In Campbell-Ewald Co. v. Gomez, 2016 WL 228345, at *1 (U.S.,2016), the SCOTUS held that:

An unaccepted settlement offer or offer of judgment does not moot a plaintiff’s case, so the District Court retained jurisdiction to adjudicate Gomez’s complaint.Article III’s “cases” and “controversies” limitation requires that “an actual controversy … be extant at all stages of review, not merely at the time the complaint is filed,” Arizonans for Official English v. Arizona, 520 U.S. 43, 67, 117 S.Ct. 1055, 137 L.Ed.2d 170 (internal quotation marks omitted), but a case does not become moot as “long as the parties have a concrete interest, however small,” in the litigation’s outcome, Chafin v. Chafin, 568 U.S. ––––, –––– (internal quotation marks omitted).  Gomez’s complaint was not effaced by Campbell’s unaccepted offer to satisfy his individual claim. Under basic principles of contract law, Campbell’s settlement bid and Rule 68 offer of judgment, once rejected, had no continuing efficacy. With no settlement offer operative, the parties remained adverse; both retained the same stake in the litigation they had at the outset.