State v. Justin Yang, 2006 WI App 48
For Olson: John J. Grau
¶11 Inquiry into a witness’s bias is always material and relevant. State v. Williamson, 84 Wis. 2d 370, 383, 267 N.W.2d 337, 343 (1978) (bias and improper motive of witness are never collateral). John Henry Wigmore has characterized cross-examination as “beyond any doubt the greatest legal engine ever invented for the discovery of truth.” 5 Wigmore, Evidence § 1367 (Chadbourn rev. 1974). Although, as Van Arsdall observes, this does not mean there can be no limits on a defendant’s cross-examination seeking to expose bias, the great engine only has power if the trial court does not apply too-restrictive a governor or, to use an old railroading term, shunt it to a “dead track.” We analyze Yang’s confrontation-denial contention against this background.