Home: Software Licenses
Open Source & Derivative Works
WordPress & the GPL
ProCD v. Zeidenberg
USL v. BSDi
Shrink Wrap License
MS Community License
MS Permissive License
Open Source software
is distributed under a variety of
licenses each of which usually
permits licensee to distribute and modify the software, provided that
the licensee complies with a specified set of terms and conditions.
A question that can therefore arise, is a licensee legally permitted
to create modifications
which combine elements of two (or more) different existing works into a single
work, and distribute the result?
The answer is that these types of combinations are generally only legally
permitted if the licensee can comply with all the pertinent
terms and conditions of all the licenses.
Additionally, it is worth noting that compatibility may only be in one
direction. For example:
- In some cases, one license agreement may contain terms and conditions which
can not simultaneously be satisfied with
the terms and conditions of another,
thus making compliance with all the terms and conditions impossible.
Such licenses are therefore said to be
It is therefore not legally permissible to combine and distribute
code which is under incompatible licenses - because you, as a licensee,
will always be in breach of at least one, and possibly more, of the licenses.
- In other cases, it may be possible to simultaneously comply with each
license agreement's terms and conditions. Such licenses are therefore said
to be "compatible".
It is therefore is legally permissible (assuming there are no other
legal reasons to stop you) to combine and distribute
code which is under compatible licenses - provided you, as a licensee,
comply with all the pertinent obligations in all of the licenses.
Finally, if you are the copyright holder of some code, it is should be possible
for you to place your own code under whichever license you want (even if you
have licensed it under a different license before - provided that was
done a non-exclusive basis) - thus allowing you a lot more flexibility as
to which other code you can combine with. Of course, you can not
relicense other people's code in this way - but if you are completely stuck,
you do have the option of approaching the author and asking them whether
they might consider
dual licensing their
- It is permissible to use software code which is
under some variants of the
BSD license in
GPL licensed project,
and then to distribute the result under
- It is not permissible to use software code which is
GPL license in
BSD licensed project,
and then to distribute the result under the
Discuss Compatible Licenses
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