how- ever, on the defendant to show that there is no reasonable expectation of repetition. United States v. W.T. Grant Co., 345 U.S. 629, 633, 73 S.Ct 894, 897, 97 LEd. 1308 EFTA00191842 OLAGUESI cite es (1953) (W.T. Grant). Voluntary cessation of the challenged activity by the official is insuff