lysis with the rec- ognition that "[p]ast exposure to illegal conduct does not in itself show a present case or controversy" for equitable relief. OShea v. Littleton, 414 U.S. 488, 495, 94 &Ct. 669, 675, 38 L.Ed.2d 674 (1974) (0Shea). Claims for equitable relief there- fore become moot when the chal