claim that Elzy had ineffective assistance of counsel was never objected to in the § 2255 proceedings, and has not been brought before us either. We also note that the Government failed to raise Elzy’s default, either before the district court or before us on appeal. But we are not required to review the merits of defaulted claims simply because the Government has failed to raise the issue. While procedural default is not a jurisdictional bar to review of such a claim, see Trest v. Cain, 522 U.S. 87, 118 S.Ct. 478, 480, 139 L.Ed.2d 444 (1997), and the Government’s failure to raise the default may operate as a forfeiture of its right to defend on that ground, see id, we nonetheless may raise these issues sua sponte. See Rosario v. United States, 164 F.3d 729, 732-33 (2d Cir.1998) (<HOLDING>); Hines v. United States, 971 F.2d 506, 508
holding that a district court has the discretion to raise a  2254 timeliness consideration sua sponte holding that a state appellate courts decision to raise and answer a constitutional question sua sponte permits subsequent federal habeas review holding that because concerns of finality of criminal judgments judicial economy and orderly administration of justice substantially implicate important interests beyond those of the parties appellate court may raise frady defense sua sponte holding that the court can raise res judicata sua sponte even on appeal holding that appellate court may raise issues of default sua sponte where necessary to protect inter alia the finality of federal criminal judgments