A statement by a co-conspirator of a party is not barred by the hearsay rule from being admitted against the party if the statement was made by the co-conspirator during the course and in furtherance of the conspiracy.

Perrin v. Anderson, 784 F.2d 1040, 1043-1045 (10th Cir. 1986) (holding, in a civil rights action against defendant highway patrolmen, that "the testimony recounting [decedent's] previous violent encounters with police officers was admissible as evidence of a habit" as it established that...The habit of a natural person is admissible to show the person's conduct on a particular occasion.

United States v. Floyd, 343 F.3d 363, 368 (5th Cir. 2003) (upholding trial court's admission into evidence of the staged Houston and Los Angeles accidents because there was sufficient evidence to show that the accidents involved the accused and that they were staged).Evidence of another crime, wrong, or act is admissible if there is sufficient evidence to support a finding by a reasonable juror that the other crime, wrong, or act occurred. Clear and convincing evidence is unnecessary; "sufficient" means only that there must be enough evidence to make the other crime, wrong, or act relevant.

United States v. Gomez, 807 F.2d 1523, 1527 (10th Cir. 1986) (trial court has broad discretion to find witnesses to be incompetent).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.