GNU comments the BSD-2-clause license in: https://www.gnu.org/licenses/license-list.en.html#FreeBSD, referencing the comments on the BSD-3-clause license as all applying to the BSD-2-clause license.

They specifically state that the BSD licenses are prone to patent treachery.

I find the zlib/libpng license very similar to the BSD licenses. However, GNU doesn't claim the zlib to be prone to patent treachery. Do you know why?

1 Answer 1


In their license list, the FSF doesn't claim that the Zlib License is safe from “patent treachery”. The FSF makes no claim regarding this topic at all in that document.

The same patent issues apply to the whole permissive license family, including MIT/X11, BSD in their variants, and Zlib. As a guess, they only write a single sentence about the Zlib license because it is rarely used when compared with MIT or BSD licenses. They similarly don't mention this issue for the OpenLDAP license, Standard ML License, Unlicense, Vim license, Zope public license, … you get the point.

Licenses that explicitly discuss patent grants are for example the GPLv2 license family, GPLv3 license family, or the Apache 2 License.

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