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How to prove software copyright infringement: a step-by-step legal & technical breakdown

Learn how to legally and technically prove software copyright infringement with this comprehensive step-by-step guide to protect your intellectual property.

Learn how to legally and technically prove software copyright infringement with this comprehensive step-by-step guide to protect your intellectual property.
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Software is one of the most valuable forms of intellectual property a business can own. Its originality, functionality, and performance often represent years of development and millions in investment. So, when a competitor or third party uses your code without permission, the damage is not only financial—it’s foundational.

But proving that your software was copied or misused isn’t as simple as showing two applications look or behave similarly. Software copyright infringement claims in legal proceedings require a detailed combination of legal argument and technical evidence.

At Eureka Software, we’ve supported dozens of copyright cases with deep forensic analysis, code comparisons, and clear, courtroom-ready expert testimony. In this blog, we’ll walk through what’s required to prove (or defend against) a software copyright infringement claim—from the legal framework to the technical tools used in expert analysis.

What Is Software Copyright Infringement?

Copyright protects the original expression of an idea, not the idea itself. In software, this means:

  • The specific source code or object code
  • The unique structure, sequence, and organization (SSO) of the code
  • Possibly elements of the user interface or documentation, if sufficiently original
  • A copyright holder must prove:

  • Ownership of a valid copyright.
  • The defendant copied protected elements of the work.
  • That the copying was substantial and unlawful.
  • Step-by-Step Breakdown: How to Prove Infringement

    1. Establish Copyright Ownership

    To begin, the plaintiff must show they own the copyrighted software. This may include:

  • Copyright registration with the U.S. Copyright Office
  • Employment or contractor agreements showing authorship
  • Documentation of development history and file creation
  • This step is foundational. Without a valid ownership claim, no infringement case can move forward.

    2. Access: Was the Software Available to the Alleged Infringer?

    Next, the plaintiff must show that the defendant had access to the copyrighted code. Common scenarios include:

  • Former employees or contractors now working for a competitor
  • Shared codebases, APIs, or repositories
  • Published but improperly reused open-source code with restrictive licenses
  • Even indirect access can be enough if there’s a reasonable opportunity to view or use the protected work.

    3. Prove Substantial Similarity

    This is the most technical—and often most contested—part of the case. Courts require proof that the two programs are substantially similar in ways that suggest copying, not coincidence or shared industry practices.

    At Eureka Software, our experts use a three-tiered approach:

    A. Literal Code Comparison

    We examine whether specific lines, functions, or files were copied, using forensic tools to:

  • Compare code syntax
  • Analyze comments and formatting
  • Track development timelines via version control logs
  • Even small blocks of code, if copied verbatim, can be enough to support infringement claims.

    B. Non-Literal Similarities

    We also analyze:

  • Overall architecture
  • Program flow
  • Data structures
  • Algorithms
  • Even if the literal code differs, copying may be shown if the structure and function are derived from the original.

    C. Filtering Out Unprotectable Elements

    Not all code is protectable. Our analysis filters out:

  • Open-source libraries
  • Functional elements dictated by external constraints
  • Common programming conventions (e.g., standard loops, API calls)
  • This ensures the court focuses on original, protectable expression rather than generic coding practices.

    4. Use Forensic Evidence to Strengthen the Case

    Forensic evidence can be key to proving access and copying in modern litigation. Our team often examines:

  • Timestamps and authorship logs
  • Commit histories in systems like Git
  • Deleted files or recovery data
  • Metadata showing file transfers or unauthorized downloads
  • We help show how and when code was copied—or establish that similarities stem from independent development.

    5. Expert Witness Testimony: Making the Technical Clear

    Even the most compelling technical evidence must be explained clearly to the court. Judges and juries often lack a software background, so they need help understanding what makes two programs similar, different, or potentially infringing.

    Eureka Software provides:

  • Concise expert reports
  • Side-by-side visualizations of code
  • Flowcharts or diagrams explaining program behavior
  • Objective, easy-to-understand testimony in court
  • Our role is to identify infringement and ensure the court understands the significance of our findings.

    Defending Against Infringement Claims

    On the other side of the courtroom, defendants can challenge infringement claims by showing:

  • The code was developed independently
  • The allegedly copied elements are unprotectable
  • The similarity is due to standard functionality or external constraints
  • In one case, a client was accused of copying an entire software module from a former partner. Our forensic investigation revealed that the overlapping functions were based on open-source standards and implemented differently. The court dismissed the case, saving our client from costly litigation.

    Evidence Matters — Let Eureka Software Help

    Proving software copyright infringement requires more than suspicion or surface-level similarities. It demands detailed technical analysis, a deep understanding of copyright law, and the ability to communicate complex findings to a legal audience.

    At Eureka Software, we specialize in this intersection. Our work supports both plaintiffs and defendants navigate the challenges of software copyright cases, providing the clarity, expertise, and courtroom experience needed to get to the truth.

    Contact us today to learn how we can support your copyright litigation with expert source code analysis, forensic review, and clear, defensible testimony.

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