GPL and closed source

David Woolley forums at
Fri Jun 3 21:12:27 UTC 2011

Mahesh T. Pai wrote:

> If the question is whether GPL allows GPL'ed code to use functionality
> provided by libraries under other licenses, the answer is, (a) yes it
> does and (b) GPL does not fetter a user's freedom to use the GPL'ed
> code any manner he likes - that includes depending on non-free libraries. 

However, copies can only be redistributed if the licences for all the 
GPLed components grant specific permission to link against that 
proprietary library.

Giving someone software under a purported GPL licence without giving 
them dispensations to link with the proprietary libraries makes the GPL 
pretty pointless.  It would be better to use a licence that reflects the 
intended redistribution terms.

I believe you can actually modify and link GPLed code with proprietary 
code when you are not the owner and don't have a dispensation, but you 
are then not allowed to give it to anyone else.

> Please note that FSF's answer to "Can I write free sfotware that uses
> non-free libraries" and "What legal issues come UP if I use GPL
> incompatible lbiraries with GPL software?" 
> are mostly technical; not legal. If you read clearly, the text says
> "please do not do it - write a GPL compatible, free software library".

"It" here, is issuing a dispensation.

However, note that the intention of the GPL is that most GPLed programs 
should not be the sole intellectual property of the current author.  By 
linking with proprietary libraries, you forego the right to distribute 
versions that are derivatives of other GPLed code.

Note the disputed legal issue is about when a binary program is a 
derivative work of a software library.
David Woolley
Emails are not formal business letters, whatever businesses may want.
RFC1855 says there should be an address here, but, in a world of spam,
that is no longer good advice, as archive address hiding may not work.

More information about the License-discuss mailing list