The Problems of the (Earlier) Plan 9 License

Note: This applies to the earlier license used for Plan 9. The current license of Plan 9 does qualify as free software (and also as open source). So this article's specific example is of historical relevance only. Nonetheless, the general point remains valid.

When I saw the announcement that the Plan 9 software had been released as “open source,” I wondered whether it might be free software as well. After studying the license, my conclusion was that it is not free; the license contains several restrictions that are totally unacceptable for the Free Software Movement. (See

I am not a supporter of the Open Source Movement, but I was glad when one of their leaders told me they don't consider the license acceptable either. When the developers of Plan 9 describe it as “open source,” they are altering the meaning of that term and thus spreading confusion. (The term “open source” is widely misunderstood; see

Here is a list of the problems that I found in the Plan 9 license. Some provisions restrict the Plan 9 software so that it is clearly nonfree; others are just extremely obnoxious.

First, here are the provisions that make the software nonfree.

You agree to provide the Original Contributor, at its request, with a copy of the complete Source Code version, Object Code version and related documentation for Modifications created or contributed to by You if used for any purpose.

This prohibits modifications for private use, denying the users a basic right.

and may, at Your option, include a reasonable charge for the cost of any media.

This seems to limit the price that may be charged for an initial distribution, prohibiting selling copies for a profit.

Distribution of Licensed Software to third parties pursuant to this grant shall be subject to the same terms and conditions as set forth in this Agreement,

This seems to say that when you redistribute you must insist on a contract with the recipients, just as Lucent demands when you download it.

1. The licenses and rights granted under this Agreement shall terminate automatically if (i) You fail to comply with all of the terms and conditions herein; or (ii) You initiate or participate in any intellectual property action against Original Contributor and/or another Contributor.

This seemed reasonable to me at first glance, but later I realized that it goes too far. A retaliation clause like this would be legitimate if it were limited to patents, but this one is not. It would mean that if Lucent or some other contributor violates the license of your GPL-covered free software package, and you try to enforce that license, you would lose the right to use the Plan 9 code.

You agree that, if you export or re-export the Licensed Software or any modifications to it, You are responsible for compliance with the United States Export Administration Regulations and hereby indemnify the Original Contributor and all other Contributors for any liability incurred as a result.

It is unacceptable for a license to require compliance with US export control regulations. Laws being what they are, these regulations apply in certain situations regardless of whether they are mentioned in a license; however, requiring them as a license condition can extend their reach to people and activities outside the US government's jurisdiction, and that is definitely wrong.

A part of the distribution is covered by a further unacceptable restriction:

2.2 No right is granted to Licensee to create derivative works of or to redistribute (other than with the Original Software or a derivative thereof) the screen imprinter fonts identified in subdirectory /lib/font/bit/lucida and printer fonts (Lucida Sans Unicode, Lucida Sans Italic, Lucida Sans Demibold, Lucida Typewriter, Lucida Sans Typewriter83), identified in subdirectory /sys/lib/postscript/font.

One part of this collection is free—the Ghostscript fonts that are covered by the GNU GPL. All the rest does not even come close.

Aside from those fatal flaws, the license has other obnoxious provisions:

…As such, if You or any Contributor include Licensed Software in a commercial offering (“Commercial Contributor”), such Commercial Contributor agrees to defend and indemnify Original Contributor and all other Contributors (collectively “Indemnified Contributors”)

Requiring indemnities from users is quite obnoxious.

Contributors shall have unrestricted, nonexclusive, worldwide, perpetual, royalty-free rights, to use, reproduce, modify, display, perform, sublicense and distribute Your Modifications, and to grant third parties the right to do so, including without limitation as a part of or with the Licensed Software;

This is a variant of the NPL asymmetry: you get limited rights to use their code, but they get unlimited rights to use your changes. While this does not by itself disqualify the license as a free software license (if the other problems were corrected), it is unfortunate.