Evidence of the bias or interest of a witness is admissible to impeach the credibility of the witness.

United States v. Adefehinti, 510 F.3d 319, 326-327 (D.C. Cir. 2007) (upholding trial court's admission of loan documents [which were based on certificates provided by the records' custodians] as business records exception....There is a hearsay exception for a memorandum, report, record, or data compilation, in any form, of acts, events, conditions, opinions, or diagnoses, made at or near the time by, or from information transmitted by, a person with knowledge, if kept in the course of a regularly conducted activity of a business, institution, association, profession, occupation, or calling if it was the regular practice of that business, institution, association, profession, occupation, or calling to make the memorandum, report, record or data compilation, unless the source of information or the method or circumstances of preparation indicate lack of trustworthiness.

United States v. Hadley, 918 F.2d 848, 851 (9th Cir. 1990) (upholding trial court's admission of witnesses' testimony about accused's prior sexual abuse acts because similarities of the prior acts to the offense charged were sufficient to show accused's intent ).Federal Rule of Evidence 414 and comparable rules in a few States create an exception to the prohibition against "circumstantial" use of character -- the prohibition against the use of character to show conduct -- by providing that in a criminal trial for child molestation or child sexual abuse, evidence of the defendant's commission of another offense or offenses of child molestation or child sexual abuse is relevant and admissible.

Delaware v. Van Arsdall, 475 U.S. 673, 678-679 (1986) (dictum: "The Confrontation Clause of the Sixth Amendment guarantees the right of an accused in a criminal prosecution 'to be confronted with the witnesses against him.' The right of confrontation, which is secured for defendants in state as well as...The trial court has broad discretion to bar abusive, humiliating, and harassing questions.