Does the collateral estoppel effect apply to the finding of probable cause in a federal traffic trial?

3 We note that, even if that issue had been decided in magistrate's court, its preclusive effect would be weak. Although Arizona courts have applied the collateral estoppel effects of convictions in magistrate's court on the issue of probable cause, they have been less willing to give full preclusive effect to the results of magistrate trials involving, as here, civil traffic offenses. "Collateral estoppel effect is generally denied to traffic convictions and minor offenses under accepted common law principles." State v. Walker, 768 P.2d 668, 671 (Ariz.App.1989). The Arizona court reasoned the collateral estoppel effect of such proceedings was weaker because the lower stakes in such proceedings do not provide an incentive for the parties to litigate "with the same vigor," and because the statutory scheme for such trials requires them to be informal, "quasi-administrative" proceedings, without many of the protections and procedural rules of full trials. Id. at 671-672. Thus we are not convinced the federal district court would have been obligated to give full preclusive effect in federal court to the determinations of the municipal magistrate in civil traffic court.