From Maples v. Thomas:
As we have long recognized, federal habeas review for state prisoners imposes significant costs on the States, undermining not only their practical interest in the finality of their criminal judgments, see Engle v. Isaac, 456 U. S. 107, 126–127 (1982), but also the primacy of their courts in adjudicating the constitutional rights of defendants prosecuted under state law, id., at 128. We have further recognized that “[t]hese costs are particularly high . . . when a state prisoner, through aprocedural default, prevents adjudication of his constitutional claims in state court.” Coleman v. Thompson, 501
U. S. 722, 748 (1991). In that situation, the prisoner has“deprived the state courts of an opportunity to addressthose claims in the first instance,” id., at 732, thereby leaving the state courts without “a chance to mend theirown fences and avoid federal intrusion,” Engle, 456 U. S., at 129. For that reason, and because permitting federalcourt review of defaulted claims would “undercu[t] the State’s ability to enforce its procedural rules,” ibid., we have held that when a state court has relied on an adequate and independent state procedural ground in denying a prisoner’s claims, the prisoner ordinarily may not obtain federal habeas relief. Coleman, 501 U. S., at 729–730.