dissenting.
The majority reverses the jury verdict that found the union in breach of its duty of fair representation. The union was obligated to represent Rupe fairly in the grievance proceeding. Hines v. Anchor Motor Freight, Inc., 424 U.S. 554, 564, 96 S.Ct. 1048, 1056, 47 L.Ed.2d 231 (1976). The union’s representation must not be “arbitrary, discriminatory or in bad faith.” Vaca v. Sipes, 386 U.S. 171, 190, 87 S.Ct. 903, 916, 17 L.Ed.2d 842 (1967). The majority correctly notes that actionable conduct under this standard falls into two distinct categories: even-handed representation (i.e., neither discriminatory nor in bad faith) and diligent *697representation (i.e., neither arbitrary nor perfunctory). Viewed from both perspectives, I would affirm the jury’s verdict.
It is imperative to understand our standard of review in this case. A jury verdict is not lightly set aside; we must affirm it so long as it has any reasonable basis in the record. Wyant v. J. I. Case Co., 633 F.2d 1254, 1256 (7th Cir. 1980). We must review all the evidence in the light most favorable to the prevailing party. Smith v. Rogers, 290 F.2d 601, 602 (7th Cir. 1961). We are not to substitute our judgment for that of the jury, and we cannot usurp the jury’s function as the finder of fact. Collins v. Signetics Corp., 605 F.2d 110, 115 (3d Cir. 1979). In particular, determining the credibility of witnesses and the weight to be accorded testimony are matters peculiarly within the province of the jury. Pinkowski v. Sherman Hotel, 313 F.2d 190, 193 (7th Cir. 1963). I believe that the majority has ignored all of these admonitions.
I
The majority denies that there is sufficient evidence to show that the union harbored animosity towards Rupe. The evidence showed that Hord, the union representative, told Rupe that his grievance was meritless and refused to file it. Hord eventually did file the grievance, but only after Rupe complained to the NLRB. The majority concludes that Hord’s refusal to process the grievance was based upon an honest belief that Rupe could be discharged without cause. This may or may not be true, but it is not our role to make this determination. The jury is to decide what beliefs Hord had, whether they were honestly held, and what motivated his actions. The majority improperly weighs the evidence and draws certain inferences to reach its conclusion that Hord harbored no animosity toward Rupe. Viewing the evidence in the light most favorable to Rupe, a jury could rationally conclude that Hord harbored animosity toward Rupe based upon his refusal to process the grievance until after Rupe complained to the NLRB.
II
The majority also denies that there is sufficient evidence of arbitrary and perfunctory conduct by the union in its processing of Rupe’s grievance. Nonetheless, the evidence showed that the union (1) failed to argue that article 46 of the collective bargaining agreement (which prohibited Spector from discharging employees without just cause) applied to Rupe as a casual employee, (2) failed to perform any investigation of the circumstances surrounding Rupe’s discharge, (3) failed to prepare a written presentation for the grievance committee, and (4) failed to argue that Rupe’s second waiver was invalid because it was executed involuntarily.
The majority attempts to show that Hord had a reasonable and honest belief that article 46 of the collective bargaining agreement did not cover Rupe, and so his failure to perform all these actions was understandable. Perhaps it was. Determining what Hord honestly believed about the contract, however, is a matter for the jury. Similar remarks apply to the majority’s analysis of the other failures to act. These omissions may seem reasonable to the majority; but we are not the trier of fact. We do not determine credibility, weigh the evidence, or substitute our judgment for that of the jury. Our job is to determine whether there was any reasonable basis in the record for the jury’s verdict. If the evidence is viewed in the light most favorable to Rupe (as we must), the union’s failure to act in these four ways is sufficient to support the jury’s verdict. Our scope of review extends no further.
It is undisputed that the union processed Rupe’s grievance only after he filed a charge with the NLRB, failed to investigate the circumstances surrounding Rupe’s discharge, prepared no written statement for the grievance committee, and failed to raise two arguable defenses on Rupe’s behalf. I do not understand how the majority can say that no reasonable jury could conclude on the basis of these facts that the union failed to meet its duty of fair representation. See Miller v. Gateway Transportation Co., 616 F.2d 272, 277 (7th Cir. 1980).
*698I concur in Part II of the majority’s opinion. For this reason, I would affirm the judgment in favor of Rupe against Spector, and reverse and remand for entry of judgment in favor of Rupe against the union.