Justice Ginsburg
delivered the opinion of the Court, except as to Part IV.
When a federal employee is sued for a wrongful or negli-. gent act, the Federal Employees Liability Reform and Tort [420]*420Compensation Act of 1988 (commonly known as the Westfall Act) empowers the Attorney General to certify that the employee “was acting within the scope of his office or employment at the time of the incident out of which the claim arose . . . 28 U. S. C. §2679(d)(1). Upon certification, the employee is dismissed from the action and the United States is substituted as defendant. The case then falls under the governance of the Federal Tort Claims Act (FTCA), ch. 753, 60 Stat. 812,842. Generally, such cases unfold much as cases do against other employers who concede respondeat superior liability. If, however, an exception to the FTCA shields the United States from suit, the plaintiff may be left without a tort action against any party.
This case is illustrative. The Attorney General certified that an allegedly negligent employee “was acting within the scope of his . . . employment” at the time of the episode in suit. Once brought into the case as a defendant, however, the United States asserted immunity, because the incident giving rise to the claim occurred abroad and the FTCA excepts “[a]ny claim arising in a foreign country.” 28 U. S. C. §2680(k). Endeavoring to redeem their lawsuit, plaintiffs (petitioners here) sought court review of the Attorney General’s scope-of-employment certification, for if the employee was acting outside the scope of his employment, the plaintiffs’ tort action could proceed against him. The lower courts held the certification unreviewable. We reverse that determination and hold that the scope-of-employment certification is reviewable in court.
J — I
Shortly before midnight on January 18, 1991, m Barranquilla, Colombia, a car driven by respondent Dirk A. La-magno, a special agent of the United States Drug Enforcement Administration (DEA), collided with petitioners’ car. Petitioners, who are citizens of Colombia, allege that La-[421]*421magno was intoxicated and that his passenger, an unidentified woman, was not a federal employee.
Informed that diplomatic immunity shielded Lamagno from suit in Colombia, petitioners filed a diversity action against him in the United States District Court for the Eastern District of Virginia, the district where Lamagno resided. Alleging that Lamagno’s negligent driving caused the accident, petitioners sought compensation for physical injuries and property damage.1 In response, the local United States Attorney, acting pursuant to the Westfall Act, certified on behalf of the Attorney General that Lamagno was acting within the scope of his employment at the time of the accident. The certification, as is customary, stated no reasons for the U. S. Attorney’s scope-of-employment determination.2
In the Westfall Act, Congress instructed:
“Upon certification by the Attorney General that the defendant employee was acting within the scope of his office or employment at the time of the incident out of which the claim arose, any civil action or proceeding [422]*422commenced upon such claim in a United States district court shall be deemed an action against the United States under the provisions of this title and all references thereto, and the United States shall be substituted as the party defendant.” § 2679(d)(1).
Thus, absent judicial review and court rejection of the certification, Lamagno would be released from the litigation; furthermore, he could not again be pursued in any damages action arising from the “same subject matter.” § 2679(b)(1). Replacing Lamagno, the United States would become sole defendant.
Ordinarily, scope-of-employment certifications occasion no contest. While the certification relieves the employee of responsibility, plaintiffs will confront instead a financially reliable defendant. But in this case, substitution of the United States would cause the demise of the action: Petitioners’ claims “ar[ose] in a foreign country,” FTCA, 28 U. S. C. §2680(k), and thus fell within an exception to the FTCA’s waiver of the United States’ sovereign immunity. See § 2679(d)(4) (upon certification, the action “shall proceed in the same manner as any action against the United States ... and shall be subject to the limitations and exceptions applicable to those actions”). Nor would the immunity of the United States allow petitioners to bring Lamagno back into the action. See United States v. Smith, 499 U. S. 160 (1991).
To keep their action against Lamagno alive, and to avoid the fatal consequences of unrecallable substitution of the United States as the party defendant, petitioners asked the District Court to review the certification. Petitioners maintained that Lamagno was acting outside the scope of his employment at the time of the accident; certification to the contrary, they argued, was groundless and untrustworthy. Following Circuit precedent, Johnson v. Carter, 983 F. 2d 1316 (CA4) (en banc), cert. denied, 510 U. S. 812 (1993), the District Court held the certification unreviewable, substituted the United States for Lamagno, and dismissed peti[423]*423tioners’ suit. App. 7-9. In an unadorned order, the Fourth Circuit affirmed. 23 F. 3d 402 (1994).
The Circuits divide sharply on this issue. Parting from the Fourth Circuit, most of the Courts of Appeals have held certification by the Attorney General or her delegate amenable to court review.3 We granted certiorari to resolve the conflict, 513 U. S. 998 (1994),4 and we now reverse the Fourth Circuit’s judgment.
II
A
We encounter in this ease the familiar questions: where is the line to be drawn; and who decides. Congress has firmly answered the first question. “Scope of employment” sets the line. See § 2679(b)(1); United States v. Smith, 499 U. S. 160 (1991). If Lamagno is inside that line, he is not subject to petitioners’ suit; if he is outside the line, he is personally answerable. The sole question, then, is who decides on which side of the line the case falls: the local United [424]*424States Attorney, unreviewably or, when that official’s decision is contested, the court. Congress did not address this precise issue unambiguously, if at all. As the division in the lower courts and in this Court shows, the Westfall Act is, on the “who decides” question we confront, open to divergent interpretation.
Two considerations weigh heavily in our analysis, and we state them at the outset. 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 official’s determination of a fact or circumstance — for example, “scope of employment” — is dispositive of a court controversy, federal courts generally do not hold the determination unreviewable. Instead, federal judges traditionally proceed from the “strong presumption that Congress intends judicial review.” Bowen v. Michigan Academy of Family Physicians, 476 U. S. 667, 670 (1986); see id., at 670-673; Abbott Laboratories v. Gardner, 387 U. S. 136, 140 (1967). Chief Justice Marshall long ago captured the essential idea:
“It would excite some surprise if, in a government of laws and of principle, furnished with a department whose appropriate duty it is to decide questions of right, not only between individuals, but between the government and individuals; a ministerial officer might, at his discretion, issue this powerful process ... leaving to [the claimant] no remedy, no appeal to the laws of his country, if he should believe the claim to be unjust. But this anomaly does not exist; this imputation cannot be cast on the legislature of the United States.” United States v. Nourse, 9 Pet. 8, 28-29 (1835).
Accordingly, we have stated time and again that judicial review of executive action “will not be cut off unless there is persuasive reason to believe that such was the purpose of Congress.” Abbott Laboratories, 387 U. S., at 140 (citing [425]*425cases). No persuasive reason for restricting access to judicial review is discernible from the statutory fog we confront here.
B
Congress, when it composed the Westfall Act, legislated against a backdrop of judicial review. Courts routinely reviewed the local United States Attorney’s scope-of-employment certification under the Westfall Act’s statutory predecessor, the Federal Drivers Act, Pub. L. 87-258, § 1, 75 Stat. 539 (previously codified as 28 U. S. C. § 2679(d) (1982 ed.)). Similar to the Westfall Act but narrower in scope, the Drivers Act made the FTCA the exclusive remedy for motor vehicle accidents involving federal employees acting within the scope of their employment. 75 Stat. 539 (previously codified at 28 U. S. C. § 2679(b) (1982 ed.)). The Drivers Act, like the Westfall Act, had a certification scheme, though it applied only to cases brought in state court. Once the Attorney General or his delegate certified that the defendant driver was acting within the scope of employment, the case was removed to federal court and the United States was substituted as defendant. But the removal and substitution were subject to the federal court’s control; a court determination that the driver was acting outside the scope of his employment would restore the case to its original status. See, e. g., McGowan v. Williams, 623 F. 2d 1239, 1242 (CA7 1980); Seiden v. United States, 537 F. 2d 867, 870 (CA6 1976); Levin v. Taylor, 464 F. 2d 770, 771 (CADC 1972).
When Congress wrote the Westfall Act, which covers federal employees generally and not just federal drivers, the legislators had one purpose firmly in mind. That purpose surely was not to make the Attorney General’s delegate the final arbiter of “scope-of-employment” contests. Instead, Congress sought to override Westfall v. Erwin, 484 U. S. 292 (1988). In Westfall, we held that, to gain immunity from suit for a common-law tort, a federal employee would have [426]*426to show (1) that he was acting within the scope of his employment, and (2) that he was performing a discretionary function. Id., at 299. Congress reacted quickly to delete the “discretionary function” requirement, finding it an unwarranted judicial imposition, one that had “created an immediate crisis involving the prospect of personal liability and the threat of protracted personal tort litigation for the entire Federal workforce.” § 2(a)(5), 102 Stat. 4563.
The Westfall Act trained on this objective: to “return Federal employees to the status they held prior to the Westfall decision.” H. R. Rep. No. 100-700, p. 4 (1988). Congress was notably concerned with the significance of the scope-of-employment inquiry — that is, it wanted the employee’s personal immunity to turn on that question alone. See §2(b), 102 Stat. 4564 (purpose of Westfall Act is to “protect Federal employees from personal liability for common law torts committed within the scope of their employment”). But nothing tied to the purpose of the legislation shows that Congress meant the Westfall Act to commit the critical “scope-of-employment” inquiry to the unreviewable judgment of the Attorney General or her delegate, and thus to alter fundamentally the answer to the “who decides” question.
C
Construction of the Westfall Act as Lamagno urges — to deny to federal courts authority to review the Attorney General’s scope-of-employment certification — would oblige us to attribute to Congress two highly anomalous commands. Not only would we have to accept that Congress, by its silence, authorized the Attorney General’s delegate to make determinations of the kind at issue without any judicial check. At least equally perplexing, the proposed reading would cast Article III judges in the role of petty functionaries, persons required to enter as a court judgment an executive officer’s decision, but stripped of capacity to evaluate independently whether the executive’s decision is correct.
[427]*427r — 1
In the typical case, by certifying that an employee was acting within the scope of his employment, the Attorney General enables the tort plaintiff to maintain a claim for relief under the FTCA, a claim against the financially reliable United States. In such a case, the United States, by certifying, is acting against its financial interest, exposing itself to liability as would any other employer at common law who admits that an employee acted within the scope of his employment. See Restatement (Second) of Agency §219 (1958).
.The situation alters radically, however, in the unusual case — like the one before us — that involves an exception to the FTCA.5 When the United States retains immunity from suit, certification disarms plaintiffs. They may not proceed against the United States, nor may they pursue the employee shielded by the certificátion. Smith, 499 U. S., at 166-167. In such a case, the certification surely does not qualify as a declaration against the Government’s interest: it does not expose the United States to liability, and it shields a federal employee from liability.
But that is not all. The impetus to certify becomes overwhelming in a case like this one, as the Attorney General, in siding with petitioners, no doubt comprehends. If the local [428]*428United States Attorney, to whom the Attorney General has delegated responsibility, refuses certification, the employee can make a federal case of the matter by alleging a wrongful failure to certify. See § 2679(d)(3). The federal employee’s claim is one the United States Attorney has no incentive to oppose for the very reason the dissent suggests, see post, at 448-449: Win or lose, the United States retains its immunity; hence, were the United States to litigate “scope of employment” against its own employee — thereby consuming the local United States Attorney’s precious litigation resources— it would be litigating solely for the benefit of the plaintiff. Inevitably, the United States Attorney will feel a strong tug to certify, even when the merits are cloudy, and thereby “do a favor,” post, at 448, both for the employee and for the United States as well, at a cost borne solely, and perhaps quite unfairly, by the plaintiff.
The argument for unreviewability in such an instance runs up against a mainstay of our system of government. Madison spoke precisely to the point:
“No man is allowed to be a judge in his own cause, because his interest would certainly bias his judgment, and, not improbably, corrupt his integrity. With equal, nay with greater reason, a body of men are unfit to be both judges and parties at the same time . . . .” The Federalist No. 10, p. 79 (C. Rossiter ed. 1961).
See In re Murchison, 349 U. S. 133, 136 (1956) (“[0]ur system of law has always endeavored to prevent even the probability of unfairness. To this end no man can be a judge in his own case and no man is permitted to try cases where he has an interest in the outcome.”); Spencer v. Lapsley, 20 How. 264, 266 (1858) (recognizing statute accords with this maxim); see also Publius Syrus, Moral Sayings 51 (D. Lyman transí. 1856) (“No one should be judge in his own cause.”); B. Pascal, Thoughts, Letters and Opuscules 182 (0. Wight transí. 1859) (“It is not permitted to the most equitable of men to be a [429]*429judge in his own cause.”); 1 W. Blackstone, Commentaries *91 (“[I]t is unreasonable that any man should determine his own quarrel.”).
In sum, under Lamagno’s reading of the congressional product at issue, whenever the case falls within an exception to the FTCA, the Attorney General sits as an unreviewable “judge in her own cause”; she can 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, and incidentally enhancing the morale — or at least sparing the purse — of federal employees. The United States, as we have noted, disavows this extraordinary, conspicuously self-serving interpretation. See supra, at 424, and n. 4. Recognizing that a United States Attorney, in cases of this order, is hardly positioned to act impartially, the Attorney General reads the law to allow judicial review.
If Congress made the Attorney General’s delegate sole judge, despite the apparent conflict of interest, then Congress correspondingly assigned to the federal court only rubber-stamp work. Upon certification in a case such as this one, the United States would automatically become the defendant and, just as automatically, the case would be dismissed. The key question presented — scope of employment — however contestable in fact, would receive no judicial audience. The court could do no more, and no less, than convert the executive’s scarcely disinterested decision into a court judgment. This strange course becomes all the more surreal when one adds to the scene the absence of an obligation on the part of the Attorney General’s delegate to conduct a fair proceeding, indeed, any proceeding. She need not give the plaintiff an opportunity to speak to the “scope” question, or even notice that she is considering the question. Nor need she give any explanation for her action.
[430]*430Congress may be free to establish a compensation scheme that operates without court participation. Cf. 21 U. S. C. §904 (authorizing executive settlement of tort claims that “arise in a foreign country in connection with the operations of the [DEA] abroad”). But that is a matter quite different from instructing a court automatically to enter a judgment pursuant to a decision the court has no authority to evaluate. Cf. United States v, Klein, 13 Wall. 128, 146 (1872) (Congress may not “prescribe rules of decision to the Judicial Department of the government in cases pending before it”). We resist ascribing to Congress an intention to place courts in this untenable position.6
Ill
We return now, in more detail, to the statutory language to determine whether it overcomes the presumption favoring judicial review, the tradition of court review of scope certifications, and the anomalies attending foreclosure of review.
The certification, removal, and substitution provisions of the Westfall Act, 28 U. S. C. §§2679(d)(l)-(3),7 work together [431]*431to assure that, when scope of employment is in controversy, that matter, key to the application of the FTCA, may be resolved in federal court. To that end, the Act specifically allows employees whose certification requests have been denied by the Attorney General, to contest the denial in court. § 2679(d)(3). If the action was initiated by the tort plaintiff in state court, the Attorney General, on the defendant-employee’s petition, is to enter the case and may remove it to the federal court so that the scope determination can be made in the federal forum. Ibid.
When the Attorney General has granted certification, if the case is already in federal court (as is this case, because of the parties’ diverse citizenship), the United States will be substituted as the party defendant. § 2679(d)(1). If the case was initiated by the tort plaintiff in state court, [432]*432the Attorney General is to remove it to the federal court, where, as in a case that originated in the federal forum, the United States will be substituted as the party defendant. § 2679(d)(2).
The statute next instructs that the “certification of the Attorney General shall conclusively establish scope of office or employment for purposes of removal.” Ibid, (emphasis added). The meaning of that instruction, in the view of petitioners and the Attorney General, is just what the emphasized words import. Congress spoke in discrete sentences in § 2679(d)(2) first of removal, then of substitution. Next, Congress made the Attorney General’s certificate conclusive solely for purposes of removal, and notably not for purposes of substitution. It follows, petitioners and the Attorney General conclude, that the scope-of-employment judgment determinative of substitution can and properly should be checked by the court, i. e., the Attorney General’s scarcely disinterested certification on that matter is by statute made the first, but not the final word.
Lamagno’s construction does not draw on the “certification . . . shall [be conclusive] ... for purposes of removal” language of § 2679(d)(2).8 Instead, Lamagno emphasizes the word “shall” in the statement: “Upon certification by the Attorney General . . . any civil action or proceeding . . . shall be deemed an action against the United States ..., and the United States shall be substituted as the party defendant.” § 2679(d)(1) (emphasis added). Any doubt as to the commanding force of the word “shall,”9 Lamagno urges, is dis[433]*433pelled by this further feature: the Westfall Act’s predecessor, the Federal Drivers Act, provided for court review of “scope-of-employment” certifications at the tort plaintiff’s behest. Not only does the Westfall Act fail to provide for certification challenges by tort plaintiffs,10 Lamagno underscores, but the Act prominently provides for court review of [434]*434refusals to certify at the behest of defending employees. See § 2679(d)(3). Congress, in Lamagno’s view, thus plainly intended the one-sided review, i. e., a court check at the call of the defending employee, but no check at the tort plaintiff’s call.
We recognize that both sides have tendered plausible constructions of a text most interpreters have found far from clear. See, e. g., McHugh v. University of Vermont, 966 F. 2d 67, 72 (CA2 1992) (“[T]he text of the Westfall Act, viewed as a whole, is ambiguous.”); Arbour v. Jenkins, 903 F. 2d 416, 421 (CA6 1990) (“[T]he scope certification provisions of the Westfall Act as a whole . . . [are] ambiguous regarding the reviewability of the Attorney General’s scope certification.”). Indeed, the United States initially took the position that the local United States Attorney’s scope-of-employment certifications are conclusive and unreviewable but, on further consideration, changed its position. See Brief for United States 14, n. 4. Because the statute is reasonably susceptible to divergent interpretation, we adopt the reading that accords with traditional understandings and basic principles: that executive determinations generally are subject to judicial review and that mechanical judgments are not the kind federal courts are set up to render. Under our reading, the Attorney General’s certification that a federal employee was acting within the scope of his employment — a certification the executive official, in cases of the kind at issue, has a compelling interest to grant — does not conclusively establish as correct the substitution of the United States as defendant in place of the employee.
> HH
Treating the Attorney General’s certification as conclusive for purposes of removal but not for purposes of substitution, amicus ultimately argues, “raise[s] a potentially serious Article III problem.” Brief for Michael K. Kellogg as Amicus Curiae 29. If the certification is rejected, because the fed[435]*435eral court concludes that the employee acted outside the scope of his employment, and if the tort plaintiff and the employee resubstituted as defendant are not of diverse citizenship, amicus urges, then the federal court will be left with a case without a federal question to support the court’s subject-matter jurisdiction. This last-pressed argument by amicus largely drives the dissent. See post, at 440-443.
This case itself, we note, presents not even the specter of an Article III problem. The case was initially instituted in federal court; it was not removed from a state court. The parties’ diverse citizenship gave petitioners an entirely secure basis for filing in federal court.
In any event, we do not think the Article III problem ami-cus describes is a grave one. There may no longer be a federal question once the federal employee is resubstituted as defendant, but in the category of cases amicus hypothesizes, there was a nonfrivolous federal question, certified by the local United States Attorney, when the case was removed to federal court. At that time, the United States was the defendant, and the action was thus under the FTCA. Whether the employee was acting within the scope of his federal employment is a significant federal question — and the Westfall Act was designed to assure that this question could be aired in a federal forum. See supra, at 430-432. Because a case under the Westfall Act thus “raises [a] questio[n] of substantive federal law at the very outset,” it “clearly ‘arises under’ federal law, as that term is used in Art. III.” Verlinden B. V. v. Central Bank of Nigeria, 461 U. S. 480, 493 (1983).
In adjudicating the scope-of-federal-employment question “at the very outset,” the court inevitably will confront facts relevant to the alleged misconduct, matters that bear on the state tort claims against the employee. Cf. Mine Workers v. Gibbs, 383 U. S. 715, 725 (1966) (approving exercise of pendent jurisdiction when federal and state claims have “a common nucleus of operative fact” and would “ordinarily be [436]*436expected to [be tried] all in one judicial proceeding”). “[C]on-siderations of judicial economy, convenience and fairness to litigants,” id., at 726, make it reasonable and proper for the federal forum to proceed beyond the federal question to final judgment once it has invested time and resources on the initial scope-of-employment contest.11
If, in preserving judicial review of scope-of-employment certifications, Congress “approach[ed] the limit” of federal-court jurisdiction, see post, at 441 — and we do not believe it did — we find the exercise of federal-court authority involved here less ominous than the consequences of declaring certifications of the kind at issue uncontestable: The local United States Attorney, whose conflict of interest is apparent, would be authorized to make final and binding decisions insulating both the United States and federal employees like Lamagno from liability while depriving plaintiffs of potentially meritorious tort claims. The Attorney General, having weighed the competing considerations, does not read the statute to confer on her such extraordinary authority. Nor should we assume that Congress meant federal courts to accept cases only to stamp them “Dismissed” on an interested executive official’s unchallengeable representation. The statute is fairly construed to allow petitioners to present to the Dis[437]*437trict Court their objections to the Attorney General’s scope-of-employment certification, and we hold that construction the more persuasive one.
* * *
For the reasons stated, the judgment of the United States Court of Appeals for the Fourth Circuit is reversed, and the case is remanded for proceedings consistent with this opinion.
It is so ordered.