Discrepancy between Apache-2.0 vs CERN-OHL-S-2.0 licensing on hardware files — legal risk

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Describe the problem you got

Summary

The README and root LICENSE state that the entire project is under Apache 2.0.

However, it appears the hardware repository (openarm_hardware) contains CAD/STL data that may actually be under CERN-OHL-S-2.0 (a more restrictive license). This discrepancy raises legal/compatibility concerns for downstream users, contributors, and integrators.

Why this matters

Users who rely on the Apache-2.0 declaration may assume they have broad rights (commercial use, modification, redistribution) for all components — but if parts of the hardware are under CERN OHL, those rights may be more limited or conditional.

License incompatibility may deter adoption, partnerships, or integration into other open hardware / robotics projects.

Worst case: it opens the project (or contributors) to legal risk from misunderstandings or claims from third parties or derivative users.

Evidence / Observations

The top‐level license file is Apache-2.0.

The hardware CAD repo (openarm_hardware) is CERN-OHL-S-2.0

Apache-2.0 and CERN-OHL-S-2.0 have different obligations (e.g. attribution, source distribution formats, etc.) which may conflict.

Suggested actions / questions

Clarify in documentation exactly which license(s) apply to each component (software, mechanical, CAD, firmware).

If the hardware/CAD files are indeed under CERN-OHL-S, please remove the "Fully Open Source" Statement which is false and misleading

Provide guidance on how derivative works combining both software and hardware can be licensed or redistributed in compliance with both licenses.

Consider re‐licensing hardware to something fully permissive if the goal is maximal openness (if feasible).

Optionally, seek counsel or community feedback about compatibility issues between Apache-2.0 and CERN OHL for hardware/software hybrid open projects.

[kou]

Clarify in documentation exactly which license(s) apply to each component (software, mechanical, CAD, firmware).

What is missing?

As you already correctly understood, hardware related resources are CERN-OHL-S-2.0 and others are Apache-2.0. It's mentioned explicitly:

• https://github.com/enactic/openarm_hardware?tab=readme-ov-file#license
• https://docs.openarm.dev/hardware/assembly-guide/find-cad-files/#-licensing

If the hardware/CAD files are indeed under CERN-OHL-S, please remove the "Fully Open Source" Statement which is false and misleading

CERN-OHL-S is an OSI approved license: https://opensource.org/license/cern-ohl-s

What do "false" and "misleading" mean?

Provide guidance on how derivative works combining both software and hardware can be licensed or redistributed in compliance with both licenses.

See the Apache-2.0 and CERN-OHL-S-2.0.

If you want to know more concrete example, could you clarify what situation are you interested in?

Consider re‐licensing hardware to something fully permissive if the goal is maximal openness (if feasible).

What does "openness" mean here?

FYI: I feel copyleft style OSS licenses are more "openness" than permissive style OSS licenses. Because all derivative works keep the original OSS licenses with copyleft style OSS licenses. Some derivative works may not keep OSS licenses with permissive style OSS licenses. I feel that OSS licensed derivative works are more "openness" than non OSS licensed derivative works.

Optionally, seek counsel or community feedback about compatibility issues between Apache-2.0 and CERN OHL for hardware/software hybrid open projects.

Could you clarify what situation are you interested in?

[kou]

#155 is a related issue.

[kou]

The README and root LICENSE state that the entire project is under Apache 2.0.

You refer https://github.com/enactic/openarm?tab=readme-ov-file#-license--conduct, right?

It doesn't mention "the entire project".

[SaneRelapse]

The README and root LICENSE state that the entire project is under Apache 2.0.

You refer https://github.com/enactic/openarm?tab=readme-ov-file#-license--conduct, right?

It doesn't mention "the entire project".

“Fully open source” in the colloquial sense usually means permissive licensing (MIT, BSD, Apache) — take it, use it, commercialize it, no real obligations beyond attribution. That’s the most innovation-friendly model.

“Copyleft open source” (GPL for software, CERN-OHL-S for hardware) is still open in the sense that source/designs are available and modifiable, but it comes with obligations: if you distribute modified versions, you must also publish your modifications under the same license. That makes it “open, but conditional.” Some see that as protective; others see it as restrictive.

So

A project cannot truthfully claim to be “fully open source” in the permissive Apache/MIT/BSD sense if parts are under copyleft.

It can say “open source software (Apache-2.0) + open hardware (CERN-OHL-S-2.0)” — but that’s very different from claiming it’s all Apache-2.0.

Saying “fully open source” without qualification is misleading because permissive and copyleft licensing philosophies are mutually exclusive in practice.
The website and Github state FULLY opensource, which is misleading
I appreciate your perspective KOU! huge respect for the work that has gone into OpenArm. The effort, dedication, and skill needed to create an open humanoid arm platform is clear, and I appreciate that this project has been shared with the community.

That said, I believe the reason why this repository has been receiving so many complaints is simply because the messaging is misleading if it wasn't people would not be complaining.
A change of statement is all that is needed.

A wise man once said: “Something can’t be both water and oil.”

[kou]

“Fully open source” in the colloquial sense usually means permissive licensing (MIT, BSD, Apache)

In general, you should not use your "open source" definition.

Open source (software) means that products (software) that released under OSI-approved licenses: https://opensource.org/licenses

https://opensource.org/faq#osd

What is “Open Source” software?

Generally, Open Source software is software that can be freely accessed, used, changed, and shared (in modified or unmodified form) by anyone. Open source software is made by many people, and distributed under licenses that comply with the Open Source Definition.

The internationally recognized Open Source Definition provides ten criteria that must be met for any software license, and the software distributed under that license, to be labeled “Open Source software.” Only software licensed under an OSI-approved Open Source license should be labeled “Open Source” software.

so many complaints

So many...?

BTW, what is your problem? You want to redistribute your fork under a proprietary license, right?

[kou]

Does #266 (preview: https://github.com/kou/openarm/tree/readme-add-license-to-repositories ) clarify our licenses?