Open source software in litigation: common legal pitfalls and how to avoid them

Open source software (OSS) is a cornerstone of modern development. From startups to enterprise giants, companies rely on open-source libraries, frameworks, and tools to build applications faster, reduce costs, and accelerate innovation. But with this convenience comes legal complexity—and when software disputes reach the courtroom, improper use of open-source code can create significant liabilities.

At Eureka Software, we’ve been brought into numerous litigation matters where the use of OSS became a key issue. Whether a company is accused of violating a license, misusing third-party code, or defending against infringement claims, understanding the legal landscape of open source is essential.

In this blog, we’ll explore the most common legal pitfalls associated with OSS in litigation and share practical guidance for businesses and developers to avoid them.

Why Open Source Matters in Legal Disputes

Open-source components are often integrated into proprietary software, but they come with specific licensing terms. If those terms are violated—intentionally or not—the company using the code can face:

Breach of contract claims

Regulatory investigations

Mandatory disclosure of proprietary source code

Loss of intellectual property protections

Most legal issues stem from a lack of awareness or compliance, rather than malicious intent. But in the eyes of the law, negligence can be just as damaging.

Common Legal Pitfalls in OSS Use

1. Ignoring License Terms

Every OSS package is governed by a license, and each license carries its own rules about use, modification, and distribution. Some allow commercial use with few restrictions; others require that any derivative work be made public under the same license.

Pitfall: A developer copies a library licensed under the GNU General Public License (GPL) into a proprietary product, unaware that the license requires the entire codebase to be open-sourced.

Legal Risk: Copyright violation, potential injunction, or forced release of proprietary code.

2. Assuming “Public” Means “Free to Use Without Conditions”

Just because code is posted on GitHub or Stack Overflow doesn’t mean it’s free of restrictions. Many developers mistakenly believe publicly available code is in the public domain.

Pitfall: A business integrates code from an online forum without verifying its origin or license.

Legal Risk: The original author—or the license holder—could later claim infringement or demand licensing fees.

3. Failing to Track and Document OSS Usage

Many companies have no idea how much open-source code is in their products, especially when developers download packages without formal approval or documentation. This becomes a serious problem during mergers, acquisitions, or litigation discovery.

Pitfall: A company undergoes a code audit and cannot account for open-source components embedded in its software.

Legal Risk: Legal uncertainty delays transactions, opens the door to licensing disputes, and undermines IP valuation.

4. Commingling Proprietary and Open Source Code

Blending proprietary code with certain types of open-source code—especially copyleft-licensed code—can create confusion about what parts of the software must be disclosed or redistributed.

Pitfall: A developer merges proprietary algorithms into a project governed by the Affero GPL (AGPL), which requires disclosure of any modifications.

Legal Risk: The company may be forced to make proprietary components public or face legal action from rights holders.

5. Failing to Address OSS in Employee Agreements and Training

Many developers use OSS as part of their day-to-day workflow. Without clear policies and training, employees may inadvertently introduce legal risk.

Pitfall: An employee adds code to a product from an open-source library with an incompatible license—and the company doesn’t find out until litigation arises.

Legal Risk: The company may be exposed to claims without having knowingly violated any rules.

How OSS Can Trigger Litigation

Open-source issues can come up in a wide range of legal contexts:

IP Infringement Claims: When plaintiffs claim their proprietary code was improperly derived from OSS or vice versa.

Contract Disputes: When licensing violations breach agreements with partners or customers.

Due Diligence Failures: When software audits during M&A uncover compliance gaps.

Trade Secret Misappropriation: When companies allege that OSS code was used to mask copied proprietary functionality.

In these scenarios, the stakes are high—and so is the need for detailed technical analysis.

How Eureka Software Supports OSS Litigation

At Eureka Software, we help attorneys, businesses, and courts navigate the complexities of open-source code in litigation. Our services include:

Source Code Analysis

We identify open-source components within proprietary products, evaluate licensing terms, and assess compliance.

License Compatibility Review

We analyze whether a company’s use of OSS complies with the license terms—and whether any conflicting licenses are present.

Development History Reconstruction

We trace how and when OSS was introduced into a project using commit logs, version control systems, and metadata.

Expert Witness Testimony

We present our findings clearly in court, translating technical details into understandable, persuasive arguments for legal teams, judges, and juries.

Our work has helped both plaintiffs and defendants clarify ownership, defend against infringement claims, and reach favorable resolutions in complex software disputes.

Best Practices to Avoid Open Source Legal Trouble

Businesses and development teams can reduce their risk exposure by implementing these proactive measures:

Use a Software Bill of Materials (SBOM): Track all OSS components, including transitive dependencies, and maintain documentation of licenses and sources.

Establish an Open Source Policy: Define what licenses are approved, who can approve new packages, and how OSS can be integrated into proprietary products.

Train Developers: Ensure your team understands the implications of different licenses and how to avoid accidental misuse.

Review Licensing Terms Carefully: Don’t rely on assumptions—read the actual license documentation or consult legal experts.

Perform Regular Audits: Periodically review your codebase to ensure ongoing compliance, especially before product launches, M&A, or public releases.

Open Source Is Powerful—But Comes With Responsibilities

Open-source software is a vital tool in modern development—but it’s not legally risk-free. When used carelessly, OSS can lead to copyright infringement claims, licensing violations, and even the loss of proprietary rights. When used wisely and with proper oversight, it can accelerate innovation and strengthen your software offerings.

At Eureka Software, we help businesses and legal teams handle open-source challenges with clarity and precision. Whether you need to understand the origins of your code, respond to a lawsuit, or prepare for an audit, our expert analysis ensures that your legal strategies are supported by credible, detailed technical insight.