Witnesses are persons who come to court and swear under oath to give truthful testimony. The person deposes before the court his/her knowledge regarding the facts of an issue between parties to a cause. Generally, every person is considered competent to be a witness.
A person should only testify to those facts that the person knows first hand. Evidence should not be given of facts that are beyond the personal knowledge of the person. The witness will be declared incompetent and the testimony will be excluded if on cross-examination it appears that a witness does not know about the facts of the case that s/he testified.
When two witnesses have the equal means to have knowledge about a fact, they are equally competent to be witnesses in a case[i]. This is true even if one of the witness had imperfectly comprehended the fact but faintly recollects the transaction, and the other person is clear about the matter and perfect in his/her recollection. Even if the person had acquired knowledge about a fact in an unlawful manner, the witness will be considered competent[ii]. Despite having knowledge of the pertinent facts, if a witness possesses some bias in favor of one litigant, the person will be considered as a competent witness.
In courts, negative testimony is admissible. This is possible where the attending circumstances show that it has some probative force. However, the competency of the witness and his/her knowledge of the matter should be established. A witness is considered competent to testify about the absence of a thing or the nonappearance of a matter when it can be proved that the person was in a position to see and hear the thing inquired about. A witness who had the opportunity of seeing or hearing certain facts can testify about the non-ringing of a bell, the non-sounding of a horn, or the failure to blow a whistle or give another signal.
If a person has only heard a part of a conversation, s/he will be competent to testify about that part heard or understood. Although, a witness was not present at the time of commission of a crime, the person can properly testify that individuals depicted on a videotape were the perpetrators of the crime. The testimony can be based on information the person obtained concerning a description of the suspect and the lack of other individuals being identified.
Generally, the evidence provided by witnesses when information is derived from statements or writings of others are excluded. However, there are exceptions to the rule. A bank cashier can testify that a certain person has no bank account although the information is derived from the books of the bank[iii]. A bank officer can testify about transactions from his/her knowledge of its course of business, even if the person has no personal knowledge of them. A pediatrician can testify without objection regarding the examination of the youngest victim in a criminal case involving taking indecent liberties with a child, that there was vaginal trauma statistically consistent with previous penetration.
The testimony of a witness should not be excluded because the witness has a hearing problem[iv]. If the witness’s answers to the questions were responsive, then that person’s evidence need not be excluded. However, the opposing party can request a written charge to the jury that the disability of the witness could be considered as bearing on the weight to be given to the witness’s testimony. Deaf and mute persons are not incompetent witnesses. If they are able to communicate the facts and are of sufficient mental capacity to observe the matters as to which they will testify and to appreciate the obligation of an oath, their evidence will have value. Trial courts have the power to determine the qualifications of a deaf-mute witness to testify and the selection and qualification of the interpreter. If there is any confusion arising from the use of sign language to communicate with a deaf and mute witness it is the weight of the evidence that is questioned and not the admissibility.
Intoxication will not render a witness incompetent, unless the person was virtually unconscious at the time of the event. Persons intoxicated at the time they are offered as witnesses are excluded from testifying. The competency of an intoxicated witness is determined according to the discretion of the court. Drug use also does not render a witness incompetent. However, addiction to drugs can affect the credibility and weight of the person’s testimony.
The fact that a witness is insane or mentally ill does not automatically render a witness incompetent[v]. If the person affected with insanity has sufficient knowledge to apprehend the obligation of an oath and is capable to give a correct account of the matters which the person has seen or heard about the questions at issue, the person can be considered a competent witness. The person should be capable to perceive and narrate. The incapacity of an insane person to be a competent witness should be determined by court. The mental competency of a witness can be ascertained by producing and examining the witness before the court. After the examination, the trial court can exercise discretion to permit the witness to testify. The decision of the trial court will not be disturbed on appeal unless there is a clear abuse of discretion.
The testimony of a convicted felon cannot be considered inadmissible. However, the weight of the evidence can be questioned. However, if state statutes provide that the evidence of a convicted felon cannot be admitted, a convicted felon will be considered am incompetent witness. Some statutes provide that convicted persons can be competent witnesses. Convicts in prison can also be considered competent witnesses. However, perjury offenders cannot be considered competent witnesses. In the federal courts, even a convicted perjurer is competent to testify. In federal cases, the common-law grounds of incompetency including infamy is excluded.
The conviction of a person in one state will not make the person an incompetent witness in another state. Similarly, conviction of a person in a foreign country does not disqualify the witness in a state court of the U.S. A state convict can be a competent witness in a federal court. Conversely, a federal court convict can testify as a witness in a state court.
In most of the states, the general disqualification by interest is excluded. In the federal courts, the Federal Rules of Evidence eliminate all the common-law grounds of incompetency. Interest in the outcome of the litigation is also eliminated in the federal courts. The credibility of the witnesses is determined by the courts or the jury. A party to a case can be a competent witness on their own behalf, or can be compelled to testify for others. The defendant in a criminal case cannot be compelled to be a witness against himself/herself. However, the defendant is entitled to be sworn as a witness and can testify on his/her own behalf. It is the discretion of a trial court to refuse an accused permission to make a statement not under oath. All the rules applicable to an ordinary witness are applicable to a defendant who takes the stand as a witness on his/her own behalf.
According to common law, if a witness has an interest in the outcome of the litigation s/he will be incompetent to testify. However, the interest should be a legal interest that causes the witness to lose or gain as a result of the suit[vi]. A contingent, doubtful, or speculative interest is insufficient to disqualify the witness[vii]. An agent or servant is a competent witness for the principal or master. This rule is not applicable when the latter was sued on account of the negligence of the agent or servant. A person who is to receive a reward for, or upon conviction of, an offender is not on that account considered incompetent.
[i] United States v. Taveras, 585 F. Supp. 2d 327 (E.D.N.Y. 2008).
[ii] NLRB v. Western Clinical Laboratory, Inc., 571 F.2d 457 (9th Cir. 1978).
[iii] Kincaid v. Wade, 196 Kan. 174 (Kan. 1966).
[iv] Geiger v. Pfizer, Inc., 2009 U.S. Dist. LEXIS 34982 (S.D. Ohio Apr. 15, 2009).
[v] Commonwealth v. Ware, 459 Pa. 334 (Pa. 1974).
[vi] Blackwell v. Atkinson, 14 Cal. 470 (Cal. 1859).
[vii] Farrington v. Richardson, 153 Fla. 907 (Fla. 1944).