  United States Court of Appeals
      for the Federal Circuit
                ______________________

             ANZA TECHNOLOGY, INC.,
                 Plaintiff-Appellant

                           v.

   MUSHKIN, INC., DBA ENHANCED NETWORK
                SYSTEMS, INC.,
               Defendant-Appellee
             ______________________

                      2019-1045
                ______________________

    Appeal from the United States District Court for the
District of Colorado in No. 1:17-cv-03135-MEH, Magistrate
Judge Michael E. Hegarty.
                  ______________________

               Decided: August 16, 2019
                ______________________

   COLBY BRIAN SPRINGER, Polsinelli LLP, San Francisco,
CA, argued for plaintiff-appellant. Also represented by
MIYA YUSA; MICHAEL DULIN, Denver, CO; HANNAH
THERESA YANG, Kilpatrick Townsend & Stockton LLP, San
Francisco, CA.

   D. SCOTT HEMINGWAY, Hemingway & Hansen, LLP,
Dallas, TX, argued for defendant-appellee. Also repre-
sented by THOMAS S. RICE, Senter Goldfarb & Rice LLC,
Denver, CO.
                ______________________
2                     ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.




      Before PROST, Chief Judge, NEWMAN and BRYSON,
                     Circuit Judges.

BRYSON, Circuit Judge.
         Plaintiff Anza Technology, Inc., (“Anza”) appeals
from a decision of the United States District Court for the
District of Colorado granting a motion by defendant Mush-
kin, Inc., dba Enhanced Network Systems, Inc., (“Mush-
kin”) to dismiss Anza’s second amended complaint. The
dismissal followed from the court’s finding that Anza’s
claim of damages for patent infringement was barred by
the six-year statute of limitations in the Patent Act, 35
U.S.C. § 286. That ruling was based in turn on the court’s
determination that the claims in Anza’s second amended
complaint did not relate back to the date of Anza’s original
complaint and were therefore time-barred. Because the
district court’s application of the relation back doctrine was
overly restrictive, we reverse in part, vacate in part, and
remand for further proceedings.
                              I
                              A
    Anza filed this action on March 28, 2017, in the United
States District Court for the Eastern District of California,
alleging that Mushkin had infringed claims 1, 14, and 16
of Anza’s U.S. Patent No. 7,124,927 (“the ’927 patent”), in
violation of 35 U.S.C. § 271(a) and (g). The ’927 patent,
entitled “Flip Chip Bonding Tool and Ball Placement Ca-
pillary,” relates to “dissipative and insulative ceramic flip
chip bonding tools and capillaries for ball placement for
bonding electrical connections.” ’927 patent, col. 1, ll. 39–
41.
    The specification of the ’927 patent discusses two tech-
niques for bonding electronic components, such as semicon-
ductor integrated circuit (“IC”) chips, to substrates, circuit
ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.                         3



boards, or carriers. The two techniques are referred to as
“wire bonding” and “flip chip bonding.” ’927 patent, col. 1,
ll. 60–65. In wire bonding, the chip is oriented face-up, so
that there is no direct electrical connection between the
leads of the chip and the bond pads on the substrate. A
wire is then used to connect the chip to the substrate. Id.
at col. 1, ll. 43–61. In flip chip bonding, the chip is oriented
face-down, which allows for a direct electrical connection
between the chip and the substrate. The direct electrical
connection is facilitated by conductive solder balls that are
deposited on the chip; the solder balls provide the conduc-
tive path from chip to substrate. Id. at col. 1, ll. 61–65; col.
2, ll. 9–10; Fig. 3.
     Under either technique, the bonding process requires
the use of bonding tools. The ’927 patent explains that the
problem with prior art bonding tools was that “an electro-
static discharge (ESD) from the bonding tool or transient
currents from the machine [that uses the tool] can damage
the very circuit the tool is bonding.” Id. at col. 2, ll. 47–49.
According to the specification, “[c]ertain prior art devices
have a one-or-more volt emission when the tip makes bond-
ing contact. This could present a problem, as a one-volt
static discharge can . . . cause the integrated circuit to fail.”
Id. at col. 2, ll. 53–59.
    To avoid damage to the electronic devices from such an
electrostatic discharge, the ’927 patent recites a bonding
tool tip for flip chip bonding that “conducts electricity at a
rate sufficient to prevent charge buildup but not at so high
a rate as to overload the device being bonded.” Id. at col. 2,
line 67, through col. 3, line 2.
    Claims 1, 14, and 16 of the ’927 patent, all independent
claims, recite a system, a component, and a method, respec-
tively. Claim 1 provides as follows:
    1. A flip chip bonding tool and ball placement capil-
    lary system for connecting leads on integrated
4                    ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.




    circuit bonding pads, comprising a dissipative ma-
    terial having a resistance low enough to prevent a
    discharge of a charge to a device being bonded and
    high enough to stop current flow large enough to
    damage the device being bonded.
Claim 14 recites:
    14. An ESD-preventive device comprising:
    a flip chip bonding tool and ball placement capil-
    lary, comprising a dissipative material and config-
    ured to come in contact with a device being bonded,
    wherein a current produced by static charge gener-
    ated during bonding is allowed to flow; wherein the
    dissipative material has a resistance low enough to
    prevent a discharge of charge to the device being
    bonded and high enough to stop all current flow to
    the device being bonded.
Claim 16 recites “[a] method of utilizing a flip chip bonding
tool . . . in a microelectronic assembly.” The claimed
method recites the use of a bonding machine capable of be-
ing equipped with a flip chip bonding tool, which has a tip
comprising a dissipative material having the same proper-
ties as recited in claims 1 and 14.
                             B
    On September 6, 2017, Anza filed its first amended
complaint, which joined Avant Technology, Inc., as a co-de-
fendant. 1 Thereafter, Mushkin filed a motion to dismiss or


    1 The first amended complaint alleged that Avant was
“the sole aggregator of all Mushkin-based memory modules
and board products . . . by virtue of Avant having acquired
certain assets of Defendant Mushkin in accordance with an
asset purchase agreement dated April 1, 2012.” Because
there is no material difference between the original com-
plaint and the first amended complaint for purposes of the
ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.                     5



to sever the claims against Mushkin from those against
Avant, and either to stay the case against Mushkin or to
transfer the case to the District of Colorado. The California
district court severed Anza’s claims against Mushkin and
transferred the case against Mushkin to the District of Col-
orado.
    Following the transfer, Anza served infringement con-
tentions against Mushkin pursuant to the District of Colo-
rado’s Local Patent Rules 4 and 5. The infringement
contentions accused Mushkin of directly infringing claims
1 and 14, but did not refer to claim 16. Noting in its in-
fringement contentions that discovery had not commenced
and a formal scheduling order had not been entered, Anza
stated that it reserved “the right to supplement these con-
tentions as appropriate based upon further discovery and
the schedule of this case, including but not limited to as-
sertions related to new claims and/or patents as may be al-
lowed through amendment of the operative pleading.”
    The parties then engaged in mediation. In the course
of the mediation, Mushkin provided Anza with a declara-
tion of George Stathakis, Mushkin’s president, regarding
the technology used by Mushkin. The Stathakis declara-
tion stated, inter alia, that Mushkin “did not bond IC chips
to boards or modules.” Instead, according to the declara-
tion, “[t]he memory products purchased by Mushkin, Inc.
from suppliers were IC memory chips that were al-
ready . . . bonded on printed circuit boards or memory mod-
ule boards.” Additionally, the declaration stated that
Mushkin’s supplier “does not place or position solder ball
connectors on the IC chip for use in bonding the IC chip to
a printed circuit board or memory module board.”




issues in this case, we focus on the differences between the
original complaint and the second amended complaint.
6                     ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.




    The district court held a hearing to address Mushkin’s
motion to dismiss. In light of information in the Stathakis
declaration, Anza “agreed that its present claims [were] no
longer viable.” Based on that concession, the district court
granted Mushkin’s motion. However, the court ruled that
Anza would be permitted to file an amended complaint and
that Mushkin would be allowed to file a motion to dismiss
that complaint.
                              C
    Anza filed its second amended complaint on June 8,
2018. In the second amended complaint, Anza removed the
infringement allegations regarding the ’927 patent and al-
leged infringement of two new patents: U.S. Patent Nos.
6,354,479 (“the ’479 patent”) and 6,651,864 (“the ’864 pa-
tent”). The new complaint alleged that Mushkin had in-
fringed those patents under 35 U.S.C. § 271(g). Anza also
omitted ten of the sixteen products that had been accused
in the original complaint and added two new products that
had not previously been accused.
     The ’479 and ’864 patents, entitled “Dissipative Ce-
ramic Bonding Tip” and “Dissipative Ceramic Bonding Tool
Tip,” respectively, claim priority to the same U.S. provi-
sional application as the ’927 patent. Like the ’927 patent,
the ’479 and ’864 patents recite the use of “dissipative ce-
ramic bonding tips for bonding electrical connections.” ’479
patent, col. 1, ll. 12–13; ’864 patent, col. 1, ll. 20–21. The
patents offer the same solution to the problem of electro-
static discharge damage during the bonding process—
providing a bonding tool tip that conducts electricity “at a
rate sufficient to prevent charge buildup, but not at so high
a rate as to overload the device being bonded.” ’479 patent,
col. 2, ll. 4–6; ’864 patent, col. 2, ll. 11–13. The ’479 and
’864 patents differ from the ’927 patent in that they are di-
rected to bonding tool tips for wire bonding, rather than for
flip chip bonding. In addition, in contrast to the system
ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.                      7



and component claims of the ’927 patent, the asserted
claims of the ’479 and ’864 patents (claims 39 and 28, re-
spectively), are method claims. Claim 37 of the ’479 patent,
from which asserted claim 39 depends, recites as follows:
    37. A method of using a bonding tip, comprising:
    bonding a device using a bonding tip made with a
    dissipative material that has a resistance low
    enough to prevent a discharge of charge to said de-
    vice and high enough to avoid current flow large
    enough to damage said device.
Similarly, independent claim 28 of the ’864 patent recites:
    28. A method of using an electrically dissipative
    bonding tool tip, having a resistance in the range of
    105 to 1012 ohms, comprising:
    providing the electrically dissipative bonding tool
    tip;
    bonding a material to a device;
    allowing an essentially smooth current to dissipate
    to the device, the current being low enough so as
    not to damage said device being bonded and high
    enough to avoid a build up of charge that could dis-
    charge to the device being bonded and damage the
    device being bonded.
                              D
    Mushkin filed a motion to dismiss the second amended
complaint. It argued, inter alia, that the new patent claims
against Mushkin do not relate back to the date of Anza’s
original complaint. In support of that argument, Mushkin
relied on Rule 15(c)(1)(B) of the Federal Rules of Civil Pro-
cedure, which provides: “An amendment to a pleading re-
lates back to the date of the original pleading when . . . the
amendment asserts a claim or defense that arose out of the
8                     ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.




conduct, transaction, or occurrence set out—or attempted
to be set out—in the original pleading.”
    The district court granted Mushkin’s motion, ruling
that the new infringement claims did not relate back to the
date of the original complaint. The court explained that
new infringement claims relate back to the date of the orig-
inal complaint when the claims involve the same parties,
the same products, and similar technology—i.e., when the
claims are “part and parcel” of the original complaint. The
court ruled that newly asserted claims of infringement do
not relate back if the new claims are not an integral part of
the claims in the original complaint and if proof of the new
claims will not entail the same evidence as proof of the orig-
inal claims.
     With respect to the patent claims asserted in the origi-
nal complaint as compared with those asserted in the sec-
ond amended complaint, the district court found that
“[a]lthough the claims involve the same parties, they do not
relate to identical products and technology.” Comparing
the ’864 and ’479 patents with the ’927 patent, the district
court found that the asserted claims of the ’864 and ’479
patents “protect a method of using a wire bonding tool,
while the ’927 claims involved a flip chip bonding and sol-
der ball placement tool.” The district court acknowledged
that the patent claims have the “same purpose—bonding
integrated circuit chips to printed circuit boards while min-
imizing electrostatic discharge.” But because it found that
“different processes and technologies are used to achieve
this purpose,” the district court held that the patent claims
are “not part and parcel of one another.” As for the accused
products, the court noted that the second amended com-
plaint added two new accused products and omitted a
ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.                    9



number of accused products as compared with the original
complaint. 2
    The district court added that “proving infringement of
the initial and new claims would not involve substantially
the same evidence.” The district court explained:
   Proving the ’927 patent claims would require evi-
   dence of the flip chip bonding method and how the
   flip chip bonding and ball placement tool was used
   in making the allegedly infringing products. Con-
   versely, proving the newly asserted claims requires
   evidence of the wire bonding process and how a
   wire bonding tool tip was used to produce the alleg-
   edly infringing products.
In particular, the court noted, the new claims would entail
different evidence because Anza’s infringement conten-
tions had dropped claim 16 of the ’927 patent, which the
district court considered to be the claim from the first
amended complaint that was most similar to the newly as-
serted claims.
    The district court then addressed the effect of its rul-
ings on the statute of limitations for patent claims, 35
U.S.C. § 286, which bars recovery for any infringement
“committed more than six years prior to the filing of the
complaint or counterclaim for infringement in the action.”


   2  The district court misspoke with regard to the num-
ber of accused products omitted from the second amended
complaint. The court stated that the second amended com-
plaint omitted eleven of the products that were accused in
the original complaint, but in fact the number of omitted
products was ten. Compare Second Amended Complaint at
13, Anza Tech., Inc. v. Mushkin, Inc., No. 1:17-cv-03135-
MEH (D. Colo. June 8, 2018), ECF No. 75, with Complaint
at 6–7, Anza Tech., Inc. v. Mushkin, Inc., No. 1:17-cv-
03135-MEH (D. Colo. Mar. 28, 2017), ECF No. 1.
10                    ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.




Because Anza acknowledged that Mushkin’s allegedly in-
fringing activity all took place more than six years before
the filing date of the second amended complaint, the court
held that the effect of ruling that the second amended com-
plaint did not relate back to the filing date for the original
complaint was that all the asserted claims in the second
amended complaint were time-barred.
                              II
                              A
    A preliminary question is whether Federal Circuit law,
rather than regional circuit law, governs whether newly al-
leged claims in an amended complaint relate back to the
date of the original complaint when the new claims are
based on newly asserted patents.
    We have previously held that “[a] procedural issue that
is not itself a substantive patent law issue is nonetheless
governed by Federal Circuit law if the issue pertains to pa-
tent law, if it bears an essential relationship to matters
committed to our exclusive control by statute, or if it clearly
implicates the jurisprudential responsibilities of this court
in a field within its exclusive jurisdiction.” O2 Micro Int’l
Ltd. v. Monolithic Power Sys., Inc., 467 F.3d 1355, 1364
(Fed. Cir. 2006) (quoting Midwest Indus., Inc. v. Karavan
Trailers, Inc., 175 F.3d 1356, 1359 (Fed. Cir. 1999)(en banc
in relevant part)).
    One example of such a procedural issue is a motion to
sever in a patent case. We have held that “motions to sever
are governed by Federal Circuit law because joinder in pa-
tent cases is based on an analysis of the accused acts of in-
fringement, and this issue involves substantive issues
unique to patent law.” In re EMC Corp., 677 F.3d 1351,
1354 (Fed. Cir. 2012). As in the case of motions to sever,
the determination of whether newly alleged infringement
claims relate back to the original complaint also turns on
ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.                      11



“an analysis of the accused acts of infringement.” Id.
Therefore, we hold that this determination is also governed
by Federal Circuit law.
                              B
    The next question is what standard governs this court’s
review of a district court’s application of the relation back
doctrine.
    Anza argues that this court should apply a de novo
standard of review. Anza bases that argument on the fact
that the district court dismissed the second amended com-
plaint after holding the relation back doctrine inapplicable,
and that dismissals of a complaint under Fed. R. Civ. P.
12(b)(6) are subject to de novo review.
     The problem with Anza’s argument is that the dismis-
sal in this case was the necessary consequence of the
court’s determination that the relation back doctrine does
not apply, since without the benefit of the relation back
doctrine, it is clear that the statute of limitations would bar
all of Anza’s claims against Mushkin. What Anza is chal-
lenging is not the dismissal itself, but whether the district
court properly applied the relation back doctrine under
Rule 15(c). The standard of review that applies to a dis-
missal under Rule 12(b)(6) therefore has nothing to do with
the critical issue in this case, which is whether the court
properly determined not to apply the relation back doctrine
to the second amended complaint. For that reason, Anza’s
argument sheds no light on what standard should be ap-
plied in reviewing that issue.
    Mushkin argues that the district court’s ruling on the
relation back issue should be reviewed under the abuse of
discretion standard. In arguing for that standard, Mush-
kin relies on two decisions of this court, but the cases
Mushkin cites do not support its argument. In the first
case, Fromson v. Citiplate, Inc., the court merely stated
that it found “no reversible error” in the district court’s
12                   ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.




conclusion that the amended complaint related back to the
date of the original complaint. 886 F.2d 1300, 1304 (Fed.
Cir. 1989). The court did not specify what standard of re-
view it applied in reaching that conclusion. The second
case, Datascope Corp. v. SMEC, Inc., 962 F.2d 1043 (Fed.
Cir. 1992), did not deal with the relation back doctrine at
all. The court in that case merely held that the district
court’s refusal to permit amendment of the complaint was
not an abuse of discretion. Id. at 1047. While Datascope
applied the abuse of discretion standard to the question
whether the district court erred in denying a motion to
amend a complaint under Fed. R. Civ. P. 15(a), nothing in
Datascope speaks to the standard of review to be applied to
the separate question of whether an amended pleading re-
lates back to the date of the original pleading under Fed.
R. Civ. P. 15(c).
    Mushkin’s suggestion that we review the district
court’s relation back ruling under an abuse of discretion
standard would be contrary to the law of most of the other
circuits, which have adopted a de novo standard when re-
viewing decisions regarding whether an amended pleading
relates back to the date of the original pleading. See Glover
v. FDIC, 698 F.3d 139, 144 (3d Cir. 2012); Robinson v.
Clipse, 602 F.3d 605, 607 (4th Cir. 2010); Slayton v. Am.
Express Co., 460 F.3d 215, 227–28 (2d Cir. 2006); Young v.
Lepone, 305 F.3d 1, 14 (1st Cir. 2002); Miller v. Am. Heavy
Lift Shipping, 231 F.3d 242, 246–47 (6th Cir. 2000); Del-
gado-Brunet v. Clark, 93 F.3d 339, 342 (7th Cir. 1996);
Slade v. U.S. Postal Serv., 875 F.2d 814, 815 (10th Cir.
1989); Percy v. S.F. Gen. Hosp., 841 F.2d 975, 978 (9th Cir.
1988). Contra Powers v. Graff, 148 F.3d 1223, 1226 (11th
Cir. 1998) (application of Rule 15(c) is reviewed for abuse
of discretion, while findings of fact necessary for applica-
tion of the rule are reviewed for clear error ).
    We adopt the majority rule. The rationale underlying
that rule, when it has been expressed, is that the de novo
ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.                       13



standard of review applies because determining whether
the amended claim “arose out of the conduct, transaction,
or occurrence” set forth in the original complaint requires
the reviewing court to apply the legal standard of Rule
15(c) “to a given set of facts,” which is “a task we are no less
suited to perform than the district court.” Miller, 231 F.3d
at 247; accord Percy, 841 F.2d at 978; Lundy v. Adamar of
N.J., Inc., 34 F.3d 1173, 1177 (3d Cir. 1994). In some in-
stances, however, factual issues may need to be addressed
as part of the district court’s analysis of the relation back
issue. With respect to any disputed facts that are material
to the relation back issue, we are not as well situated as
the district court to make the appropriate findings. There-
fore, in the event that such factual issues arise, we would
review any findings by the district court on those issues for
clear error, as we do in analogous circumstances. See, e.g.,
Presidio Components, Inc. v. Am. Tech. Ceramics Corp., 875
F.3d 1369, 1375 (Fed. Cir. 2017) (indefiniteness); Par
Pharm., Inc. v. TWI Pharm., Inc., 773 F.3d 1186, 1194 (Fed.
Cir. 2014) (obviousness); Alcon Research Ltd. v. Barr Labs.,
Inc., 745 F.3d 1180, 1188 (Fed. Cir. 2014) (enablement);
SanDisk Corp. v. STMicroelectronics, Inc., 480 F.3d 1372,
1377 (Fed. Cir. 2007) (presence of a case or controversy);
Rambus Inc. v. Infineon Techs. AG, 318 F.3d 1081, 1087–
88 (Fed. Cir. 2003) (attorney fee award); In re Emert, 124
F.3d 1458, 1460 (Fed. Cir. 1997) (double patenting).
                               C
    The Supreme Court has interpreted the relation back
doctrine liberally, to apply if an amended pleading “re-
late[s] to the same general conduct, transaction and occur-
rence” as the original pleading. Tiller v. Atl. Coast Line
R.R. Co., 323 U.S. 574, 580–81 (1945) (holding, in a rail-
road negligence case that even though the amended com-
plaint alleged a different theory of negligence, the new
charge related back to the original complaint because “[t]he
cause of action now, as it was in the beginning, is the
14                    ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.




same—it is a suit to recover damages for the alleged wrong-
ful death of the deceased.”). That liberal interpretation of
the relation back rule reflects the rationale of Rule 15(c),
which is that “a party who has been notified of litigation
concerning a particular occurrence has been give all the no-
tice that statutes of limitations were intended to provide.”
Baldwin Cty. Welcome Ctr. v. Brown, 466 U.S. 147, 149 n.3
(1984).
    Our predecessor court, the Court of Claims, embraced
that liberal, notice-based interpretation of Rule 15(c). See
Snoqualmie Tribe of Indians v. United States, 372 F.2d
951, 961 (Ct. Cl. 1967) (“A restrictive view would limit ap-
plication of the rule to minor pleading mistakes. We think
modern practice requires a more imaginative approach,
and that [Rule 15(c)] should be read liberally to permit an
amended pleading to relate back where there is sufficient
notice.”); see also Vann v. United States, 420 F.2d 968, 974
(Ct. Cl. 1970) (“The test for determining whether the new
matter in an amended petition arose from the ‘conduct,
transaction, or occurrence’ first pleaded is whether the gen-
eral fact situation or the aggregate of the operative facts
underlying the claim for relief in the first petition gave no-
tice to the [accused party] of the new matter.”); United
States v. N. Paiute Nation, 393 F.2d 786, 790 (Ct. Cl. 1968)
(“Sufficient notice to the Government is the test . . . with
our inquiry focusing on the notice given by the general fact
situation set forth in the original pleading.”) (citations and
footnote omitted)).
    Federal Circuit cases have applied a similar approach
to Rule 15(c). See Korody-Colyer Corp. v. Gen. Motors
Corp., 828 F.2d 1572, 1575 (Fed. Cir. 1987) (“Under Rule
15(c) . . . an amendment may relate back when the earlier
complaint gave adequate notice of the new claim.”); see also
Barron Bancshares, Inc. v. United States, 366 F.3d 1360,
1369–70 (Fed. Cir. 2004); Intrepid v. Pollock, 907 F.2d
1125, 1130 (Fed. Cir. 1990).
ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.                       15



     The notice-based interpretation of Rule 15(c) is con-
sistent with the approach used under Rules 13(a) and 20(a)
of the Federal Rules of Civil Procedure. Those rules, which
share the “same transaction or occurrence” standard used
in Rule 15(c), have been interpreted to require that coun-
terclaims (in the case of Rule 13(a)) or the claims of the
plaintiffs to be joined (in the case of Rule 20(a)) be logically
related to the claims in the original complaint. See In re
EMC Corp., 677 F.3d at 1357–58.
    The “logical relationship” standard contemplates a “lib-
eral approach to the concept of same transaction or occur-
rence.” 7 Charles Alan Wright et al., Federal Practice &
Procedure § 1653, at 410–11 (3d ed. 2001). It asks whether
the facts underlying the alleged claims “share an aggregate
of operative facts.” In re EMC Corp., 677 F.3d at 1359. For
purposes of the logical relationship test, “all logically re-
lated events entitling a person to institute a legal action
against another generally are regarded as comprising a
transaction or occurrence.” 7 Charles Alan Wright et al.,
Federal Practice & Procedure § 1653, at 409.
    In light of the similarity in the language used in Rule
15(c) and Rules 13(a) and 20(a), cases applying the logical
relationship test in the patent context are particularly in-
structive in applying the relation back doctrine. Those
cases suggest that pertinent considerations bearing on
whether claims are logically related include the overlap of
parties, products or processes, time periods, licensing and
technology agreements, and product or process develop-
ment and manufacture. See In re EMC Corp., 677 F.3d at
1359–60; Futurewei Techs., Inc. v. Acacia Research Corp.,
737 F.3d 704, 710 (Fed. Cir. 2013) (“Here, the logical rela-
tionship is strong: the license agreement gives rise to
Huawei’s alter-ego claim, to SmartPhone’s affirmative
right to enforce the patents in the Texas case, and to
Huawei’s defense in that case . . . .”); see also In re Rearden
LLC, 841 F.3d 1327, 1332 (Fed. Cir. 2016) (noting that the
16                    ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.




logical relationship test is one of three tests used to deter-
mine whether the transaction-or-occurrence test is met un-
der Rule 13(a), and finding the counterclaim compulsory
because, inter alia, “the claims and counterclaims share a
close, logical relation: the ownership and rightful use of the
technology claimed and disclosed in the MOVA patents”).
     Several district courts have addressed the issue of
whether newly alleged claims, based on separate patents,
relate back to the date of the original complaint. Most of
those courts have employed a similar analysis, asking
whether the newly asserted patents are “part and parcel”
of the original controversy. For example, in Halo Electron-
ics, Inc. v. Bel Fuse Inc., No. C-07-06222 RMW, 2008 WL
1991094, at *3 (N.D. Cal. May 5, 2008), the court found that
the six Halo patents that were the subjects of the new
claims were not “part or parcel” of the original complaint,
which involved another patent, because “the Halo patents
involve[d] different technologies and products.” On the
other hand, the court in PerfectVision Manufacturing, Inc.
v. PPC Broadband, Inc., 951 F. Supp. 2d 1083, 1093, 1093–
94 (E.D. Ark. 2013), found that the amended complaint re-
lated back to the date of the original complaint, after con-
sidering whether the patents cited in the two complaints
involved “the same field of art, the same fundamental sci-
ence and technology . . . [,] the same allegedly infringing
devices, and, in any damages analysis, the same pricing,
sales, and related market data.”
    Accordingly, in determining whether newly alleged
claims, based on separate patents, relate back to the date
of the original complaint, we will consider the overlap of
parties, the overlap in the accused products, the underlying
science and technology, time periods, and any additional
factors that might suggest a commonality or lack of com-
monality between the two sets of claims. At bottom, how-
ever, the question remains whether the general factual
situation or the aggregate of operative facts underlying the
ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.                    17



original claim for relief gave notice to Mushkin of the na-
ture of the allegations it was being called upon to answer.
                             D
    On appeal, Anza challenges the district court’s conclu-
sion that the second amended complaint did not relate back
to the date of the original complaint. Anza argues that the
’864, ’479, and ’927 patents all seek to solve the same prob-
lem—avoiding damage to delicate devices as a result of
ESD—and that the three patents all employ the same so-
lution to address that problem—using dissipative ceramic
tips on the bonding tools.
    Anza also argues that there is a significant overlap of
properties between the two sets of accused Mushkin prod-
ucts. According to Anza, each accused product in both the
original complaint and the second amended complaint re-
quires the use of certain techniques and methods to guard
against damaging ESD events, which include compliance
with standards that “involve[] the use of manufacturing
tools made of dissipative materials having resistance
ranges low enough to prevent a discharge of a charge to an
ESD sensitive device but high enough to avoid current
flows that may damage the device.”
     Mushkin disagrees. According to Mushkin, the allega-
tions in the second amended complaint are significantly
different from the initial “flip chip” infringement allega-
tions, for several reasons.
    Mushkin first argues that the fact that the second
amended complaint withdrew all prior claims of infringe-
ment under the “flip chip” ’927 patent and substituted
claims from the two “wire bonding” patents indicates that
the two complaints address entirely different bonding tech-
niques. We disagree.
    While the patents address different bonding tech-
niques, they all share the same underlying technology. All
18                     ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.




three patents are focused on solving the same problem by
the same solution, using a bonding tool tip made of a dissi-
pative material having a resistance low enough to prevent
the discharge of a charge to a device being bonded and high
enough to avoid current flow to that device. ’927 patent,
col. 2, line 64, through col. 3, line 2; ’479 patent, col. 2, ll.
3–6; ’864 patent, col. 2, ll. 11–13. Moreover, while the spec-
ifications of the ’479 and ’864 patents discuss only wire
bonding, the asserted claims of those patents are not lim-
ited to the wire bonding technique. Both claim 39 of the
’479 patent and claim 28 of the ’864 broadly recite methods
of using bonding tips more generally.
    The use of bonding tool tips made of a dissipative ma-
terial is the basis for the charges of infringement alleged in
each of the complaints. According to the complaints, indus-
try-recognized standards-setting organizations have set
standards for certain ESD-sensitive devices, including IC
chips, that require the use of manufacturing tools made of
dissipative materials. The complaints thus target products
assembled or manufactured in ways that meet or exceed
industry standards for reducing the risk of damage to ESD-
sensitive devices. This technological overlap suggests that
the aggregate of operative facts underlying infringement
under the ’927 patent in the original complaint gave notice
of the substance of the claims of infringement under the
’479 and ’864 patents in the second amended complaint.
    To be sure, the original complaint differs from the sec-
ond amended complaint in that the original complaint was
limited to products manufactured using flip chip bonding.
But the type of bonding technique is of secondary im-
portance compared with the use of manufacturing tools
made of dissipative material. Contrary to the district
court’s conclusion, proving infringement would only re-
quire evidence that certain bonding tools were used, not ev-
idence as to how those tools were used. That determination
would not be likely to result in a substantially different
ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.                     19



evidentiary showing to prove infringement of the claims as-
serted in the second amended complaint.
     Mushkin next argues that, before the filing of the sec-
ond amended complaint, Anza narrowed its infringement
claims in a way that distinguished its claims from the
claims set forth in its original complaint. In what the dis-
trict court characterized as Anza’s “informal infringement
contentions,” Anza did not assert the previously pleaded 35
U.S.C. § 271(g) statutory basis for infringement, and it did
not assert its previously pleaded allegations regarding
“method of use” claim 16 of the ’927 patent. The infringe-
ment contentions thus asserted only system and compo-
nent claims 1 and 14, and alleged a theory of direct
infringement only under 35 U.S.C. § 271(a). Subsequently,
however, in the second amended complaint, Anza asserted
infringement of “method of use” claims from the two new
patents and alleged infringement under 35 U.S.C. § 271(g).
     In light of this sequence of events, Mushkin argues that
the second amended complaint changed not only the type
of claims asserted, but also the statutory basis for infringe-
ment and the party alleged to have conducted the accused
bonding activity (a shift from Mushkin to an upstream
manufacturer). Those changes between the theory of in-
fringement set forth in the infringement contentions and
allegations in the second amended complaint, according to
Mushkin, show that there were substantial differences be-
tween the new and old claims.
    Mushkin treats the infringement contentions as irre-
versibly narrowing the scope of the original complaint. In
fact, however, Anza asserted that the infringement conten-
tions were “preliminary, and based solely on public infor-
mation.” Moreover, in the infringement contentions, Anza
reserved the right “to supplement the[] contentions as ap-
propriate based upon further discovery and the schedule of
th[e] case.”
20                    ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.




    Apart from Anza’s reservation of the right to supple-
ment, the District of Colorado Local Patent Rules permit
amendments to infringement contentions. According to
Rule 16 of the Local Patent Rules, amendments to the in-
fringement contentions, including the addition of accused
products or processes, are permissible upon a showing of
good cause, such as the discovery of previously undiscov-
ered information. D. Colo. Local Patent Rule 16(a)(3); see
O2 Micro, 467 F.3d at 1366 (“If a local patent rule required
the final identification of infringement and invalidity con-
tentions to occur at the outset of the case, shortly after the
pleadings were filed and well before the end of discovery, it
might well conflict with the spirit, if not the letter, of the
notice pleading and broad discovery regime created by the
Federal Rules.”). The discoveries made as a result of the
Stathakis declaration, including that Mushkin does not
bond IC chips to boards or modules, but instead purchases
pre-bonded chips from suppliers, would likely constitute
good cause to supplement Anza’s infringement contentions
by adding claim 16 and the section 271(g) theory of in-
fringement.
     Setting aside Mushkin’s assertion that Anza’s infringe-
ment contentions waived claim 16 and the section 271(g)
theory of infringement, Mushkin’s arguments largely fall
away. The original complaint alleged infringement of
“each of the limitations of independent claims 1, 14, and 16
of the ’927 patent in violation of 35 U.S.C. § 271(a) and (g).”
Complaint at 8, Anza Tech., Inc. v. Mushkin, Inc., No. 1:17-
cv-03135-MEH (D. Colo. Mar. 28, 2017), ECF No. 75. Sim-
ilarly, the second amended complaint asserted infringe-
ment of “method of use” claims of the ’479 and ’864 patents
under 35 U.S.C. § 271(g). Second Amended Complaint at
17, 20, Anza Tech., Inc. v. Mushkin, Inc., No. 1:17-cv-03135-
MEH (D. Colo. June 8, 2018), ECF No. 75. Both complaints
therefore alleged infringement of “method of use” claims
under 35 U.S.C. § 271(g), such that the allegations of
ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.                    21



infringement in both the old and new claims would entail
activities conducted by upstream manufacturers. Accord-
ingly, there is a substantial overlap in the underlying facts
alleged in each of the complaints.
    Mushkin’s next argument is that the time frame when
infringement liability was allegedly incurred is signifi-
cantly different in the second amended complaint com-
pared to the original complaint. According to Mushkin, the
second amended complaint changed the relevant time pe-
riod from infringement that occurred within the six-year
period preceding March 2017 to infringement that occurred
between March 2011 and April 1, 2012. See Appellee Br.
38. But Mushkin fails to explain how the second time pe-
riod, which is wholly encompassed within the first, can be
regarded as distinctly different from the first. There is no
lack of notice and no substantial prejudice to Mushkin from
having to defend against independent claims over a shorter
period than the period set forth in the original complaint.
    At several points, Mushkin argues that Anza’s admis-
sion that the infringement allegations in the original com-
plaint were non-viable dooms its relation back argument.
Mushkin reasons that if the infringement claims in the sec-
ond amended complaint are similar enough to the infringe-
ment claims in the original complaint to relate back to the
date of the original complaint, the infringement claims in
the second amended complaint must also be non-viable. Al-
ternatively, Mushkin argues that if the current claims are
viable because they are not the same as the original ones,
the current claims should not relate back to the date of the
original complaint.
    That argument falls with its premise. Amended claims
do not have to be the same as the original claims to relate
back. Rather, the claims must arise out of the same con-
duct, transaction, or occurrence. In any event, the record
contains no explanation for the non-viability of the original
22                   ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.




claims, so there is no basis for concluding that Anza’s con-
cession that the original claims were non-viable means
that the claims in the second amended complaint must be
so different from the original claims that they cannot relate
back to the date of the original complaint.
    Mushkin further contends that applying the relation
back doctrine in this case would allow litigants to evade the
statute of limitations by bootstrapping old claims onto new
ones, thus rendering the statute of limitations a nullity. To
the contrary, while the relation back doctrine alters the
starting point for the statute of limitations, that starting
point can never be earlier than the filing date of the origi-
nal complaint. And in order for the relation back doctrine
to apply at all, the allegations of the amended complaint
must be tethered to the conduct, transactions, or occur-
rences underlying the original claims.
     Finally, Mushkin argues that “[w]ith the filing of the
Second Amended Complaint, two-thirds of the accused
products changed, including the addition of two new ac-
cused products.” That characterization of the change in the
set of accused products is misleading. In fact, the second
amended complaint omits ten of the original sixteen prod-
ucts from the list of accused products. The omission of
those products has no prejudicial effect on Mushkin and
does not deprive Mushkin of notice of any new allegations.
The other six products—Redline, Blackline, Radioactive,
Silverline, Proline, and Essentials—have been accused in
all three complaints. With regard to those six products, the
second amended complaint and the original complaint
would likely present closely related issues.
    The same, however, is not true for the two remaining
products, the Ridgeback and Apple products, which were
added for the first time in the second amendment com-
plaint. Courts that have addressed the issue of whether
newly alleged claims, based on separate patents, relate
ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.                     23



back to the date of the original complaint, have regarded
the presence of newly accused products as a substantial
factor weighing against the application of the relation back
doctrine. See PerfectVision, 951 F. Supp. 2d at 1093–94;
Halo Elecs., 2008 WL 1991094, at *3; see also Mann Design
Ltd. v. Bounce, Inc., 138 F. Supp. 2d 1174, 1179 (D. Minn.
2001) (finding no relation back, in part because “[t]here are
no allegations in the Complaint or the Amended Complaint
indicating that the products accused of infringing the ’061
patent are the same as those which allegedly infringe ei-
ther the ’559 and ’053 patent.”). The rationale for that rule
is that it is improbable that allegations regarding different
products, involving different patents, would have a com-
mon core of operative facts. It is therefore an open question
whether the allegations regarding the two newly accused
products, which are alleged to have infringed the latter two
patents, are too far afield from the original complaint to
put Mushkin on notice of the allegations against which it
would be required to defend.
    Resolution of that issue requires an analysis of facts
that are not before us and as to which the district court is
uniquely situated to rule. A remand for further proceed-
ings is therefore necessary so that the district court can de-
termine whether the infringement claims as to those two
products are sufficiently similar to the infringement claims
in the original complaint to justify application of the rela-
tion back doctrine to those products.
                             III
    We hold that the claims in the second amended com-
plaint that relate to the six originally accused products—
the Redline, Blackline, Radioactive, Silverline, Proline,
and Essentials products—relate back to the date of the
original complaint under Rule 15(c). For those products,
section 286 does not wholly bar an award of damages. The
grant of the motion to dismiss as to those products must
24                    ANZA TECHNOLOGY, INC. v. MUSHKIN, INC.




therefore be reversed. For the products that were added
for the first time in the second amended complaint—the
Ridgeback and Apple products—we vacate the order of dis-
missal and remand for the district court to determine,
based on a factual analysis in light of the legal standard set
forth above, whether the allegations regarding those prod-
ucts should relate back to the filing date of the original
complaint.
     REVERSED IN PART, VACATED IN PART, AND
                   REMANDED
