Bardy Diagnostics, Inc. v. iRhythm Technologies, Inc.

IN THE UNITED STATES DISTRICT COURT
FOR THE DISTRICT OF DELAWARE
Case No. 1:24-cv-01355-JDW
MEMORANDUM
During litigation, there’s an advantage to fixing the pleadings as early as possible
so that everyone knows the issues in the case. But sometimes events outside of litigation
make that impossible. And sometimes, parties don’t know the facts upon which to base
their legal claims until they get discovery. This case prevents both issues. iRhythm
Technologies, Inc. asks for leave to assert infringement claims about two patents that
didn’t issue until September 2025. And Bardy Diagnostics, Inc., asks for leave to assert an
inequitable conduct defense for which it didn’t have a factual predicate until it gathered
information in discovery. Both requests are appropriate, and I will grant them both.
I. 	BACKGROUND
A. 	Factual History
Bardy filed this action in December 2024, asserting infringement of patents
directed to iRhythm’s wearable cardiac monitoring technology. iRhythm responded with
BARDY DIAGNOSTICS, INC.,
Plaintiff,
v.
IRHYTHM TECHNOLOGIES, INC.,
Defendant.
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counterclaims alleging that Bardy infringed iRhythm patents directed to Bardy’s invention,
the CAM patch. On April 4, 2025, I entered a Scheduling Order setting June 2, 2025, as the
deadline to amend pleadings. As the case progressed, both parties amended their
pleadings to add newly issued patents from related families. iRhythm ultimately asserted
five patents against Bardy, encompassing seventy-eight claims. Two of those patents, U.S.
Patent Nos. 12,274,554 and 12,303,277, issued in April and May 2025. Bardy did not assert
inequitable conduct defenses at that time.
In early September 2025, the United States Patent and Trademark Office issued
iRhythm two additional patents, U.S. Patent Nos. 12,402,819 and 12,408,856. Those
patents arise from the same patent families as the patents that iRhythm is asserting in this
case and concern the same accused product, the Bardy CAM patch. After the PTO
approved the claims, iRhythm notified Bardy of its intent to seek leave to amend its
counterclaims and provided Bardy with the claims. iRhythm also raised the issue with me
during a status conference in August 2025.
During the same period, Bardy pursued discovery relating to the prosecution of
the ’554 and ’277 patents. In September 2025, Bardy deposed Dr. David Schmidt, who
confirmed his substantive involvement in prosecuting those patents and his review of
materials relating 	to 	Japanese 	Patent 	Publication 	JP 	2004-121360, 	also 	known 	as
Matsumura, and an expert declaration by Jason Heikenfeld that no one disclosed to the
PTO during prosecution. Around the same time, iRhythm produced a privilege log
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identifying the role of its Director of Global Intellectual Property, Theodore Lopez, in
prosecuting the patents and approving claims for filing with the PTO. Bardy then sought
to depose Mr. Lopez, but iRhythm represented that it would produce him for deposition
only after inequitable conduct claims formally became part of the case.
In October 2025, the PTO ordered
ex parte reexamination of the ’554 and ’277
patents after finding that the full English translation of Matsumura raised a substantial
new question of patentability. Bardy served a proposed amended answer asserting
inequitable conduct defenses and counterclaims later that month.
B. 	Procedural History
On September 5, 2025, iRhythm moved for leave to amend its counterclaims to
assert the ’819 and ’856 patents. On January 5, 2026, Bardy moved for leave to amend its
answer to assert inequitable conduct defenses and counterclaims of unenforceability.
Claim construction briefing concluded on November 26, 2025, and I held a
Markman
hearing on January 15, 2026. Initial expert disclosures under Federal Rule of Civil
Procedure 26(a)(2) are due on May 15, 2026. Fact discovery remains open until July 17,
2026, and I have not set a trial date. Both motions are fully briefed and ripe for disposition.
II. 	LEGAL STANDARD
A. 	Rule 15
Federal Rule of Civil Procedure 15 governs the filing of both amended and
supplemental pleadings.
See Fed. R. Civ. P. 15(a), (d). Rule 15(a) contemplates amendment
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of an existing pleading and is intended “to enable a party to assert matters that were
overlooked or were unknown” when the original pleading was filed.
Garrett v. Wexford
Health, 938 F.3d 69, 82 (3d Cir. 2019) (quoting 6 Charles Alan Wright & Arthur Miller,
Federal Practice and Procedure § 1473 (3d ed. 2019)). By contrast, Rule 15(d) contemplates
a supplemental pleading that sets out “any transaction, occurrence, or event that
happened
after the date of the pleading to be supplemented.” Fed. R. Civ. P. 15(d)
(emphasis added);
see also Garrett, 938 F.3d at 82. The standard for granting leave under
both rules is essentially the same.
See 6 Wright & Miller, supra, § 1504 (citing
, inter alia,
Micron Tech., Inc. v. Rambus Inc., 409 F. Supp. 2d 552, 558 (D. Del. Jan. 13, 2006)).
“The decision to grant or deny leave to amend lies within the discretion of the
court.”
Compagnie des Grands Hotels d'Afrique SA v. Starwood Cap. Grp. Glob. I LLC, No.
CV 18-654-SB-SRF, 2021 WL 6883231, at *4 (D. Del. Feb. 10, 2021) (citations omitted).
Under Rule 15, courts should “freely give leave [to amend] when justice so requires.” Fed.
R. Civ. P. 15(a)(2). This liberal amendment regime helps effectuate the “general policy
embodied in the Federal Rules favoring resolution of cases on their merits.”
Mullin v.
Balicki, 875 F.3d 140, 149 (3d Cir. 2017). “Leave to amend must generally be granted
unless equitable considerations render it otherwise unjust.”
Arthur v. Maersk, Inc., 434 F.3d
196, 	204 	(3d 	Cir. 	2006). “Among 	the 	grounds 	that 	could 	justify 	a 	denial
of leave to amend are 	undue 	delay, 	bad 	faith, 	dilatory 	motive, 	prejudice, 	and
futility.”
Shane v. Fauver, 213 F.3d 113, 115 (3d Cir. 2000). An amendment is futile when it
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“fails to state a claim upon which relief can be granted, or advances a claim or defense
that is legally insufficient on its face.”
Cot'n Wash, Inc. v. Henkel Corp., 56 F. Supp.3d 613,
622 (D. Del. 2014) (cleaned-up);
Shane, 213 F.3d at 115. A “proposed amendment is not
futile [where it] would withstand a motion to dismiss.”
Free Speech Coal., Inc. v. Attorney
Gen. of U.S., 677 F.3d 519, 545 (3d Cir. 2012). “To survive a motion to dismiss, a complaint
must contain sufficient factual matter, accepted as true, to state a claim to relief that is
plausible on its face.”
Connelly v. Lane Const. Corp., 809 F.3d 780, 786 (3d Cir. 2016).
B. 	Rule 16
If a motion to amend satisfies Rule 15, but the motion comes after the deadline
that a scheduling order sets for amendments, the moving party must also satisfy Rule
16(b)(4) of the Federal Rules of Civil Procedure.
See E. Minerals & Chems. Co. v. Mahan,
225 F.3d 330, 340 (3d Cir. 2000). Rule 16(b)(4) provides that “[a] schedule maybe modified
only for good cause and with the judge's consent.” Fed. R. Civ. P. 16(b)(4). While Rule
15(a)(2) focuses on the question of prejudice to the non-moving party, Rule 16(b)(4)
“focuses on the moving party's burden to show due diligence.”
Race Tires Am., Inc. v.
Hoosier Racing Tire Corp., 614 F.3d 57, 84 (3d Cir. 2010);
see also WebXchange Inc. v. Dell
Inc., C.A. No. 08-132-JJF, 2010 WL 256547, at *2 (D. Del. Jan. 20, 2010). Thus, good cause
is established if the amendment is not unduly delayed, i.e., if the movant shows that it
acted diligently in filing its motion to amend. If the movant satisfies that requirement of
Rule 16, leave to amend should be granted unless there is a reason to deny leave, such as
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bad faith, prejudice to the non-moving party, or futility of the claims.
See Foman, 371 U.S.
at 182;
In re Burlington Coat Factory Sec. Litig., 114 F.3d 1410, 1434 (3d Cir. 1997).
III. 	ANALYSIS
A. 	iRhythm’s Motion
iRhythm seeks leave to amend its counterclaims to assert infringement of the ’819
and ’856 patents, which issued in early September 2025. Good cause exists to modify the
scheduling order to permit iRhythm to supplement its counterclaims. The ’819 and ’856
patents did not exist when the pleadings closed. iRhythm could not have asserted
infringement of issued patents before they issued, and iRhythm moved promptly once
issuance was imminent. Additionally, Bardy cannot claim surprise or lack of notice because
iRhythm provided Bardy advance notice of its intent to seek leave to amend its
counterclaims shortly after learning that the patents would issue. That notice is consistent
with diligence.
Bardy argues that iRhythm could have applies for these patents sooner. It does not
cite to any case, however, that finds a lack of diligence in applying for or prosecuting a
patent as a basis to deny leave to modify a scheduling order in court. And Bardy’s inability
to identify any such case is not surprising because its argument conflates patent
prosecution strategy with diligence. Rule 16 does not require a party to predict future
issuance of patents or to amend pleadings based on speculative future rights. Nor does
it impose rules about a party’s timing in applying for a patent. The relevant inquiry is
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whether the moving party acted reasonably once the basis for amendment existed.
iRhythm did, so I will amend the scheduling order to permit iRhythm’s amendment
request.
On the question of amendment, the governing rule is Rule 15(d), not Rule 15(a),
because the amended counterclaims purport to add patents that issued after the original
complaint and counterclaims were filed.
See Masimo Corp. v. Philips Electronics North
Am. Corp., Civ. No. 09–80, 2010 WL 1609899, *2–3 (D. Del. Apr. 20, 2010). Leave to
supplement 	is 	appropriate 	under 	Rule 	15(d) 	because 	the 	proposed 	supplemental
counterclaims arise from the same patent families as the patents that iRhythm is asserting,
share common specifications, and accuse the same Bardy product at issue in this case.
Courts in other districts have found that “there is substantial authority for allowing
supplemental 	pleadings 	where 	the new infringement 	claims 	relate 	to 	the 	same
technology 	or 	to new patents containing 	similar 	claims 	as 	those 	in 	the
original patent.”
See Lamoureux v. AnazaoHealth Corp., 669 F.Supp.2d 227, 237 n. 12
(D.Conn.2009) (collecting cases). Allowing supplementation will not unduly prejudice
Bardy, as the newly issued patents do not introduce a different accused product, a new
technology, or a materially different theory of infringement. In addition, any \additional
discovery 	will 	largely 	overlap 	with 	discovery 	already 	contemplated. 	Although
supplementation 	will 	require 	additional 	contentions 	and 	some 	incremental 	claim
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construction, that modest burden is not undue, particularly where iRhythm proposed a
measured schedule that integrates the new patents without displacing existing deadlines.
There is also no indication of bad faith or dilatory motive. iRhythm did not wait to
spring these new patents on Bardy. After the PTO approved the claims, iRhythm notified
Bardy of its intent to seek leave and provided copies of the claims. It raised the issue with
the Court at the August 2025 status conference and filed its Motion within days of the
’819 patent issuing. And when iRhythm filed its Motion, fact discovery remained open,
expert discovery had not begun, claim construction proceedings were underway but
incomplete, and no trial date had been set. Prejudice must be assessed as of that point in
time. Any increased difficulty resulting from the passage of time while the Motion was
pending cannot fairly be attributed to iRhythm and does not justify denial of leave.
Judicial 	economy 	further 	supports 	supplementation. 	Resolving 	infringement
disputes concerning closely related patents in a single action avoids duplicative discovery
and the risk of inconsistent rulings. Allowing the ’819 and ’856 patents to proceed in this
case will conserve judicial and party resources; the alternative would require the parties
to initiate a separate action involving the same technology and accused product.
B. 	Bardy’s Motion
“Inequitable conduct is an equitable defense to patent infringement that, if proved,
bars enforcement of a patent.”
Therasense, Inc. v. Becton, Dickinson & Co., 649 F.3d 1276,
1285 (Fed. Cir. 2011). A claim for inequitable conduct requires that (a) “the patentee acted
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with the specific intent to deceive” the PTO and (b) the material withheld from the PTO
satisfies “but-for materiality,” meaning the PTO would not have allowed a claim had it
known of the undisclosed material.
Therasense, 649 F.3d at 1290-91. A party claiming
inequitable conduct ordinarily must show that the patentee “withheld or misrepresented
information that, in the absence of the withholding or misrepresentation, would have
prevented a patent claim from issuing.”
Ohio Willow Wood Co. v. Alsp S., LLC, 735 F.3d
1333, 1345 (Fed. Cir. 2013).
Because Bardy seeks leave to amend its affirmative defenses to assert inequitable
conduct before the PTO, the heightened pleading standard of Federal Rule of Civil
Procedure 9(b) applies to its allegations. Rule 9(b) requires that “[i]n alleging fraud or
mistake, a party must state with particularity the circumstances constituting fraud or
mistake. Malice, intent, knowledge, and other conditions of a person’s mind may be
alleged generally.” “[I]nequitable conduct, while a broader concept than fraud, must be
pled with particularity” under Rule 9(b).
Exergen Corp. v. Wal-Mart Stores, Inc., 575 F.3d
1312, 1326 (Fed. Cir. 2009).
Good cause exists to modify the scheduling order to permit Bardy to seek to assert
its inequitable conduct defense because Bardy could not reasonably have met the
amendment deadline despite diligence. iRhythm asserted the ’554 and ’277 patents
shortly before and after that deadline, and Bardy did not yet possess the discovery
necessary to plead inequitable conduct with the particularity Rule 9(b) requires. Only after
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taking a key deposition and reviewing prosecution-related materials did Bardy have a
factual basis to seek to amend. That sequence demonstrates diligence, not delay. Courts
routinely find good cause under Rule 16 where, as here, a party waits to amend until
discovery supplies the facts necessary to satisfy Rule 9(b).
Enzo Life Sci., Inc. v. Digene
Corp., 270 F.Supp.2d 484, 487-89 (D. Del. Dec. 16, 2003).
iRhythm argues that Bardy knew the relevant references earlier and therefore
should have amended sooner. That argument overlooks the nature of inequitable conduct
pleading. Bardy needed to do more than identify prior art; it needed a factual basis to
allege knowledge, materiality, and intent by specific individuals. Bardy obtained that
information through discovery, after the amendment deadline.
Bardy’s proposed amended answer pleads inequitable conduct with sufficient
particularity to avoid futility. Bardy alleges that Mr. Lopez and Dr. Schmidt, both of whom
owed duties of candor, knew of the Heikenfeld Declaration and the English translation of
Matsumura during prosecution of the ’554 and ’277 patents, appreciated their relevance
to patentability, and chose not to disclose them. Bardy further alleges that those same
materials later prompted reexamination, reinforcing their materiality. Taken as true, those
allegations permit a reasonable inference of inequitable conduct that satisfies Rule 9(b).
At this stage, Bardy need not prove that inference or eliminate competing explanations.
Nor will amendment unduly prejudice iRhythm. The defenses concern only the ’554
and ’277 patents, which iRhythm added near the amendment deadline. Bardy gave
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advance notice of its intent to amend and shared a draft pleading before filing. The
relevant 	evidence, 	including 	prosecution 	history 	and 	the 	knowledge 	of 	iRhythm
personnel, lies largely within iRhythm’s control. Allowing amendment will not require the
parties to redo completed work or drastically disrupt the schedule.
IV. 	CONCLUSION
iRhythm has shown good cause to supplement its counterclaims, and its proposed
amendment satisfies Rule 15. Bardy has also shown good cause to amend its answer, and
its proposed inequitable conduct defenses and counterclaims are neither futile nor unduly
prejudicial. I will grant both motions for leave to amend. An appropriate Order follows.
BY THE COURT:
/s/ Joshua D. Wolson
JOSHUA D. WOLSON, J.
February 17, 2026
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