How have courts interpreted the confrontation clause in a civil case?

Koach argues that the trial court's conduct of the trial was so unfair that his Sixth Amendment right of confrontation was violated. Questions regarding the admissibility of evidence involving factual determinations, and a court's control over questioning at trial, including restricting cross-examination of a witness, are reviewed for abuse of discretion. United States v. Wood, 943 F.2d 1048, 1055 n. 9 (9th Cir.1991); United States v. Perkins, 937 F.2d 1397, 1405 (9th Cir.1991). Alleged violations of the confrontation clause are reviewed de novo. United States v. George, 960 F.2d 97, 99 (9th Cir.1992).