Viewed broadly, this appeal concerns a bitter dispute about the parties’ rights in and to Facebook, a spectacularly successful creature of the information age. Viewed more narrowly, however, it presents a jurisdictional enigma that requires us to decide whether an amended complaint that switches the basis of the district court’s subject matter jurisdiction from the existence of diversity of citizenship, 28 U.S.C. § 1332(a)(1), to the existence of a federal question, id. § 1331, should be given effect when filed as of right before any jurisdictional challenge has been mounted. This is a question of first impression at the federal appellate level — and one that sets two establishеd legal principles on a collision course.
For the reasons that follow, we hold that the jurisdictional claim in the amended complaint warrants full consideration and constitutes a viable hook on which federal jurisdiction can be hung. Because this holding is at odds with the conclusions reached by the court below, we reverse the order of dismissal and remand for further proceedings consistent with this opinion.
I. BACKGROUND
The relevant facts can be succinctly summarized. We wrest them from the *86 allegations of the original and amended complaints (cautioning, however, that many of the substantive details appear to be hotly disputed).
The seeds of the global controversy wеre sown in a Harvard College dormitory room. Tyler Winklevoss, Cameron Wink-levoss, and Divya Narendra (the Founders), then Harvard undergraduates, hatched the idea of creating a social networking website for college students. Lacking the programming expertise necessary to bring this idea to fruition, the Founders asked defendant Mark Zucker-berg to help them complete the proposed website’s source code and aid in the development of their embryonic website. The request, which was made and accepted in November of 2003, yielded an horrific harvest.
According to the Founders, Zuckerberg not only failed to carry out the assignment but also stole their idea, businеss plan, and rudimentary (unfinished) source code in order to launch a competing social networking website. Zuckerberg acted in secret. By the time that the Founders learned of his perfidy, completed the source code through other means, and inaugurated their own social networking website (originally called harvardconnection.com and later renamed connec-tU.com), Zuckerberg’s venture (originally called thefacebook.com and later abbreviated facebook.com) had gotten an unbeatable head start in user traffic. 1
Harvard’s traditional school color .is crimson but the Founders saw red. On September 2, 2004, ConnectU LLC, a Delaware limited liability company (the LLC) commenced an action in the federal district court premised on diversity of citizenship and the existence of a controversy in the requisite amount, 28 U.S.C. § 1332(a)(1), against Zuckerberg and five other defendants associated with him, namely, Dustin Moskovitz, Eduardo Saverin, Andrew McCollum, Christopher Hughes, and Face-book itself. The complaint linked the three Founders with the LLC and asserted a gallimaufry of state-law claims arising from the alleged misappropriation and unauthorized use of the LLC’s confidential source code and business plan.
On October 28, 2004 — approximately two weeks after registering a copyright for its website’s source code with the United States Copyright Office and before any responsive pleading was filed by the defendants — the LLC served an amended complaint. See Fed.R.CivJP. 15(a). The amended complaint added a corporate affiliate of Facebook as a defendant and introduced two new statements of claim, including a federal-law claim for copyright infringement. At the same time, the amended complaint forsook diversity as the basis for federal subject matter jurisdiction and premised jurisdiction instead on the existence of a federal question. See 28 U.S.C. § 1331. That federal question consisted of the newly asserted copyright infringement claim, see 17 U.S.C. § 501(b), and carried with it supplemental jurisdiction over the armada of state-law claims, see 28 U.S.C. § 1367(a).
Almost one year later, the defendants moved to dismiss for want of subject matter jurisdiction. 2 Fed.R.Civ.P. *87 12(b)(1). They argued that the parties to the original complaint were not wholly diverse and that, therefore, the LLC’s jurisdictional allegation did not hold water.
The defendants’ argument had to be re-calibrated in light of our ensuing decision in
Pramco, LLC v. San Juan Bay Marina, Inc.,
This argument focused on the jurisdictional basis set forth in the original complaint because, in the defendants’ view, the amended complaint was beside the point. For this proposition, they cited the time-of-filing rule reiterated in
Grupo Dataflux v. Atlas Global Group L.P.,
The LLC countered that the existence vel non of diversity had become a non-issue because the amended complaint, which premised jurisdiction on the existence of a federal question, had become the operative pleading. In the alternative, the LLC maintained that the parties to the original complaint were wholly diverse at the time of the commencement of the action. In support of this last proposition, the LLC suggested that Narendra’s citizenship should not figure into the diversity calculus because he had not been admitted as a member of the LLC and that, at any rate, Zuckerberg was a citizen of California, not New York.
The district judge referred the dismissal motion to a magistrate judge for a report and recommendation.
See
28 U.S.C. § 636(b)(1); Fed.R.Civ.P. 72(b). After holding a protracted evidentiary hearing, the magistrate judge recommended that the motion to dismiss be granted.
Con-nectU LLC v. Zuckerberg, (ConnectU I),
The LLC objected to the magistrate judge’s report and recommendation. The district judge summarily overruled these objections, adopted the recommended decision, and dismissed the case without prejudice for want of subject matter jurisdiction. 4 This timely appeal ensued. Simultaneous with the filing of the notice of appeal, the LLC’s successor-in-interest *88 commenced a new action in the district court (ConnectU II) asserting matеrially identical claims against the same defendants.
II. ANALYSIS
Although the LLC advances multiple claims of error on appeal, only one of them — its contention that the district court failed to treat the amended complaint as the operative pleading for the purpose of determining subject matter jurisdiction— need concern us. Before addressing the merits of that contention, however, we must deal with the defendants’ plaint that this appeal should be dismissed as moot.
A. Mootness.
The Constitution confines the jurisdiction of the federal courts to actual cases and controversies. U.S. Const, art. Ill, § 2, cl. 1. This prerequisite must be satisfied at each and every stage of the litigation.
See Spencer v. Kemna,
An appeal becomes moot if an intervening event strips the parties of any legally cognizable interest in the outcome.
See Murphy v. Hunt,
Here, the defendants posit that this appeal no longer embodies a live case or controversy because the LLC’s successor-in-interest, ConnectU, Inc., has instituted a new, materially identical action in the district court. In the defendants’ view, this initiative renders the earlier action superfluous and, hence, destroys the utility of this appeal. We do not agree.
We assume for argument’s sake, favorably to the defendants, that ConnectU, Inc. and the LLC are so closely tied that they are for present purposes one firm. But although the virtual firm has chosen to institute a second action asserting materially identical claims, it retains a legally cognizable interest in the outcome of this appeal. We explain briefly.
There is a recognized defense to a claim of mootness in the аppellate context when a party can demonstrate that a lower court’s decision, if allowed to stand, may have collateral consequences adverse to its interests.
See Horizon Bank & Trust Co. v. Massachusetts,
The key is in the timing. The commencement of
ConnectU I
tolled the appli
*89
cable statutes of limitations approximately two-and-one-half years earlier than did the commencement of
ConnectU II.
Thus, a reversal of the dismissal order would mitigate the force of any limitations defenses relied on by the defendants in
ConnectU II.
This is a collateral consequence of the type that suffices to defuse a claim of mootness.
See
13A Charles Alan Wright, Arthur R. Miller & Edward H. Cooper,
Federal Practice and Procedure
§ 3533.3, at 291 (2d ed. 1984) (“Collateral consequences may be found in the prospect that a judgment will affect future litigation or administrative action.”);
cf. Patriot Cinemas, Inc. v. Gen. Cinemas Corp.,
In an effort to coax us away from this result, the defendants chant a familiar mantra: that collateral consequences that are remote or speculative will not inoculate an appeal against a finding of mootness.
See In re Burrell,
We also reject the defendants’ importunings to the effect that a case is rendered moot simply because a plaintiff has decided to pursue two overlapping actions simultaneously. The law is pellucid that an аction is not automatically rendered moot by the mere existence of a similar pending action.
5
See, e.g., Pieczenik v. Dyax Corp.,
The defendants’ final effort to convince us that the appeal is moot hinges on the notion that the decision to file a new action constituted an election of remedies. 6 We are not persuaded.
The election of remedies doctrine is grounded on equitable principles.
See Far W. Fed. Bank v. Office of Thrift Superv’n-Dir.,
That ends this aspect of the matter. Concluding, as we do, that this appeal is not moot, we move to the validity of the dismissal order.
B. Subject Matter Jurisdiction.
The order of dismissal hinges on the existence vel non of subject matter jurisdiction. Our inquiry into subject matter jurisdiction depends, in the first instance, on which pleading — -the original complaint or the amended complaint — controls. At the outset, however, we pause to comment upon an arcane bit of nomenclature.
There is an open question as to whether an amended complaint asserting a cause of action that arose only after the prior complaint was filed should be regarded as a “supplemental” rather than an “amended” complaint. The difference is modest. An amended complaint filed pursuant to Federal Rule of Civil Procedure 15(a) typically relates to matters that have taken place prior to the date of the pleading that is being amended. See 6 Charles Alan Wright, Arthur R. Miller & Mary Kay Kane, supra § 1473 (Supp.2007). A supplemental complaint typically allows the pleader to “set[ ] forth transactions or occurrences or events which have happened since the date of the pleading sought to be supplemented.” Fed.R.Civ.P. 15(d). An amended complaint sometimes can be filed “as a matter of course,” Fed.R.Civ.P. 15(a); a supplemental complaint cannot.
Here, however, the question of which label applies is more theoretical than real. The parties and the district court consistently have treated the neoteric pleading as an amended complaint. The defendants did not move to strike it, nor have they presented any developed argumentation either below or on appeal to the effect that the pleading should be regarded as a supplemental complaint. Thus, any issue regarding the possible status of the pleading as a supplemental complaint is waived.
7
See United States v. Zannino,
This brings the preserved claim of error front and center. The LLC argues that the district court erroneously regarded the original complaint as controlling for the purpose of gauging subject matter jurisdiction. In its view, the amended complaint, filed as of right under Federal Rule of Civil Procedure 15(a), superseded the original complaint and rendered it functus officio.
The defendants demur. They argue that an action originally filed under diversity jurisdiction — like this one — must, in line with longstanding Supreme Court precedent, live or die from a jurisdictional standpoint as of the time of filing regardless of subsequent changes in either the *91 facts or the underlying jurisdictional allegations.
We begin our formulation of an answer to this conundrum with a recognition that the parties’ competing arguments combine to pose a pure question of law and, therefore, engender de novo review.
See Young v. Lepone,
For aught that appears, this is precisеly what happened here. The LLC amended its complaint before the defendants filed a responsive pleading and, thus, the amendment was effective as a matter of right pursuant to Rule 15(a). Consequently, under ordinary rules of pleading and practice, the amended complaint would have replaced the original complaint lock, stock, and barrel.
See id.; InterGen,
This result draws substantial support from a recent Supreme Court decision. In
Rockwell International Corp. v. United States,
— U.S.-,
The matter is complicated, however, by the existence of a different line of authority, headed by Grupo Dataflux. In the district court’s view, Grupo Dataflux reaffirmed the time-of-filing rule and required it to turn a blind eye to any attempt to change the jurisdictional basis of the action. As we explain below, we believe that the district court misconceived the reach of the time-of-filing rule.
Historically, diversity jurisdiction requires complete diversity of citizenship as between all plaintiffs and all defendants.
See Strawbridge v. Curtiss,
*92
Notwithstanding the impressive pedigree of the time-of-filing rule, it is inapposite here. The letter and spirit of the rule apply most obviously in diversity cases, where the rule originated,
see Mollan,
More importantly, no court has ever read the time-of-filing rule to bar a plaintiff from switching jurisdictional horses before any jurisdictional issue has been raised, abandoning a claimed entitlement to diversity jurisdiction, and substituting a claimed entitlement to federal question jurisdiction. Certainly, the decision in
Gru-po Dataflux
does not adumbrate such a result. While the Court there relied upon the time-of-filing rule to thwart an effort to manufacture diversity jurisdiction during the pendency of an action,
A lightning tour of
Grupo Dataflux
illustrates why we find that opinion unhelpful to the defendants’ cause. There, a Texas limited partnership invoked diversity jurisdiction and filed a breach of contract action in federal district court against a Mexican corporation.
Id.
at 568,
On appeal, the plaintiff argued that the two Mexican nationals had been dropped from the partnership prior to trial and, thus, should be disregarded for purposes of a diversity analysis. The court of appeals agreed.
Id.
at 569-70,
As this account makes manifest, the
Grupo Dataflux
Court explicitly restricted the time-of-filing rule to diversity cases. Nothing in the opinion intimates that the Court meant to extend the rule wholesale beyond the frontiers of the diversity context. Doing so would have represented a major innovation, and a lower federal court should be slow to assume that the Supreme Court has taken a significant doctrinal step by indirection or innuendo.
Cf. Whitman v. Am. Trucking Ass’ns, Inc.,
The case at hand is at a considerable remove from Grupo Dataflux. Here, unlike the plaintiff in that case, the LLC claims an entitlement to federal question jurisdiction. That claim does not depend on a manipulation of its business membership in order to fabricate complete diversity. Rather, the LLC amended its complaint in response to its copyright registration and altered the jurisdictional foundation of its action. At that point— that is, once the amended complaint superseded the original complaint — this case became a federal question case, not a diversity case. Nothing in Grupo Dataflux bars a legitimate shifting of the jurisdictional underpinnings of an action; and nothing in Grupo Dataflux demands the extension of the time-of-filing rule to a run-of-the-mill federal question case.
We add, moreover, that we can see no policy-based reason for elongating the reach of the time-of-filing rule and applying it to a case in which a plaintiff forsakes a claimed entitlement to diversity jurisdiction in favor of a claimed entitlement to federal question jurisdiction. After all, the plaintiff is both the author and the master of its complaint.
See Holmes Group, Inc. v. Vornado Air Circ’n Sys., Inc.,
It bears emphasis that the time-of-filing rule is a judge-made construct: it does not owe its existence to any interpretation of constitutional or statutory text that demands our allegiance.
See Grupo Dataf-lux,
These policy concerns, indigenous to diversity cases, are largely absent in federal question cases. Diversity depends in material part on citizenship, and citizenship is a matter of choice that easily can be influenced, in a mobile society, by the simple expedient of moving from place to place as a case prоgresses.
See, e.g., Hawes v. Club Ecuestre El Comandante,
It follows that whereas a uniform, easily administered test is a practical necessity in diversity cases, no comparable need exists in federal question cases.
See Boelens,
The defendants have a fallback position. They asseverate that, even if the time-of-filing rule does not pertain, an amended complaint cannot relate back to an earlier pleading over which the court had no jurisdiction. This asseveration rests on the assumption that the district court did not have diversity jurisdiction over the action at the time of filing. Even if that were so — a matter on which we take no view — the argument mixes plums with pomegranates. Rule 15(c)’s language about the relation back of amendments has no bearing here.
The purpose of Rule 15(c) is to allow a plaintiff to avoid the preclusive effect of a statute of limitations so long as certain conditions are satisfied.
See, e.g., Leonard v. Parry,
In all events, the LLC’s amended complaint did not “cure” a jurisdictional defect by engaging the gears of Rule 15(c)’s relation back mechanism. 9 Instead, it replacеd the original complaint in its entirety — and it did so at a point when the district court’s jurisdiction had not yet been questioned.
The defendants attempt to analogize this case to our decisions in
USM Corp.
and
Cicchetti.
That proffered analogy is flawed. In
USM Corp.,
we dismissed an appeal from a stay order for lack of appellate jurisdiction because the underlying claim was predominantly equitable in nature; therefore, the claim was not arbitra-ble and the stay could not be appealed.
The case before us is a horse of a markedly different hue. In contrast to the plaintiffs in USM Corp. and Cicchetti, the LLC did not resort to the relation back mechanism in order to resurrect jurisdiction that already had been found wanting (indeed, the LLC’s claim of entitlement to federal question jurisdiction, as we see it, does not depend upon the relation back mechanism at all). Rather, the LLC’s amended complaint became the operative pleading by operation of law before any jurisdictional challenge was mounted. For present purposes, the new pleading did no more thаn memorialize the LLC’s decision to rely on federal question jurisdiction in lieu of diversity jurisdiction.
The defendants have a final shot in their sling. They note, uncontroversially, that federal courts do not possess and should not presume to exercise hypothetical jurisdiction.
See Steel Co. v. Citizens for a Better Env’t,
As an initial matter, the case law indicates that a court sometimes may constitutionally exercise jurisdiction over a case even though it does not secure solid jurisdictional footing until
after
the case has been brought.
See, e.g., Caterpillar, Inc. v. Lewis,
Perhaps more important, by looking to the amended rather than the original complaint, a court does not “ ‘assume[ ]’ jurisdiction for the purpose of deciding the merits.”
Steel Co.,
The golconda of cases cited by the defendants are not to the contrary. In each of them, the plaintiff asked the district court to grant them leave to amend their complaint after a jurisdictional challеnge had been lodged (or, in some instances, adjudicated).
See, e.g., Boelens,
These are salient differences. A motion for leave to file an amended complaint necessarily implicates a district court’s authority to grant or deny the motion.
See Falise v. Am. Tobacco Co.,
But where, as here, a plaintiff amends its complaint as of right, the Civil Rules operate mechanically, and the judge’s authority over the case is not brought to bear. In that event, the absence of federal subject matter jurisdiction in the original complaint will pose no obstacle to the consideration of an amended complaint.
See Integrated Tech.,
To sum up, we hold that the instant appeal is not moot; that the amended complaint, filed as of right, superseded and replaced the original complaint; that the action was at that point transformed into a federal question case (at least in the circumstances at hand); that the time-of-filing rule does not apply to such a case; and that the district court erred in looking to the original complaint and applying the time-of-filing rule. The district court therefore mistakenly granted the defendants’ motion to dismiss; the court had, and should have exercised, federal question jurisdiction over the action.
III. CONCLUSION
We need go no further. Although the defendants have advanced other arguments, those arguments are either unavailing, or inadequately developed, or both. We reject them out of hand and, for the reasons elucidated above, we reverse the order of dismissal. We remand the matter to the district court for further proceedings consistent with this opinion (inсluding reinstatement of the previously dismissed state-law counts). The district court should consider, among other things, whether Connect'd I and ConnectU II should be consolidated pursuant to Fed. R.Civ.P. 42(a).
Reversed and Remanded.
Notes
. As of March 2008, Facebook boasted over 60,000,000 users and had become the fifth most trafficked website in the United States.
. Although belated, the motion was not untimely. An absence of subject matter jurisdiction can be raised at any time.
See Am. Fiber & Fin., Inc. v. Tyco Healthcare Group, LP,
. The reasoning of the magistrate judge is intricate and depends in large measure on a problematic interpretation of Delaware statutory law. Because we find the jurisdictional allegations of the amended complaint controlling, see text infra, no useful purpose would be served by an analysis of that reasoning.
. To simplify our discussion, we do not hereafter distinguish between the magistrate judge and the district judge but, rather, take an institutional view and refer only to “the district court.”
. While we have cautioned that a party should not file duplicative lawsuits in the same court,
Sutcliffe Storage & Ware. Co. v. United States,
. The defendants’ argument that the appeal is mоot because the LLC failed to register to do business in Massachusetts prior to filing suit is not a mootness argument at all. At any rate, our decision that the district court should have looked to the amended complaint for the purpose of determining subject matter jurisdiction, see text infra, makes the purported failure to register at an earlier date irrelevant.
. In any case, given that the amended complaint was filed as of right, the characterization of the pleading is of little moment; any error in this instance would appear to be harmless. See, e.g., 6A Wright et ah, supra § 1504, at 184-86. Furthermore, even though copyright law requires copyright registration as a prerequisite to instituting a copyright infringement suit in federal cоurt, 17 U.S.C. § 411(a), "registration is not a condition for copyright protection,” id. § 408(a). Because the alleged violation of the instant copyright began prior to the filing of the original complaint, the conclusion of likely harmlessness is strengthened.
. While there
are
outliers,
see, e.g., Rosa v. Resolution Trust Corp.,
. In fairness to the defendants, the LLC did proffer a “relation back’’ argument — but that argument was both ill-conceived and unnecessary to our conception of the way in which this appeal should be resolved.
