What Are the Legal Considerations for Open Source Projects?
Open source projects carry real legal weight: the license you choose determines what others may legally do with your code, and the way you handle contributions, trademarks, and patents determines what rights you keep and what risks you take on. Open Source Guides addresses this directly in its "The Legal Side of Open Source" guide, which covers the questions maintainers most often wonder about — and a few they don't. The considerations below apply to anyone launching, maintaining, or contributing to a project; they are general explanations, not legal advice, and a lawyer should review anything high-stakes.
The license is the core legal decision
A license is the legal document that grants others permission to use, modify, and distribute your code. Without one, default copyright law applies: others have no legal right to copy, modify, or redistribute your work, even if it is publicly visible on a hosting platform.
Open Source Guides frames licensing as one of the first things to settle when starting a project. The practical questions to answer:
- Do you want to require that derivative works stay open? Copyleft licenses (such as GPL-family licenses) impose that condition; permissive licenses (such as MIT or Apache 2.0) generally do not.
- Do you care about patent grants? Some licenses include an explicit patent grant from contributors; others are silent on patents.
- Will your project be used in commercial or closed-source products? This affects which license a company's legal team will accept.
The guide's point is not that one license is correct, but that the choice should be deliberate and stated clearly in a LICENSE file at the root of the repository.
Copyright, contributions, and who owns what
You own the copyright to code you write. When someone else contributes, they own the copyright to their contribution unless they assign it to you or license it under the project's existing license.
This is why many projects use a Developer Certificate of Origin (DCO) or a Contributor License Agreement (CLA):
| Mechanism | What it does | Typical effect |
|---|---|---|
| DCO | Contributor signs off that they have the right to submit the code under the project license | Lightweight; keeps copyright with the contributor |
| CLA | Contributor grants the project (or a foundation) broader rights, sometimes including relicensing | Heavier; enables license changes and dual licensing |
If you ever want to change your project's license or offer it under different terms, the contribution paperwork you collected earlier determines whether that is possible. Deciding this at the start is far easier than reconstructing it later.
Patents and trademarks
Two areas maintainers often overlook:
- Patents. A license may or may not grant users a patent license covering the contributor's patents. If your project or your contributors hold relevant patents, the license text matters. Some licenses also include patent-retaliation clauses that terminate the grant if a user sues over patents.
- Trademarks. A license to code is not a license to your project's name or logo. Open Source Guides notes that trademarks are handled separately — you can permit code reuse while still controlling how the project's name is used, which protects users from confusing an unofficial fork with the original.
Practical steps to reduce legal risk
- Add a
LICENSEfile with the full text of your chosen license, and reference it in your README. - State contribution terms — a
CONTRIBUTING.mdthat explains whether you use a DCO sign-off or a CLA. - Keep a record of contributions through your version control history and any signed agreements.
- Handle dependencies deliberately — the licenses of libraries you depend on can impose obligations on your project.
- Adopt a code of conduct if you run a community; Open Source Guides treats this as part of healthy project governance, and it also has legal relevance for how you enforce participation rules.
- Document governance for larger projects, so decision-making authority (including over licensing) is clear.
Where to read further
Open Source Guides' "The Legal Side of Open Source" is the starting point on the site, alongside related guides on starting a project, maintainer best practices, leadership and governance, and getting paid for open source work. The site is itself open source and accepts contributions, so the material is maintained by the same community it describes. For a specific dispute, a licensing change, or a commercial agreement, consult a qualified lawyer — the guides explain the landscape, not your particular situation.