Q: Combining proprietary code and GPL for in-house use
My program works well without the GPL library. Now if I sell this program,
and add a module that the customer may link with the GPL library, would I
violate the GPL of the library, and why ?
No court has ruled on this, but the FSF position is that this would
violate the GPL. The GPL would apply because the code is specifically
designed to function as a combination including the GPL-covered
The fact that it is also specifically designed to function without
that library is neither here nor there. Its ability to work that way
is innocent and does not constitute a violation of the GPL, but it
doesn't cancel or eliminate the violation.