464 U.S. 154 (1984)
In 1978 respondent Sergio Mendoza, a Filipino national, filed a petition for naturalization under a statute which by its terms had expired 32 years earlier.1 Respondent’s claim for naturalization was based on the assertion that the Government’s administration of the Nationality Act denied him due process of law.2 Neither the District Court nor the Court of Appeals for the Ninth Circuit ever reached the merits of his claim.3 They held that the Government was collaterally estopped from litigating that constitutional issue in view of an earlier decision against the Government in a case brought by other Filipino nationals in the United States District Court for the Northern District of California.4
The facts bearing on respondent’s claim to naturalization are not in dispute.5 In 1942 Congress amended the Nationality Act.6 Section 701 of the Act provided that noncitizens who served honorably in the Armed Forces of the United States during World War II were exempt from some of the usual requirements for nationality.7 In particular, such veterans were exempt from the requirement of residency within the United States and literacy in the English language.8 Congress later provided by amendment that all naturalization petitions seeking to come under § 701 must be filed by December 31, 1946.9
Respondent Mendoza served as a doctor in the Philippine Commonwealth Army from 1941 until his discharge in 1946.10 Because Japanese occupation of the Philippines had made naturalization of alien servicemen there impossible before the liberation of the Islands, the INS did not designate a representative to naturalize eligible servicemen there until 1945.11 Because of concerns expressed by the Philippine Government to the United States, however, to the effect that large numbers of Filipinos would be naturalized and would immigrate to the United States just as the Philippines gained their independence, the Attorney General subsequently revoked the naturalization authority of the INS representative.12 Thus all naturalizations in the Philippines were halted for a 9-month period from late October 1945 until a new INS representative was appointed in August 1946.13
Respondent’s claim for naturalization is based on the contention that that conduct of the Government deprived him of due process of law in violation of the Fifth Amendment to the United States Constitution.14 He was present in the Philippines during part, but not all, of the 9-month period during which there was no authorized INS representative there.15 The naturalization examiner recommended denial of Mendoza’s petition.16 The District Court granted the petition without reaching the merits of Mendoza’s constitutional claim.17 The District Court concluded that the Government could not relitigate the due process issue because that issue had already been decided against the Government in In re Naturalization of 68 Filipino War Veterans, 406 F. Supp. 931 (ND Cal. 1975), a decision which the Government had not appealed.18
Noting that the doctrine of nonmutual offensive collateral estoppel has been conditionally approved by this Court in Parklane Hosiery Co. v. Shore, 439 U. S. 322 (1979), the Court of Appeals concluded that the District Court had not abused its discretion in applying that doctrine against the United States in this case.19 The Court of Appeals rejected the Government’s argument that Parklane Hosiery should be limited to private litigants.20 Although it acknowledged that the Government is often involved in litigating issues of national significance where conservation of judicial resources is less important than “getting a second opinion,” it concluded that litigation concerning the rights of Filipino war veterans was not such a case.21 The Supreme Court granted certiorari to review the judgment of the Court of Appeals.22
Whether the United States may be collaterally estopped on an issue adjudicated against it in an earlier lawsuit brought by a different party?23
Under the judicially developed doctrine of collateral estoppel, once a court has decided an issue of fact or law necessary to its judgment, that decision is conclusive in a subsequent suit based on a different cause of action involving a party to the prior litigation.24 Collateral estoppel serves to relieve parties of the cost and vexation of multiple lawsuits, conserve judicial resources, and encourage reliance on adjudication by preventing inconsistent decisions.25 The Government is not in a position identical to that of a private litigant, both because of the geographic breadth of Government litigation and also, most importantly, because of the nature of the issues the Government litigates, which frequently involve questions of substantial public importance that can arise only in suits to which the Government is a party.
No. The prior adjudication in In re Naturalization of 68 Filipino War Veterans involved other Filipino nationals and did not include Mendoza as a party to that litigation.26 The Government participates in far more cases nationwide than any private entity, including more than 75,000 of the 206,193 district court filings in 1982.27 Many constitutional questions arise only in Government litigation.28 Application of nonmutual offensive collateral estoppel would freeze development of the due process issue concerning the nine-month halt in Philippine naturalizations.29
It would deprive the Supreme Court of the benefit of multiple courts of appeals exploring the question.30 It would also force the Solicitor General to abandon prudential considerations such as limited resources and crowded dockets by appealing every adverse decision.31
The United States may not be collaterally estopped on an issue adjudicated against it in an earlier lawsuit brought by a different party.32