some systems but permitted in others.