Licensing a python module

Cinly Ooi cinly.ooi at
Thu Apr 24 09:39:33 UTC 2008

On 24/04/2008, Matthew Flaschen <matthew.flaschen at> wrote:
> Dan Stromberg wrote:
> > I'd like to use it in a program I'm writing for my employer, and they
> > seem cautious about the GPL.  If a program I write on my employer's time
> > uses a python module that is GPL, does that mean the program must also be
> > GPL?
> >
> If you work as a programmer/software engineer/reasonably related
> profession, it's quite possible that the module already belongs to your
> employer.  It might even if your occupation were unrelated to software.
>  This would all depend on your employment contract and your jurisdiction.

First thing first, IANAL.

The copyright is usually, by default, owned by your employer. GPL's
provision does not kick in unless you distribute it, i.e., give the module
to a third party. With GPL, there is no transfer of copyright, i.e. your
employer or you still own the copyright, but there are restrictions on

If the employer does own it, you may not have had permission to license it
> under GPL to begin with.  I would recommend clearing this up first.
>  Or is that just for linking in the C sense?
> >
> As people have noted in the past, GPL is bound by copyright law, which
> ultimately determines whether a work is derivative of another.  We can't
> give you a definitive answer on this.

It is not that we are evading this question, but the issue is rather
complex. You need to ask your lawyer for a legal opinion.

In general, do not assume it is linking in whatever sense.

Does anyone know the in's and out's of relicensing a python module this way?
> >
> If you do own the copyright, you can license it under as many (or few)
> licenses as you'd like, in any order.  Thus, there's no problem with adding
> a separate license.

I do not think the issue is that simple, especially if your program uses
other programs as building block as you will have obligations for using
those programs. Again, ask your lawyer.

And what license do most python modules use?
> >
> Don't know.

That really does not matter. What matters is the licenses you get when you
license those modules that you use in your python module. You have to make
sure they do not conflict with each other.

It is also not a defense to assume your python modules came with the most
popular python module license if it does not come with any notice. You have
the obligation to find out the license your python module uses or otherwise
you do not have any right to use it under the law.

Moreover, this is a complex question. Python website will have information
on the license python uses. Python modules' main repository site will
probably give you a statistics picture of which is the most popular license
for all modules inside it. Even then, it does not take into account modules
in the wild. Moreover, the python module repository site may restricting
itself to modules on certain licenses only.

How hard would it be to take a GPLv2 python module and relicense it to GPLv2
> > and something else just for my employer?
> >
> IANAL, but all you'd have to do is give your employer a separate copy of
> the code (or really just a notice), with an exclusive non-sublicensable
> license.

IANAL, the situation is not that clear cut. Flaschen's method looks OK for
non lawyers like me. It also looks like the way MySQL is doing. However,
your problem is the license of the python modules you used in your module
might restrict what you can do. You need to ask your lawyer.

You might have to have your own lawyer independent of your employer's in
this case. Doing this separate license to employer thing means you is doing
the distribution.( If your employer agree to such a licensing scheme, they
had conceded that you own the copyright. ) You have to understand that if
GPL kicks in, it is you who have the obligation to your module provider(s),
NOT your company. Your company lawyer would be there to defend the company,
not you personally. He or she might work against you to defend the company.

Best Regards,
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