 United States Court of Appeals
          FOR THE DISTRICT OF COLUMBIA CIRCUIT



Argued April 14, 2014                    Decided May 27, 2014

                         No. 12-7135

                     AF HOLDINGS, LLC,
                         APPELLEE

                               v.

                        DOES 1 – 1058,
                         APPELLEES

             COX COMMUNICATIONS, INC., ET AL.,
                     APPELLANTS


         Appeal from the United States District Court
                 for the District of Columbia
                     (No. 1:12-cv-00048)


    Benjamin J. Fox argued the cause for appellants. With
him on the briefs were Deanne E. Maynard, Bart W. Huffman,
Hugh S. Balsam, John D. Seiver, Ronald G. London, Leslie G.
Moylan, and Lisa B. Zycherman. Marc A. Hearron entered an
appearance.

    Corynne McSherry argued the cause for amici curiae
Electronic Frontier Foundation, et al. in support of appellants.
On the brief were Mitchell L. Stoltz, Arthur B. Spitzer,
Catherine Crump, and Paul Alan Levy.
                              2
    Paul A. Duffy argued the cause and filed the brief for
appellee AF Holdings, LLC.

   Before: TATEL, Circuit Judge, and SILBERMAN and
SENTELLE, Senior Circuit Judges.

    Opinion for the Court filed by Circuit Judge TATEL.

     TATEL, Circuit Judge: Generally speaking, our federal
judicial system and the procedural rules that govern it work
well, allowing parties to resolve their disputes with one
another fairly and efficiently. But sometimes individuals seek
to manipulate judicial procedures to serve their own improper
ends. This case calls upon us to evaluate—and put a stop to—
one litigant’s attempt to do just that.

                              I.
     Appellee AF Holdings, a limited liability company
formed in the Caribbean islands of Saint Kitts and Nevis, sued
and then sought discovery regarding more than a thousand
unknown individuals who it claimed had illegally shared a
copyrighted pornographic film. This interlocutory appeal
arises from a district court order granting AF Holdings’s
discovery requests.

     A full understanding of this case requires knowing some
things about the lawyer and “law firm” that initiated it. AF
Holdings is represented by attorney Paul A. Duffy. Until very
recently, Duffy was associated with “Prenda Law,” an
organization that, since representing AF Holdings in the
district court, appears to have disbanded and then
reconstituted itself in a similar form. See Ben Jones, Prenda
Suffers More Fee Award Blows, TorrentFreak (August 9,
2013), http://torrentfreak.com/prenda-suffers-more-fee-award
-blows-130809.
                               3

     Prenda Law, as Judge Otis Wright II put it in a case
similar to this, was a “porno-trolling collective.” Ingenuity 13
LLC v. John Doe, No. 2:12-cv-8333, 2013 U.S. Dist. LEXIS
64564, at *3 (C.D. Cal. May 6, 2013). According to Judge
Wright, Duffy and the other principals of Prenda Law were
“attorneys with shattered law practices” who, “[s]eeking easy
money, . . . formed . . . AF Holdings,” acquired “several
copyrights to pornographic movies,” then initiated massive
“John Doe” copyright infringement lawsuits. Id. at *5–6.
These suits took advantage of judicial discovery procedures in
order to identify persons who might possibly have
downloaded certain pornographic films. Such individuals,
although generally able to use the Internet anonymously, are,
like all Internet users, linked to particular Internet Protocol
(IP) addresses, a series of numbers assigned to each Internet
service subscriber. Internet service providers like Appellants
can use IP addresses to identify these underlying subscribers,
but not necessarily the individuals actually accessing the
Internet through the subscribers’ connections at any given
time. Confronted with these realities, Prenda Law’s general
approach was to identify certain unknown persons whose IP
addresses were used to download pornographic films, sue
them in gigantic multi-defendant suits that minimized filing
fees, discover the identities of the persons to whom these IP
address were assigned by serving subpoenas on the Internet
service providers to which the addresses pertained, then
negotiate settlements with the underlying subscribers—a
“strategy [that] was highly successful because of statutory-
copyright damages, the pornographic subject matter, and the
high cost of litigation.” Id. at *6–7; see also Claire Suddath,
Prenda Law, the Porn Copyright Trolls, Bloomberg
Businessweek (May 30, 2013), http://www.businessweek.com
/articles/2013-05-30/prenda-law-the-porn-copyright-trolls
(recounting Prenda Law’s history and litigation tactics). If an
                              4
identified defendant sought to actually litigate, Prenda Law
would simply dismiss the case. See Ingenuity 13 LLC, 2013
U.S. Dist. LEXIS 64564, at *6–7. As Duffy acknowledged at
oral argument, of the more than one hundred cases that AF
Holdings has initiated, none has proceeded to trial or resulted
in any judgment in its favor other than by default. Oral Arg.
Rec. 30:09–20. Nevertheless, according to one article, Prenda
Law made around $15 million in a little less than three years.
See Kashmir Hill, How Porn Copyright Lawyer John Steel
Has Made a ‘Few Million Dollars’ Pursuing (Sometimes
Innocent) ‘Porn Pirates’, Forbes (Oct. 15, 2012),
http://www.forbes.com/sites/kashmirhill/2012/10/15/how-
porn-copyright-lawyer-john-steele-justifies-his-pursuit-of-
sometimes-innocent-porn-pirates.

     The present lawsuit is a quintessential example of Prenda
Law’s modus operandi. Represented by Prenda Law, AF
Holdings brought suit in the United States District Court for
the District of Columbia against 1,058 unnamed Does who it
alleged had illegally downloaded and shared the pornographic
film Popular Demand using a file-sharing service known as
BitTorrent. As an attachment to its complaint, AF Holdings
listed the 1,058 IP addresses assigned to those subscribers
whose Internet connections had been used to share Popular
Demand, along with the specific date and time at which it,
using what it described as “sophisticated and proprietary peer-
to-peer network forensic software,” had observed each
defendant’s allegedly infringing activity. AF Holdings also
attached the purported assignment agreement through which it
claims to have acquired the copyright to Popular Demand.
Although it has no effect on our resolution of this appeal,
other courts have since concluded that at least one of the
signatures on this document was forged. See Ingenuity 13
LLC, 2013 U.S. Dist. LEXIS 64564, at *8; AF Holdings LLC
v. Navasca, No. C-12-2396, 2013 U.S. Dist. LEXIS 102249,
                              5
at *3–4 (N.D. Cal. July 22, 2013); AF Holdings, LLC v.
Doe(s), No. 12-1445, 2013 U.S. Dist. LEXIS 187458, at *10–
12 (D. Minn. Nov. 6, 2013), vacated by AF Holdings, LLC v.
Doe, No. 12-1445, 2014 U.S. Dist. LEXIS 43318 (D. Minn.
Mar. 27, 2014); see also Lightspeed Media Corp. v. Smith,
No. 12-889, 2013 U.S. Dist. LEXIS 168615, at *16 (S.D. Ill.
Nov. 27, 2013) (“The[ principals of Prenda] have shown a
relentless willingness to lie to the Court on paper and in
person, despite being on notice that they were facing
sanctions in this Court, being sanctioned by other courts, and
being referred to state and federal bars, the United States
Attorney in at least two districts, one state Attorney General,
and the Internal Revenue Service.” (internal citations
omitted)).

    Moving for leave to take immediate discovery, AF
Holdings then sought to serve subpoenas on the five Internet
service providers linked to the 1,058 IP addresses it had
identified: Cox Communications, Verizon, Comcast, AT&T,
and Bright House Networks. The district court granted the
motion, authorizing the issuance of subpoenas compelling
these providers to turn over the names, addresses, telephone
numbers, and email addresses of the underlying subscribers.

     The providers refused to comply. Invoking Federal Rule
of Civil Procedure 45(d)(3)(A), which provides that a district
court “must quash or modify a subpoena that . . . subjects a
person to undue burden,” they asserted that the administrative
expense involved was necessarily an “undue burden” because
AF Holdings had failed to establish that the court would have
personal jurisdiction over the defendants or that venue would
lie in this district. Supporting these contentions, Verizon
asserted that its preliminary investigation revealed that only
20 of the 188 Verizon subscribers whose information AF
Holdings sought resided in the District of Columbia. Comcast
                               6
reported that only one of the 400 Comcast subscribers AF
Holdings identified appeared to live in the District. And Cox,
AT&T, and Bright House each stated that they had no
subscribers at all in the District of Columbia; indeed, they do
not even offer service here. The providers also argued that
any burden was necessarily undue because AF Holdings had
failed to provide any reason to think that joinder of these
1,058 defendants in one action was proper.

     The district court rejected these arguments, holding that
“considerations of personal jurisdiction and joinder are
premature when discovery is sought before the plaintiff has
named a defendant and the discovery is targeted to identify
unknown individuals associated with the IP addresses.” But
acknowledging that several other district courts had reached
contrary conclusions in similar situations, and recognizing
that a substantial ground for difference of opinion existed, the
district court certified its order for immediate appeal. See 28
U.S.C. § 1292(b).

     The providers now reiterate the arguments they made in
the district court—that the subpoenas are unduly burdensome
because venue is improper, personal jurisdiction over these
Doe defendants is lacking, and the defendants could not
properly be joined together in one action. Our review is for
abuse of discretion. See Recording Industry Ass’n of America,
Inc. v. Verizon Internet Services, 351 F.3d 1229, 1233 (D.C.
Cir. 2003). As a “district court by definition abuses its
discretion when it makes an error of law,” the “abuse-of-
discretion standard includes review to determine that the
discretion was not guided by erroneous legal conclusions.”
Koon v. United States, 518 U.S. 81, 100 (1996).
                                7
                                II.
    We begin with personal jurisdiction, along with the
closely related question of venue. Defending the district
court’s decision, AF Holdings contends that any consideration
of such issues is premature where, as here, the as-yet-
unknown defendants have yet to raise these defenses. It relies
primarily on Anger v. Revco Drug Co., 791 F.2d 956 (D.C.
Cir. 1986), in which we reiterated the general rule that
“personal jurisdiction is a matter to be raised by motion or
responsive pleading.” Id. at 958.

     In Anger, however, we faced a situation very different
from the one we confront here. There, we considered a district
court’s sua sponte dismissal of a complaint for lack of
personal jurisdiction. We held that such a dismissal is
improper because “before the complaint has been served and
a response received, the court is not positioned to determine
conclusively whether personal jurisdiction exists.” Id.
(emphasis added). In other words, to bring an action a
plaintiff has no obligation to establish personal jurisdiction
until the defendant has raised that defense. See id.; accord,
e.g., Caribbean Broadcasting System, Ltd. v. Cable &
Wireless PLC, 148 F.3d 1080, 1090 (D.C. Cir. 1998) (CBS)
(“CBS’s obligation to make some allegations relating to
personal jurisdiction arose . . . only after CCC had filed its
motion to dismiss . . . .”).

       Different principles apply where, as here, a plaintiff seeks
not just to file a complaint, but instead attempts to use the
machinery of the courts to force a party to comply with its
discovery demands. Federal Rules of Civil Procedure 45 and
26 set forth the relevant considerations. Rule 45(d)(3)(A)
requires a district court to “quash or modify a subpoena that
. . . subjects a person to undue burden.” If a subpoena compels
disclosure of information that is not properly discoverable,
                               8
then the burden it imposes, however slight, is necessarily
undue: why require a party to produce information the
requesting party has no right to obtain? The question then
becomes what sort of information is properly discoverable.
Where, again as here, no party has yet been specifically
named as a defendant, the only potential avenue for discovery
is Rule 26(d)(1), which provides for discovery “by court
order.” A district court’s discretion to order discovery in these
circumstances is, in turn, cabined by Rule 26(b)(1)’s general
requirements that a discovery order be “[f]or good cause” and
relate to a “matter relevant to the subject matter involved in
the action.” See Food Lion v. United Food & Commercial
Workers Union, 103 F.3d 1007, 1012 (D.C. Cir. 1997) (“[N]o
one would suggest that discovery should be allowed of
information that has no conceivable bearing on the case.”
(internal quotation marks omitted)).

     The limits of the federal discovery procedures are
illustrated by Oppenheimer Fund, Inc. v. Sanders, 437 U.S.
340 (1978), in which the Supreme Court held that the
representative plaintiffs in a class action suit could not use
discovery tools to secure from the defendant the names of
members of the plaintiff class. Id. at 353. The Court
concluded that because the plaintiffs did “not seek this
information for any bearing that it might have on issues in the
case,” but instead simply in order to provide the class
members with notice of the litigation, they lacked a proper
discovery purpose. Id. at 352. It inferred this improper motive
in part from the plaintiffs’ conduct in the district court, where
they had offered to redefine the class to encompass only those
class members to whom they could already send notice. See
id. at 353. In a footnote, the Court emphasized—in language
especially relevant here—that “when the purpose of a
discovery request is to gather information for use in
                                9
proceedings other than the pending suit, discovery properly is
denied.” Id. at 352 n.17.

     Applying these same principles, we conclude that, as is
the case when a plaintiff seeks jurisdictional discovery with
respect to named defendants, a plaintiff pursuing discovery of
the sort AF Holdings seeks regarding unknown defendants
must “have at least a good faith belief that such discovery will
enable it to show that the court has personal jurisdiction over
the defendant[s].” CBS, 148 F.3d at 1090. Absent such a
threshold showing, there is little reason to believe that the
information sought will be “relevant to the subject matter
involved in the action,” as Rule 26(b)(1) requires. The
identity of prospective defendants who cannot properly be
sued in this district can be of little use in a lawsuit brought in
this district. And again, as the Court stated in Oppenheimer,
“when the purpose of a discovery request is to gather
information for use in proceedings other than the pending
suit, discovery properly is denied.” 437 U.S. at 352 n.17
(emphasis added). Thus, in denying discovery where there is
no such good faith belief, a court would not be making an
impermissible “conclusive[]” determination on the merits of
the personal jurisdiction question. Anger, 791 F.2d at 958.
Instead, the court would be satisfying its Rule 26 obligation to
ensure that the scope of discovery is limited to issues actually
relevant to the litigation.

    Here, we think it quite obvious that AF Holdings could
not possibly have had a good faith belief that it could
successfully sue the overwhelming majority of the 1,058 John
Doe defendants in this district. AF Holdings concedes that
under the District of Columbia’s long-arm statute, which
along with the Due Process Clause governs this question, see
GTE New Media Services Inc. v. Bellsouth Corp., 199 F.3d
1343, 1347 (D.C. Cir. 2000), the only conceivable way that
                              10
personal jurisdiction might properly be exercised over these
Doe defendants is if they are residents of the District of
Columbia or at least downloaded the copyrighted work in the
District. See D.C. Code § 13-423(3), (4) (providing for
personal jurisdiction over a person “causing tortious injury in
the District of Columbia”); Nu Image, Inc. v. Does 1–23,322,
799 F. Supp. 2d 34, 38–40 (D.D.C. 2011). But AF Holdings
has made absolutely no effort to limit its suit or its discovery
efforts to those defendants who might live or have
downloaded Popular Demand in the District of Columbia.
Instead, it sought to subpoena Internet service providers that
provide no service at all in the District. As Duffy reluctantly
conceded at oral argument, AF Holdings could have no
legitimate reason for objecting to the court’s quashing the
subpoenas directed at these providers. Oral Arg. Rec. 33:00–
04. Even for those providers that do serve the District of
Columbia, AF Holdings’s discovery demands were overbroad
because it made no attempt to limit its inquiry to those
subscribers who might actually be located in the District. It
could have easily done so using what are known as
geolocation services, which enable anyone to estimate the
location of Internet users based on their IP addresses. Such
services cost very little or are even free. See Amicus Br. of
Electronic Frontier Foundation, et al. 24 (observing that
“Neustar IP Intelligence . . . provides on-demand geolocation
services for $8 per 1,000 addresses); see also
http://freegeoip.net (last visited May 22, 2014) (providing this
service for free). While perhaps not precise enough to identify
an Internet user’s street address, these services “can be
accurate,” as Duffy acknowledged at oral argument, Oral Arg.
Rec. 23:58–24:01—certainly sufficiently accurate to provide
at least some basis for determining whether a particular
subscriber might live in the District of Columbia rather than,
say, Oregon, see Nu Image, 799 F. Supp. 2d at 41 (“while
these geolocation services are not 100% accurate, these
                               11
services can place a user no farther away than a city that
borders the user’s actual location”). Given AF Holdings’s
failure to take even these minimal steps, we cannot escape the
conclusion that it sought the vast majority of this information
for reasons unrelated to its pursuit of this particular lawsuit.
See Oppenheimer, 437 U.S. at 352 n.17 (“In deciding whether
a request comes within the discovery rules, a court is not
required to blind itself to the purpose for which a party seeks
information.”). Indeed, Duffy essentially admitted as much at
oral argument, stating that if, as appears to be the case, 399 of
Comcast’s 400 identified subscribers were found to live
outside the District, “the 399 likely wouldn’t be named as
defendants in this case.” Oral Arg. Rec. 34:32–36.

     The foregoing analysis applies equally to venue. Under
the relevant statute, 28 U.S.C. § 1400(a), the propriety of
venue turns on whether the defendant is subject to personal
jurisdiction. See Milwaukee Concrete Studios, Ltd. v. Fjeld
Manufacturing Co., 8 F.3d 441, 445 (7th Cir. 1993) (“section
1400(a)’s ‘may be found’ clause has been interpreted to mean
that a defendant is amenable to personal jurisdiction in a
particular forum”). AF Holdings’s failure to establish any
basis for thinking the latter exists means that it has likewise
failed to set forth any good faith basis for the former.

     AF Holdings’s sole counterargument is that personal
jurisdiction and venue may be waived and that these
defendants, once identified, might do so. See Anger, 791 F.2d
at 958. Such a speculative possibility is, however, plainly
insufficient to satisfy AF Holdings’s obligation to
demonstrate a good faith belief that it will actually be able to
successfully sue the more than a thousand non-District
residents about whom it seeks discovery. As then-District
Judge Robert Wilkins concluded in rejecting the same
argument, “it defies common sense for the Court to assume
                              12
that all of the nonresident John Does will waive viable lack of
venue and lack of personal jurisdiction defenses—indeed,
those defenses have been routinely raised in other similar file
sharing lawsuits.” Nu Image, 799 F. Supp. 2d at 42; see also,
e.g., AF Holdings LLC v. Does 1–96, No. C-11-03335, 2011
U.S. Dist. LEXIS 134655, at *9 (N.D. Cal. 2011) (providing
for discovery only after holding that plaintiff had “made a
prima facie showing that its Complaint would withstand a
motion to dismiss for lack of personal jurisdiction”);
Millenium TGA v. Doe, No. 10-C-5603, 2011 U.S. Dist.
LEXIS 110135, at *8 (N.D. Ill. 2011) (refusing to allow
discovery where there was no plausible basis for personal
jurisdiction); cf. McLaughlin v. Bradlee, 803 F.2d 1197, 1205
(D.C. Cir. 1986) (upholding award of sanctions where
defendants’ issue preclusion defenses were sufficiently
obvious to render complaint frivolous).

      In sum, AF Holdings’s refusal to cabin its suit and
corresponding discovery requests to individuals whom it has
some realistic chance of successfully suing in this district
demonstrates that it has not “sought the information because
of its relevance to the issues” that might actually be litigated
here. Oppenheimer, 437 U.S. at 353. Although AF Holdings
might possibly seek discovery regarding individual
defendants in the judicial districts in which they are likely
located, what it certainly “may not do . . . is improperly use
court processes by attempting to gain information about
hundreds of IP addresses located all over the country in a
single action, especially when many of those addresses fall
outside of the court’s jurisdiction.” Pacific Century
International, Ltd. v. Does 1–37, 282 F.R.D. 189, 196 (N.D.
Ill. 2012). In seeking such information, AF Holdings clearly
abused the discovery process.
                               13
                              III.
     We turn to the question of joinder, which provides a
separate and independent ground for reversal. As relevant
here, Federal Rule of Civil Procedure 20(a)(2) sets forth that
multiple defendants may be joined in one action if the
plaintiff seeks relief “with respect to or arising out of the
same transaction, occurrence, or series of transactions or
occurrences” and “any question of law or fact common to all
defendants will arise in the action.” In a multi-Doe copyright
infringement lawsuit such as this, at least one issue of law or
fact will generally be common to all defendants—here, that
issue might be whether AF Holdings has a valid copyright in
Popular Demand. But whether all of these Doe defendants
could possibly have been a part of the same “transaction,
occurrence, or series of transactions or occurrences” so as to
support joinder is a more difficult question. If a plaintiff such
as AF Holdings can claim no good faith belief that all the Doe
defendants are linked in this way, then the logic for denying
or at least limiting discovery is the same as that delineated
above with respect to personal jurisdiction and venue:
information about individuals who could not be joined in an
action cannot possibly be “relevant to the subject matter
involved in the action.” Fed. R. Civ. P. 26(b)(1).

     According to AF Holdings, joinder of the 1,058 John
Does it named in the underlying suit was at least
presumptively proper because, given the properties of the
BitTorrent file-sharing protocol the defendants allegedly used
to download Popular Demand, each defendant was
necessarily part of the same transaction or series of
transactions. Some background on the nature of BitTorrent is
necessary to understand this argument. As Judge Harold Baer,
considering a case very much like this one, explained:
                             14
    Simplified, BitTorrent and similar protocols break a
    large file into pieces while tagging each piece with a
    common identifier. Where in the normal course a
    user would download a file from a single source, and
    download it sequentially from beginning to end, with
    the BitTorrent peer-to-peer protocol, users join
    forces to simultaneously download and upload pieces
    of the file from and to each other. This reduces the
    bottleneck of Internet traffic that normally occurs at
    the server where the entire file is located and allows
    for faster download speeds for users. This
    interconnected web of information flowing between
    users, or peers, is called a swarm.

Media Products, Inc. v. Does 1–26, No. 12 Civ. 3719, 2012
U.S. Dist. LEXIS 125366, at *4 (S.D.N.Y. Sept. 3, 2012). AF
Holdings argues that because BitTorrent users who download
the same file are part of the same “swarm,” they have all
participated in the same series of transactions. See, e.g.,
Digital Sin, Inc. v. Does 1–176, 279 F.R.D. 239, 244
(S.D.N.Y. 2012) (accepting a version of this argument).

     We are unconvinced. For purposes of this case, we may
assume that two individuals who participate in the same
swarm at the same time are part of the same series of
transactions within the meaning of Rule 20(a)(2). In that
circumstance, the individuals might well be actively sharing a
file with one another, uploading and downloading pieces of
the copyrighted work from the other members of the swarm.

     But AF Holdings has provided no reason to think that the
Doe defendants it named in this lawsuit were ever
participating in the same swarm at the same time. Instead, it
has simply set forth snapshots of a precise moment in which
each of these 1,058 Does allegedly shared the copyrighted
                               15
work—snapshots that span a period of nearly five months.
Two individuals who downloaded the same file five months
apart are exceedingly unlikely to have had any interaction
with one another whatsoever. Their only relationship is that
they used the same protocol to access the same work. To
paraphrase an analogy offered by amicus counsel at oral
argument, two BitTorrent users who download the same file
months apart are like two individuals who play at the same
blackjack table at different times. They may have won the
same amount of money, employed the same strategy, and
perhaps even played with the same dealer, but they have still
engaged in entirely separate transactions. And “[s]imply
committing the same type of violation in the same way does
not link defendants together for the purposes of joinder.”
Hard Drive Productions, Inc. v. Does 1–30, No. 2:11cv345,
2011 U.S. Dist. LEXIS 119333, at *7 (E.D. Va. 2011)
(internal quotation marks omitted). We therefore agree with
those district courts that have concluded that the mere fact
that two defendants accessed the same file through BitTorrent
provides an insufficient basis for joinder. See Malibu Media
LLC, 286 F.R.D. 113, 116 (D.D.C. 2012) (“‘Nothing in the
complaint negates the inference that the downloads by the
various [Doe] defendants were discrete and separate acts that
took place at different times.’”) (quoting Digital Sins, Inc. v.
Does 1–245, No. 11 Civ. 8170, 2012 U.S. Dist. LEXIS
69286, at *6 (S.D.N.Y. 2012)); accord, e.g., Patrick Collins,
Inc. v. Does 1–44, No. 8:12-cv-00020, 2012 U.S. Dist. LEXIS
47686, at *18 (D. Md. Apr. 4, 2012) (“A majority of courts
. . . have specifically held that the properties of BitTorrent are
insufficient to support joinder.”); In re BitTorrent Adult Film
Copyright Infringement Cases, 296 F.R.D. 80, 90–91
(E.D.N.Y. 2012).

    As with personal jurisdiction and venue, AF Holdings
could have brought a suit for which it had some reasonable
                               16
basis for believing that the requirements for joinder would be
satisfied. But given its decision to instead name and seek
discovery regarding a vast number of defendants who
downloaded the film weeks and even months apart—
defendants who could not possibly remain joined in this
litigation—one can easily infer that its purpose was to attain
information that was not, and could not be, relevant to this
particular suit. Such use of the discovery procedures is
prohibited.

                              IV.
    Accordingly, we vacate the district court’s order and
remand for further proceedings consistent with this opinion.
We leave it to the district court to determine what sanctions, if
any, are warranted for AF Holdings’s use of a possible
forgery in support of its claim.

                                                    So ordered.
