In Government of Virgin Islands v. Smith, 445 F.2d 1089, (3d Cir.1971), the court considered the plight of a defendant improperly tried a second time for the same offense where the double jeopardy issue was raised neither below nor on appeal. The court vacated the conviction as a matter of plain error without discussing the waiver issue, other than to note that other courts that had referred to the waiver-rule had gone on to determine the merits of the case. Smith is distinguishable in that the defendant had been found not guilty in the first trial. In United States v. Gunter, 546 F.2d 861 (10th Cir.1976), cert. denied, Gunter v. U.S., 431 U.S. 920, 97 S.Ct. 2189, 53 L.Ed.2d 232 (1977), the court expressed the same view of plain error in this context, although it upheld the conviction on the ground that defendant's double jeopardy rights had not been violated. In United States v. Rivera, 872 F.2d 507 (1st Cir.), cert. denied, Rivera v. U.S., 493 U.S. 818, 110 S.Ct. 71, 107 L.Ed.2d 38 (1989), the court vacated defendant's conviction on one count of an indictment on which he was wrongly subjected to a second trial even though he had raised no objection below, again as a matter of plain error. In reaching that result, the court specifically rejected the waiver argument on the ground that since a constitutional right was involved the waiver had to be " 'voluntary, knowing, and intelligent.' " Rivera, 872 F.2d at 509. Rivera is distinguishable in that the second trial involved a charge that the prosecutor agreed to dismiss during the first trial to get a conviction from the jury on other charges. The same analysis was followed by the court in U.S. v. Jarvis, 7 F.3d 404, 412-13 (4th Cir.1993) cert. denied, Jarvis v. U.S., 510 U.S. 1169, 114 S.Ct. 1200, 127 L.Ed.2d 549 (1994). Jarvis is distinguishable in that it involved a trial of a charge for which defendant had been previously tried and convicted.