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UNITED STATES DISTRICT COURT

FOR THE EASTERN DISTRICT OF TEXAS

MARSHALL DIVISION

HEADWATER RESEARCH LLC,

Plaintiff,

 v.

T-MOBILE USA, INC. and SPRINT

CORP.,

Defendants.

Civil Action No. 2:23-cv-00379-JRG-RSP

(Lead Case)

JURY DEMANDED

HEADWATER RESEARCH LLC,

Plaintiff,

 v.

T-MOBILE USA, INC. and SPRINT

CORP.,

Defendants.

Civil Action No. 2:23-cv-00377-JRG-RSP

(Member Case)

JURY DEMANDED

PLAINTIFF HEADWATER RESEARCH LLC’S UNOPPOSED MOTION FOR LEAVE 

TO AMEND INFRINGEMENT CONTENTIONS

Plaintiff Headwater Research LLC (“Headwater”) respectfully seeks leave, pursuant to 

P.R. 3-6(b), to amend its infringement contentions for good cause. Defendants T-Mobile USA, Inc. 

(“T-Mobile USA”) and Sprint Corp. (“Sprint”) (collectively, “T-Mobile” or “Defendants”) do not 

oppose this motion.

This is Headwater’s first request to amend its infringement contentions, and the proposed 

amendments do not change the scope of Headwater’s infringement allegations. Instead, the 

proposed amendments were prepared to address concerns raised by T-Mobile and were provided 

to T-Mobile on March 19, 2024, and the parties subsequently continued to confer about 

Headwater’s amendments and T-Mobile’s contemporaneous motion for leave to amend invalidity 

Case 2:23-cv-00379-JRG-RSP Document 56 Filed 04/15/24 Page 1 of 7 PageID #: 504
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contentions (filed as Dkt. No. 55). The parties do not oppose one another’s amendments. 

Headwater’s proposed amendments include essentially two changes. First, T-Mobile

requested that Headwater provide, for two of the asserted patents, a separate infringement chart 

for each group of accused products. For example, Headwater previously provided one chart for 

U.S. Patent No. 8,589,541 that encompassed mobile devices sold by T-Mobile, including devices 

manufactured by Samsung, Apple, Google, Motorola, and Nokia. In the proposed amended 

contentions, Headwater provides a separate chart for each such group (e.g., one chart for Samsung 

devices sold by T-Mobile, one chart for Apple devices sold by T-Mobile, etc.). This amendment 

does not change the scope of Headwater’s infringement contentions; it merely provides consistent 

citations for each device manufacturer.

As to the second change, T-Mobile expressed to Headwater its belief that Headwater’s 

original infringement contentions did not clearly accuse T-Mobile’s server-side functionality. 

Headwater disagreed but, after the parties met and conferred, agreed to amend its contentions to 

provide further clarity for the avoidance of doubt. In conjunction with this change, Headwater also 

added exemplary citations to certain confidential documents produced by T-Mobile several months 

after Headwater’s original contentions deadline.

Good cause exists for the proposed amendments, which were prepared in response to 

requests from T-Mobile. T-Mobile does not oppose the amendments.

ARGUMENT

A party may amend or supplement infringement contentions “by order of the Court, which

shall be entered only upon a showing of good cause.” P.R. 3-6(b). “Good cause...requires a

showing of diligence.” O2 Micro Int’l Ltd. v. Monolithic Power Sys., Inc., 467 F.3d 1355, 1366

(Fed. Cir. 2006). Courts apply the following four-factor test to determine whether good cause has

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been shown: (1) the explanation for the failure to meet the deadline; (2) potential prejudice in

allowing the thing that would be excluded; (3) the importance of the thing that would be excluded;

and (4) the availability of a continuance to cure such prejudice. Good cause exists here because all 

four factors weigh in favor of granting Headwater leave to amend.

A. Headwater acted diligently and in good faith

The proposed amendments originate from requests and feedback from T-Mobile. When TMobile questioned whether Headwater was accusing T-Mobile’s server-side functionality of 

infringement and requested that Headwater separate certain of its infringement contentions into 

additional charts, Headwater met and conferred with T-Mobile on February 22, 2024 and provided 

the proposed amendments to T-Mobile on March 19, 2024 to address T-Mobile’s concerns—which 

mirrored the types of amendments Headwater made to address similar concerns raised by 

defendant Verizon in Civil Action No. 2:23-cv-00352-JRG-RSP, who is represented by the same 

counsel as T-Mobile. After the February 22 meet-and-confer, the parties continued to confer 

regarding Headwater’s amended contentions and proposed amended invalidity contentions 

prepared by T-Mobile. Ultimately, the parties confirmed that they would not oppose one another’s 

amendments, with T-Mobile confirming this on April 8, 2024. Thus, Headwater acted diligently 

and in good faith to address T-Mobile’s concerns in the proposed amendments.

B. T-Mobile prompted the amendments and will not be prejudiced by them

T-Mobile does not oppose this motion and will not be prejudiced by the proposed 

amendments. The first change made by the proposed amendments (i.e., separating Headwater’s 

existing contentions into separate charts for each device manufacturer), the change does not change 

the scope of Headwater’s infringement contentions. It merely provides consistent citations for each 

device manufacturer in manufacturer-specific charts, and thus cannot be prejudicial. T-Mobile has 

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been aware of Headwater’s proposed amendments since at least March 19, 2024 when it was

provided copies of them. And T-Mobile was aware of the types of amendments Headwater would 

be making even before that time because its amendments mirrored those made to its contentions 

in Civil Action No. 2:23-cv-00352-JRG-RSP against defendant Verizon, who is represented by 

the same counsel as T-Mobile. In addition, the claim construction process is not scheduled to begin 

for another 2.5 months, and fact discovery is not scheduled to close for eight months, leaving 

ample time for T-Mobile to consider Headwater’s amended contentions. Dkt. No. 40; see Ax 

Wireless, LLC v. HP, Inc., No. 2:22-cv-0279-JRG-RSP, Dkt. No. 99, at *4-5 (E.D. Tex. Dec. 11, 

2023) (prejudice is minimal when amending contentions four months before the close of fact 

discovery). Thus, T-Mobile will not be prejudiced by the proposed amendments.

C. The proposed amendments are important, in light of T-Mobile’s feedback

Because the proposed amendments were prompted by T-Mobile, they are important. The 

first change made by the proposed amendments (i.e., separating Headwater’s existing contentions 

into separate charts for each device manufacturer) does not change the scope of Headwater’s 

contentions but was made at T-Mobile’s request because, presumably, the change was important 

to T-Mobile. The second change is also important because, although Headwater maintains that its 

original contentions sufficiently disclosed that T-Mobile’s server-side functionality is accused of 

infringement, T-Mobile believed that this was not sufficiently clear. It is important that the parties 

avoid any disagreement about the fundamental scope of this case, so Headwater’s proposed 

amendment is important in that it clarifies for the avoidance of doubt that T-Mobile’s server-side 

functionality is accused.

D. No continuance is necessary

No continuance is needed. Because the proposed amendments do not change the scope of 

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Headwater’s infringement theories and were prepared to address T-Mobile’s concerns, there is no 

prejudice and nothing to cure with a continuance. Where no continuance is sought, this factor 

weighs in favor of leave to amend. E.g., Arigna Tech. Ltd. v. Volkswagen AG, No. 2:21-CV-00054-

JRG-RSP, 2022 WL 2761288, at *3 (E.D. Tex. Jan. 19, 2022).

CONCLUSION

Accordingly, Plaintiff Headwater respectfully requests that the Court grant its Unopposed 

Motion for Leave to Amend Infringement Contentions.

Dated: April 15, 2024 Respectfully submitted,

/s/ Marc Fenster

Marc Fenster

CA State Bar No. 181067

Email: mfenster@raklaw.com

Reza Mirzaie

CA State Bar No. 246953

Email: rmirzaie@raklaw.com

Brian Ledahl

CA State Bar No. 186579

Email: bledahl@raklaw.com

Ben Wang

CA State Bar No. 228712

Email: bwang@raklaw.com

Adam Hoffman

CA State Bar No. 218740

Email: ahoffman@raklaw.com

Paul Kroeger

CA State Bar No. 229074

Email: pkroeger@raklaw.com

Neil A. Rubin

CA State Bar No. 250761

Email: nrubin@raklaw.com

Kristopher Davis

CA State Bar No. 329627

Email: kdavis@raklaw.com

James S. Tsuei

CA State Bar No. 285530

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Email: jtsuei@raklaw.com

Philip Wang

CA State Bar No. 262239

Email: pwang@raklaw.com

Amy Hayden

CA State Bar No. 287026

Email: ahayden@raklaw.com

James Milkey

CA State Bar No. 281283

Email: jmilkey@raklaw.com

Qi Peter Tong

TX State Bar No. 24119042

Email: ptong@raklaw.com

Jason M. Wietholter

CA State Bar No. 337139

Email: jwietholter@raklaw.com

RUSS AUGUST & KABAT

12424 Wilshire Blvd. 12th Floor

Los Angeles, CA 90025

Telephone: 310-826-7474

ATTORNEYS FOR PLAINTIFF,

Headwater Research LLC

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CERTIFICATE OF SERVICE

The undersigned certifies that on April 15, 2024, all counsel of record who are deemed to 

have consented to electronic service are being served with a copy of this document via electronic 

mail.

/s/ Marc Fenster

Marc Fenster

CERTIFICATE OF CONFERENCE

The undersigned certifies that on February 22, 2024, counsel for all parties met and 

conferred in accordance with L.R. CV-7(h). This motion is unopposed.

/s/ Marc Fenster

Marc Fenster

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