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Protect Your Open-Source Project Before It's Too Late: A Legal Horror Story

Running a successful open-source project is one of the most rewarding experiences for a developer community. It’s also a journey full of unexpected challenges - some technical, some human, and, as we’ve recently learned, some legal.

This post is both an update on the status of the ExpressLRS project and a cautionary tale for other maintainers of widely adopted open-source software and hardware: if your project becomes popular, you must take legal steps early to protect its name and identity.

What Happened

Imagine spending years building an open-source project, only to find someone else trying to claim its name. On August 25th, 2025, we were notified that an individual, Christopher Henry Sauer (also known as “Christina Sauer”, “Chris Sauer”, radiomistress) had applied to register ExpressLRS as a trademark in China (Application No. 84786671).

On August 27th, 2025, this individual also registered the domain name expresslrs[.]dev.

On September 8th, 2025, we received further notification of another application from the same individual to register ExpressLRS as a trademark in the United States (Serial No. 99380841).

To be clear:

  • These are pending applications, not successful registrations.
  • Government trademark offices are currently reviewing the filings.
  • If the applications are preliminarily accepted, they will then be published for a formal opposition period, during which ExpressLRS LLC and others may contest them.

While this person once participated in community discussions, they were never part of the project team and are not associated with ExpressLRS in any official or unofficial capacity.

These filings were made without any involvement or authorization from ExpressLRS LLC or the ExpressLRS development team. If granted, they could limit how developers, contributors, and manufacturers use the ExpressLRS name - threatening the project’s open-source nature and causing confusion across the community. ExpressLRS LLC will formally oppose these applications to ensure the project’s identity remains protected.

Protecting ExpressLRS

In response, we have formed ExpressLRS LLC in the United States to represent the project’s interests and to hold our trademarks.

We are in the process of registering the ExpressLRS trademark in key regions around the world to protect the project and its community.

Every attempted registration made without authorization will be formally opposed by ExpressLRS LLC. We are committed to ensuring that the project’s name and identity remain in the hands of the community that built it.

On October 2nd, 2025, our legal counsel issued a cease-and-desist letter to the individual involved. The ExpressLRS developers are fully committed to protecting this project and the community that has supported it. We will not allow the trust, collaboration, and progress that make ExpressLRS possible to be undermined.

Why This Matters

The ExpressLRS project has grown far beyond what any of us imagined when it began. Developers and contributors have poured thousands of volunteer hours into creating the most capable open-source RC link available today. Manufacturers and vendors have invested in bringing ExpressLRS-based hardware to pilots around the world.

This work has always been driven by a spirit of openness and collaboration - not profit. It’s deeply discouraging that we must now divert energy and project funds to defend our community’s work from misappropriation, instead of focusing purely on improving the technology itself.

A Lesson for Other Open-Source Projects

If your project gains traction, it’s not enough to just write great code or design great hardware. Protect your project name early.

  • Register a trademark in key markets as soon as you can.
  • Form a legal entity to represent your community.
  • Don’t assume goodwill will be enough to protect you.

These steps may feel unnecessary when your project is just starting, but waiting until it becomes popular can leave it vulnerable.

If establishing your own legal entity isn't feasible, consider partnering with a fiscally sponsored Open Collective. OSC can register and manage trademarks on behalf of your project, providing legal protection without the need for direct incorporation. This service includes one hour of legal guidance and assistance with trademark registration and enforcement. For more details, visit OSC's Trademark & IP Guide.

How You Can Help

Securing trademarks and handling legal opposition is costly, and our team is handling this responsibly but with limited resources. If you believe in what we’re building and would like to support these efforts, monetary contributions can be made through our OpenCollective page, and other forms of support can be coordinated by contacting us at info@expresslrs.org.

Looking Forward

Despite this challenge, our mission hasn’t changed: to provide the world with the best open-source RC control system. We remain committed to transparency, collaboration, and innovation, and we’re grateful for the continued support of our incredible community.

Let this experience be a lesson for others in the open-source world: protect your projects early, so you can focus on building instead of defending.