Invoking the federal courts jurisdiction based on diversity of citizenship, petitioners alleged in their complaint that they had suffered physical injuries and property damage as a result of an accident in Colombia caused by the negligence of respondent Lamagno, a federal employee. The United States Attorney, acting pursuant to the statute commonly known as the Westfall Act, 28 U.S.C. 2679(d)(1), certified on behalf of the Attorney General that Lamagno was acting within the scope of his employment at the time of the episode. Ordinarily, upon such certification, the employee is dismissed from the action, the United States is substituted as defendant, and the case proceeds under the Federal Tort Claims Act (FTCA). But in this case, substitution would cause the actions demise: petitioners claims arose abroad, and thus fell within an exception to the FTCAs waiver of the United States sovereign immunity. And the United States immunity would afford petitioners no legal ground to bring Lamagno back into the action. See United States v. Smith, 499 U.S. 160. Endeavoring to redeem their lawsuit, petitioners sought court review of the Attorney Generals scope-of-employment certification, for if Lamagno was acting outside the scope of his employment, the action could proceed against him. However, the District Court held the certification unreviewable, substituted the United States for Lamagno, and dismissed the suit. The Fourth Circuit affirmed.

Held:

The judgment is reversed, and the case is remanded.

23 F.3d 402, reversed and remanded.

JUSTICE GINSBURG delivered the opinion of the Court with respect to Parts I, II, and III, concluding that the Attorney Generals Page II scope-of-employment certification is reviewable in court. Pp. 5-17.

(a) As shown by the division in the lower courts and in this case, the Westfall Act is open to divergent interpretation on the question at issue. Two considerations weigh heavily in the Courts analysis. First, the Attorney General herself urges review, mindful that in cases of the kind petitioners present, the incentive of her delegate to certify is marked. Second, when a Government officials determination of a fact or circumstance - for example, "scope of employment" - is dispositive of a court controversy, federal judges traditionally proceed from the strong presumption that Congress intends judicial review. Review will not be cut off absent persuasive reason to believe that Congress so intended. No such reason is discernible here. Pp. 5-6.

(b) Congress, when it composed the Westfall Act, legislated against a backdrop of judicial review: courts routinely reviewed the local U.S. Attorneys scope-of-employment certification under the Acts statutory predecessor. The plain purpose of the Westfall Act was to override Westfall v. Erwin, 484 U.S. 292, which had added a "discretionary function" requirement, discrete from the scope-of-employment test, as a criterion for a federal officers personal immunity. Although Congress thus wanted the employees personal immunity to turn solely on the critical scope-of-employment inquiry, nothing tied to the Acts purpose shows an intent to commit that inquiry to the unreviewable judgment of the Attorney General or her delegate. Pp. 6-8.

(c) Construction of the Westfall Act as Lamagno urges - to deny to federal courts authority to review the Attorney Generals scope-of-employment certification - would oblige this Court to attribute to Congress two highly anomalous commands. First, the Court would have to accept that, whenever the case falls within an exception to the FTCA, Congress has authorized the Attorney General to sit as an unreviewable judge in her own cause - able to block petitioners way to a tort action in court, at no cost to the federal treasury, while avoiding litigation in which the United States has no incentive to engage