See also COMPETENCE.

To be deemed competent to testify, a witness must have personal knowledge of the matters to which he or she will testify.{footnote}FRE 602; United States v. Sorrentino, 726 F.2d 876 (1st Cir. 1984); M.B.A.F.B. Federal Credit Union v. Cumis Ins. Co., 681 F.2d 930 (4th Cir. 1982).  Check United States v. Owens, 789 F.2d 750 (9th Cir. 1986).
State v. Hollingsworth, 337 S.E.2d 674, 677 (N.C. Ct. App. 1985).
See also COMPETENCE.{/footnote}  This means that the witness must have personally observed the matters testified to.{footnote}Phillips v. Emmons, 514 So. 2d 1369, 1371 (Ala. 1987).{/footnote}  Since witnesses who lack personal knowledge generally got their information from the statements of others, the rule excluding hearsay will often apply as well. 

Any dispute over whether the witness in fact has personal knowledge (e.g., was present at the scene of the alleged crime) is matter of conditional relevancy and is for the jury to resolve.{footnote}M.B.A.F.B. Federal Credit Union v. Cumis Ins. Soc., Inc., 681 F.2d 930, 932-33 (4th Cir. 1982); United States v. Owens, 699 F. Supp. 815, 817-18 (C.D. Cal. 1988); Graham, Handbook of Federal Evidence § 602.1; 3 D. Louisell & C. Mueller, Federal Evidence  § 261, at 45 (1979); 3 Weinstein’s Evidence & 602[02].
Burlington Northern Railroad Company v. Hood, 802 P.2d 458, 466 (Colo. 1990) (applying Colo. R. Evid. 104(b) and 602).{/footnote}   See CONDITIONAL RELEVANCY.  The jury’s determination will stand so long as there was sufficient evidence for the jury to decide that the witness had personal knowledge is generally adequate to support such a finding by the jury.

A witness who at one time had personal knowledge but is incapable of remembering the events in question is not a competent witness.{footnote}Me. R. Evid.  601 (b)(4) (a person is disqualified as a witness if the court finds that he or she lacks any reasonable ability to remember matter).{/footnote}