Admissibility or inadmissibility of other crimes, wrongs, or acts

United States v. Blankenship, 923 F.2d 1110, 1116-1117 (5th Cir. 1991) (trial court has broad discretion to declare witnesses to be incompetent but trial court did not abuse its discretion in ruling that the challenged witness was competent).It is possible that persons may be disqualified from serving as witnesses on grounds not expressly enumerated in codes of evidence or by general common law principles -- on unenumerated grounds such as age, illness, sensory defects, defects in intelligence, lack of understanding, inability to communicate, defects in memory, and inability to be truthful.

United States v. Butterworth, 511 F.3d 71, 74-75 (1st Cir. 2007) (upholding trial court's admission of grand jury testimony of defendant's girlfriend to cross-examine her after she gave testimony that was inconsistent with....A prior inconsistent statement is exempt from the federal hearsay rule pursuant to Federal Rule of Evidence 801(d)(1)(A) or by a comparable State rule only if the prior statement is in fact inconsistent with the declarant's testimony at the trial or with some other statement of the declarant that is admitted into evidence pursuant to some hearsay exemption or exception.

Makuc v. American Honda Motor Co., 835 F.2d 389, 391-392 (1st Cir. 1987) (holding, in plaintiff injured motorbike rider's action against defendant manufacturer for product liability, that wtinesses' testimony [on what the mechanic....To qualify as a statement of present sense impression for purposes of the hearsay exception by that name, the statement made by the declarant (the maker of the statement) must describe or explain an event or condition.