Here is an interesting case from the Tenth, about cross-examination of a witness about a prior judicial “finding” that the witness was not credible — United States v. Woodard.
The court states this basic principle from its own jurisprudence:
The Sixth Amendment guarantees the right of a defendant to “be confronted with the witnesses against him.” U.S. Const. amend. VI. One of the primary interests secured by the Sixth Amendment’s confrontation clause is the right of cross-examination. Davis v. Alaska, 415 U.S. 308, 315 (1974). This is the“principal means by which the believability of a witness and the truth of his testimony are tested.” Id. at 316. A violation of this constitutional right occurs when “the defendant is prohibited from engaging in otherwise appropriate cross-examination that, as a result, precludes him from eliciting information from which jurors could draw vital inferences in his favor.” United States v. Montelongo, 420 F.3d 1169, 1175 (10th Cir. 2005) (internal quotation marks omitted). Stated differently, “‘a defendant’s right to confrontation may be violated if the trial court precludes an entire relevant area of cross-examination.’” Id. (quoting Parker v. Scott, 349 F.3d 1302, 1316 (10th Cir. 2005)).