Opinion

IN THE UNITED STATES DISTRICT COURT

FOR THE NORTHERN DISTRICT OF TEXAS

DALLAS DIVISION

DURAPLAS, LP, §

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Plaintiff-Counterclaim Defendant, §

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v. § Civil Action No. 3:25-CV-1310-K

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DIVERSITECH CORPORATION, §

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Defendant-Counterclaim Plaintiff. §

MEMORANDUM OPINION AND ORDER

Before the Court are DiversiTech Corporation’s Motion for a Preliminary

Injunction (Doc. No. 64) (“Motion for Preliminary Injunction”), DiversiTech

Corporation’s Brief in Support of its Motion for Preliminary Injunction (Doc. Nos. 65

(public version) & 69 (sealed version)) (“Brief in Support of Motion for Preliminary

Injunction”), Plaintiff DuraPlas, LP’s Response in Opposition to Defendant’s Motion

for Preliminary Injunction and Brief in Support (Doc. Nos. 84 (public version) & 87

(sealed version)) (“Opposition to Preliminary Injunction”), DiversiTech Corporation’s

Reply Brief in Further Support of its Motion for Preliminary Injunction (Doc. No. 99)

(“Reply in Support of Preliminary Injunction”), and the supporting appendices. The

Court has carefully considered the Motion for Preliminary Injunction, the Brief in

Support of Motion for Preliminary Injunction, the Opposition to Preliminary

Injunction, and the Reply in Support of Preliminary Injunction, as well as the

applicable law and the supporting appendices. For the reasons stated below, the

Court DENIES the Motion for Preliminary Injunction.

Also before the Court are Plaintiff DuraPlas, LP’s Motion to Strike Defendants’

Improper Reply and Supporting Evidence or, in the Alternative, for Leave to File a Sur-

Reply and Brief in Support (“Motion to Strike”) (Doc. No. 101), DiversiTech’s

Response in Opposition to DuraPlas’s Motion to Strike Portions of Reply in Support

of Preliminary Injunction (Doc. No. 118) (“Response to Motion to Strike”), and

Plaintiff DuraPlas, LP’s Reply in Support of Its Motion to Strike (Doc. No. 136)

(“Reply in Support of Motion to Strike”). The Court has carefully considered the

Motion to Strike, the Response to Motion to Strike, and the Reply in Support of

Motion to Strike, as well as the applicable law. For the reasons stated below, the

Court GRANTS IN PART AND DENIES IN PART the Motion to Strike.

I. Background

In this case, DiversiTech Corporation (“DiversiTech”) alleges DuraPlas, LP

(“DuraPlas”) infringes U.S. Patent No. 12,312,123 (the “’123 Patent”) along with

other patents. In the Motion for Preliminary Injunction, DiversiTech moves pursuant

to Federal Rule of Civil Procedure 65(a) and 35 U.S.C. § 283 for a preliminary

injunction based on its positions that DuraPlas’s PolarPad products likely infringe

Claims 1, 4–7, and/or 9 of the ’123 Patent, that the ’123 Patent is likely valid, that

DiversiTech has suffered and will continue to suffer irreparable harm from DuraPlas’s

infringement absent a preliminary injunction, and that the balance of equities and

public interest favor a preliminary injunction.

In the Motion to Strike, DuraPlas moves to strike Section I of DiversiTech’s

Reply in Support of Preliminary Injunction as well as the appendix attached to that

brief based on its positions that DiversiTech improperly made new arguments for the

first time in that brief and improperly attached over 200 pages of new evidence in the

appendix attached to that brief. In the alternative, DuraPlas requests permission to file

a sur-reply addressing the alleged new arguments and evidence.

II. Standard of Review

A preliminary injunction is an extraordinary remedy. Winter v. Nat. Res. Def.

Council, Inc., 555 U.S. 7, 24 (2008). A party seeking a preliminary injunction must

establish a likelihood of success on the merits, a likelihood of irreparable harm in the

absence of preliminary relief, that the balance of equities tips in its favor, and that an

injunction is in the public interest. Id. In the context of alleged patent infringement, a

patentee’s entitlement to a preliminary injunction is a matter largely within the

discretion of the trial court. Titan Tire Corp. v. Case New Holland, Inc., 566 F.3d 1372,

1375 (Fed. Cir. 2009).

“[W]hen a party raises new arguments or evidence for the first time in a reply,

the district court must either give the other party an opportunity to respond or decline

to rely on the new arguments and evidence.” Georgia Firefighters’ Pension Fund v. Anadarko

Petroleum Corp., 99 F.4th 770, 774 (5th Cir. 2024).

III. Analysis

DiversiTech has not met its burden of establishing entitlement to the

extraordinary remedy of a preliminary injunction. In particular, even considering the

Reply in Support of Preliminary Injunction, DuraPlas has raised a substantial invalidity

defense. Furthermore, DiversiTech’s six-month delay in filing its motion undermines

its position that there is irreparable harm in the absence of a preliminary injunction.

But the Court also declines to rely upon the numerous arguments and extensive

evidence (including two expert declarations) DiversiTech waited to provide until filing

its Reply in Support of Preliminary Injunction. Critically, at the time it filed its Motion

for Preliminary Injunction, DiversiTech already had received DuraPlas’s invalidity

contentions. DiversiTech has no valid excuse for waiting until its Reply in Support of

Preliminary Injunction to make its arguments and present its evidence related to

validity and, in particular, to demonstrate why DuraPlas’s invalidity positions did not

bar it from entitlement to a preliminary injunction. This strategic decision prompted

the Motion to Strike, delayed final briefing related to the evidence underlying the

Motion for Preliminary Injunction, and evidences a lack of diligence in presenting

arguments and evidence in favor of a preliminary injunction, further undermining its

position that there is irreparable harm in the absence of a preliminary injunction.

Finally, DiversiTech fails to establish the existence of a substantial threat of irreparable

harm that will likely result absent injunctive relief given that DuraPlas has ceased

manufacturing and selling the relevant version of the PolarPad.

A. Likelihood of Success

As for the first element related to the Motion for Preliminary Injunction,

likelihood of success on the merits, in this context the patentee must show that it will

likely prove infringement and likely withstand any challenges to the validity of its

patent. Titan Tire Corp., 566 F.3d at 1376. At this stage, moreover, the accused infringer

need not make out a case of actual invalidity to avoid a preliminary injunction, but

need only show a substantial question of invalidity. FMC Corp. v. Sharda USA, LLC,

145 F.4th 1326, 1334 (Fed. Cir. 2025). If challenged, the patent owner must show it

is more likely than not to prevail over an invalidity challenge. Id.

Here, DiversiTech has not established a likelihood of success on the merits

because DuraPlas has raised substantial questions that the relevant claims of the ’123

Patent may be invalid. In its Brief in Support of Preliminary Injunction, DiversiTech

simply asserted “DuraPlas is unlikely to establish a substantial question as to the

validity” of the ’123 Patent, highlighted that the “presumption of validity applies,” and

argued “DuraPlas has raised no genuine basis to question the validity of the issued

patent.” Doc. No. 65 at 16–17 (all citations to CM/ECF page number unless otherwise

noted). That’s it. DiversiTech did not address any invalidity position that DuraPlas

had already disclosed to DiversiTech in DuraPlas’s invalidity contentions.

Were the Motion for Preliminary Injunction and Brief in Support of Preliminary

Injunction filed early in this case, particularly before invalidity contentions were served,

it might make sense that those documents do not provide any details explaining why

asserted patent claims are not invalid. But at the time DiversiTech filed its Motion for

Preliminary Injunction, it had already received DuraPlas’s invalidity contentions.

Even a cursory review of the Declaration of David Smith in Support of

DiversiTech Corporation’s Reply Brief for Preliminary Injunction (Doc. No. 100-4)

reveals numerous citations and extensive discussion of DuraPlas’s invalidity

contentions. Likewise, the Declaration of Andrew H. Hirshfeld in Support of

DiversiTech Corporation’s Reply Brief for Preliminary Injunction (Doc. No. 100-1)

includes several citations and discussion of DuraPlas’s invalidity contentions. There is

no good excuse for waiting until the reply to present these declarations.

DiversiTech attempts to explain away its decision to wait. It highlights how the

Federal Circuit once indicated in a footnote that “[i]nvalidity is an affirmative defense,

and the patentee need not address invalidity as an initial matter in filing for a

preliminary injunction.” Gaymar Indus., Inc. v. Cincinnati Sub-Zero Prods., Inc., 790 F.3d

1369, 1375 n.7 (Fed. Cir. 2015). Had DiversiTech filed its Motion for Preliminary

Injunction earlier in the case before it received any invalidity contentions,

DiversiTech’s invocation of this Federal Circuit statement would ring true. But in

Gaymar the Federal Circuit was not addressing whether a motion for a preliminary

injunction should address already-disclosed invalidity positions, the issue here.

Furthermore, in Gaymar the Federal Circuit highlighted how there was “a dispute

between the parties as to whether Gaymar had the burden of addressing validity in its

preliminary injunction (to show likelihood of success) or whether Gaymar was obligated to

address the issue only after CSZ raised the issue.” Id. at 1375 (emphasis added). Here, there

is no question DuraPlas raised invalidity issues in its invalidity contentions, and there

is no question DiversiTech failed to address those issues in its Motion for Preliminary

Injunction or Brief in Support of Preliminary Injunction. In other words, Gaymar does

not address comparable facts.

In short, there is no excuse permitting DiversiTech to sandbag DuraPlas in the

briefing related to the Motion for Preliminary Injunction. See, e.g., BHI Energy I Power

Servs., LLC v. KVP Energy Servs., LLC, No. 3:22-CV-1981-L, 2023 WL 223179, at *3

(N.D. Tex. Jan. 17, 2023) (Lindsay, J.) (“The sheer volume of materials submitted by

Plaintiff for the first time in support of its reply brief is akin to an unfair ambush, and

Plaintiff has yet to explain why it was unable to seek leave or submit the evidence when

it filed its Motion for Preliminary Injunction.”). Given that DiversiTech failed to

address disclosed invalidity positions in its opening brief and waited until its reply to

present arguments and evidence related to those disclosed invalidity positions, the

Court declines to rely on the new arguments and evidence submitted by DiversiTech

in its reply brief and associated appendix. See id. (declining to rely on materials

submitted with reply brief).

But even if the Court considered all of the Reply in Support of Preliminary

Injunction, the Court would still deny the Motion for Preliminary Injunction. In

particular, like the Brief in Support of Preliminary Injunction, the Reply in Support of

Preliminary Injunction does not address the invalidity arguments related to the Hef-T-

Pad prior art submitted by DuraPlas not only in its invalidity contentions but in its

Opposition to Preliminary Injunction.

In particular, in its Opposition to Preliminary Injunction, DuraPlas argued and

presented evidence from its invalidity contentions that “the Hef-T-Pad prior art raises

a substantial question of validity because it discloses every limitation of the asserted

claims, either alone or in view of other prior art.” Opposition to Preliminary Injunction

at 14; Exhibit H (Doc. 85-24). In its Reply in Support of Preliminary Injunction,

DiversiTech makes three arguments related to validity. But none meets its burden to

show it is more likely than not to prevail over this invalidity challenge.

First, DiversiTech says, “during prosecution of a related application . . .

DiversiTech disclosed the very Hef-T-Pad images and invalidity claim charts that

DuraPlas contends should have been disclosed and the examiner nonetheless allowed”

the related application to issue as another patent. Doc. No. 99 at 8–9. But the fact that

a patent examiner allowed different claims to issue over the Hef-T-Pad prior art does

not address whether the asserted claims of the ’123 Patent are invalid in light of the

Hef-T-Pad prior art.

Second, DiversiTech continues, “DuraPlas has failed to offer competent

evidence that the prior art it identifies renders the ’123 Patent anticipated or obvious.”

Id. at 9. In particular, DiversiTech criticizes DuraPlas for failing to provide a definition

of a person of ordinary skill in the art and for failing to offer expert testimony. But, in

both respects, DiversiTech has not cited any controlling authority requiring a definition

of a person of ordinary skill in the art or expert testimony in response to a motion for

a preliminary injunction. And, contrary to DiversiTech’s position, the Federal Circuit

has held that “[v]alidity challenges during preliminary injunction proceedings can be

successful, that is, they may raise substantial questions of invalidity, on evidence that

would not suffice to support a judgment of invalidity at trial.” Amazon.com, Inc. v.

Barnesandnoble.com, Inc., 239 F.3d 1343, 1358 (Fed. Cir. 2001). Moreover, again

contrary to DiversiTech’s position, the Federal Circuit has held that, “[g]enerally,

expert testimony is not required at the preliminary injunction stage given the lower

burden and because the timing of a preliminary injunction may foreclose the possibility

of developing ‘a fully comprehensive presentation of [an accused infringer’s] defenses.’”

BlephEx, LLC v. Myco Indus., Inc., 24 F.4th 1391, 1403 (Fed. Cir. 2022) (quoting New

England Braiding Co. v. A.W. Chesterton Co., 970 F.2d 878, 883 (Fed. Cir. 1992)).

Third, DiversiTech concludes, “none of the prior art [DuraPlas] identifies

anticipates or makes obvious the claims at issue.” Doc. No. 99 at 11. But in making

this argument, DiversiTech never addresses the Hef-T-Pad prior art. DiversiTech

instead addresses “Adam,” “Jones,” “Apps,” “Maldonado Cortés,” and “Dysinger.” Id.

at 11–12.

In short, DiversiTech has not shown it is more likely than not to prevail over

DuraPlas’s invalidity challenge. In particular, DiversiTech never provides any

indication in its Reply in Support of Preliminary Injunction, let alone in its Brief in

Support of Preliminary Injunction, of why the Hef-T-Pad prior art does not anticipate

or render obvious the asserted claims of the ’123 Patent, as demonstrated by DuraPlas

in its invalidity contentions and Opposition to Preliminary Injunction.

B. Likelihood of Irreparable Harm

As for the second element related to the Motion for Preliminary Injunction,

irreparable harm in the absence of a preliminary injunction, delay in seeking

preliminary relief is an important factor bearing on the need for a preliminary

injunction. High Tech Med. Instrumentation, Inc. v. New Image Indus., Inc., 49 F.3d 1551,

1557 (Fed. Cir. 1995). Absent a good explanation, a substantial period of delay

demonstrates there is no apparent urgency to the request for injunctive relief. Id.

Here, DiversiTech waited to seek a preliminary injunction for over six months

after DuraPlas filed its original complaint including declaratory judgment claims related

to the ’123 Patent. See Plaintiff’s Original Complaint (Doc. 1) (dated May 26, 2025);

Motion for Preliminary Injunction (Doc. 64) (dated Dec. 12, 2025). Judge Lindsay

found a comparable six-month delay in seeking a preliminary injunction after a lawsuit

was filed to be “sufficient to rebut any possible presumption of irreparable harm.”

Gonannies, Inc. v. Goupair.Com, Inc., 464 F. Supp. 2d 603, 609 (N.D. Tex. 2006)

(Lindsay, J.) (six-month delay in seeking preliminary injunction after lawsuit filed). The

six-month delay here, at a minimum, undercuts DiversiTech’s argument that it is likely

to establish irreparable harm in the absence of a preliminary injunction.

But, even if the period of delay before filing the Motion for Preliminary

Injunction were not enough, standing alone, to demonstrate the absence of irreparable

harm, DiversiTech’s failure to include all of the relevant evidence in the original

appendix attached to its Motion for Preliminary Injunction—as discussed above after

DiversiTech had already received DuraPlas’s invalidity contentions—served only to

prompt the Motion to Strike and create additional delay. In short, DiversiTech’s delay

in filing the Motion for Preliminary Injunction combined with its failure to submit

arguments and evidence with that motion in light of disclosed invalidity positions

evidence a lack of urgency.

Finally, the Court notes the same facts identified in its Order (Doc. 154) denying

DiversiTech’s separate motion for a temporary restraining order and preliminary

injunction related to alleged infringement of U.S. Patent No. 12,522,399. In particular,

DuraPlas states that it “has permanently ceased manufacturing and selling Version 1

[PolarPads],” “[a]ll remaining Version 1 [PolarPads] in DuraPlas’s possession have

been removed from inventory[,]” and “DuraPlas has also removed the Version 1 molds

from its manufacturing facility and transitioned its website and social media accounts

to promote only Version 2 pads.” Doc. No. 137 at 21–22. Based on these facts, and

the fact that the present Motion relates only to Version 1 PolarPads (Doc. No. 99 at

24 (requesting injunctive relief only related to “Version 1 condenser pads”)), the Court

also finds here that DiversiTech fails to establish the existence of a substantial threat

of irreparable harm that will likely result absent injunctive relief. See Winter, 555 U.S.

at 22. Specifically, DiversiTech again fails to establish that the alleged harm “cannot

be undone through monetary remedies.” Dennis Melancon, Inc. v. City of New Orleans,

703 F.3d 262, 279 (5th Cir. 2012) (internal quotations omitted). Further, DiversiTech

fails to establish the imminent threat of irreparable harm required for injunctive relief

to issue. See ADT, LLC v. Cap. Connect, Inc., 145 F. Supp. 3d 671, 694 (N.D. Tex. 2015)

(Fish, C.J.) (emphasis added); Mannatech, Inc. v. Wellness Quest, LLC, No. 3:14-CV-

2497-K, 2014 WL 11515729, at *1 (N.D. Tex. Nov. 4, 2014) (Kinkeade, J.).

Accordingly, DiversiTech fails to establish all four elements required to obtain

injunctive relief. See Speed v. Am.’s Wholesale Lender, No. 3:14-CV-3425-L, 2014 WL

4755485, at *1 (N.D. Tex. Sept. 24, 2014) (Lindsay, J.) (noting that, “if a party fails

to meet any of the four requirements, the court cannot grant a [temporary restraining

order] or preliminary injunction”).

IV. Conclusion

For the reasons stated above, the Court hereby DENIES the Motion for

Preliminary Injunction. As set forth above, DiversiTech has not met its burden to

demonstrate a substantial likelihood of success on the merits and, alternatively, has

failed to demonstrate a likelihood of irreparable harm in the absence of a preliminary

injunction. Also, for the reasons stated above, the Court hereby GRANTS IN PART

the Motion to Strike to the extent it requests the Court strike the appendix filed with

the Reply in Support of Preliminary Injunction and the new arguments in Section I of

the Reply in Support of Preliminary Injunction, including arguments that rely upon

the appendix filed with the Reply in Support of Preliminary Injunction. The Court

hereby DENIES IN PART the Motion to Strike to the extent it requests permission

to file a sur-reply brief in opposition to the Motion for Preliminary Injunction. The

Court also hereby DENIES DiversiTech’s request for retroactive leave to file its reply

appendix.

SO ORDERED.

Signed July 20", 2026.

ED KINKEADE

UNITED STATES DISTRICT JUDGE

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