PUBLISHED

UNITED STATES COURT OF APPEALS FOR THE FOURTH CIRCUIT

No. 22-1812

SYNOPSYS, INC.,

Plaintiff – Appellee,

v.

RISK BASED SECURITY, INC.,

Defendant – Appellant.

Appeal from the United States District Court for the Eastern District of Virginia, at Richmond. John A. Gibney, Jr., Senior District Judge. (3:21-cv-00252-JAG)

Argued: March 8, 2023 Decided: June 15, 2023

Before AGEE and RUSHING, Circuit Judges, and Joseph DAWSON III, United States District Judge for the District of South Carolina, sitting by designation.

Affirmed by published opinion. Judge Agee wrote the opinion, in which Judge Rushing and Judge Dawson joined.

ARGUED: Andrew Evan Samuels, BAKER & HOSTETLER LLP, Columbus, Ohio, for Appellant. Catherine Emily Stetson, HOGAN LOVELLS US LLP, Washington, D.C., for Appellee. ON BRIEF: Kevin W. Kirsch, Columbus, Ohio, Michael S. Gordon, New York, New York, Christopher A. Wiech, BAKER & HOSTETLER LLP, Atlanta, Georgia; C. Dewayne Lonas, Stewart R. Pollock, MORAN REEVES CONN PC, Richmond, Virginia, for Appellant. N. Thomas Connally, Christopher T. Pickens, Tysons, Virginia, USCA4 Appeal: 22-1812 Doc: 65 Filed: 06/15/2023 Pg: 2 of 31

Patrick T. Michael, San Francisco, California, Sean Marotta, Johannah Walker, HOGAN LOVELLS US LLP, Washington, D.C., for Appellee.

2 USCA4 Appeal: 22-1812 Doc: 65 Filed: 06/15/2023 Pg: 3 of 31

AGEE, Circuit Judge:

Both Risk Based Security, Inc. (“RBS”) and Synopsys, Inc., identify vulnerabilities

in the source code of software and share information about those vulnerabilities so they

can be corrected before nefarious individuals exploit them. After RBS accused Synopsys

of engaging in unlawful conduct related to the content of RBS’ vulnerability database,

Synopsys filed this declaratory judgment action. In relevant part, Synopsys sought a

judicial declaration that it had not misappropriated RBS’ trade secrets. On the merits, the

district court granted Synopsys’ motion for summary judgment on that claim after

concluding that RBS had not come forward with evidence showing that any of its alleged

trade secrets satisfied the statutory definition of that term. RBS appeals by challenging the

district court’s merits determination of trade secrets as well as its decisions denying RBS’

motion to dismiss the case as moot, excluding testimony from two of RBS’ expert

witnesses, and denying its motion for partial summary judgment as to some of its trade

secret claims. For the reasons set out below, we affirm the district court’s judgment in favor

of Synopsys.

I.

Software programs run according to their list of instructions, and those instructions

are found in the programs’ code. See Decision Insights, Inc. v. Sentia Grp., Inc., 416 F.

App’x 324, 325 n.2 (4th Cir. 2011) (per curiam)) (describing “source code” as “a document

written in computer language, which contains a set of instructions designed to be used in a

computer to bring about a certain result” (citing Trandes Corp. v. Guy F. Atkinson Co., 996

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F.2d 655, 662–63 (4th Cir. 1993))). Many software programs use open source code,

meaning that the code is publicly accessible. Open source code allows fo

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