Static v. Dynamic Linking -- redux

David Johnson david at
Sat Mar 16 05:15:47 UTC 2002

On Friday 15 March 2002 01:02 pm, Lawrence E. Rosen wrote:

> I say "almost completely" because I think the burden of proof should
> shift to the creator of an alleged derivative work to demonstrate either
> (1) the DLL was designed and intended to be invoked dynamically by
> programs that are not "derivative works" of that DLL, or (2) the
> proprietary program that invokes that DLL doesn't use dynamic linking
> simply to get around the [GPL] license.

Your first point is interesting. I'm wondering how one could demonstrate that 
a library was meant to be invoked by non-derivative works. Here the criteria 
that I would use: the library is a separate distinct package, and the 
interface for the library is documented. These two criteria tell me that the 
library was intended to be used for multiple programs by multiple authors.

> I don't believe that licensing the DLL under the GPL *automatically*
> negates alternative 1 above -- since the GPL doesn't unambiguously say
> that.  On the other hand, if the DLL were licensed under a [non-open
> source and non-free] license that expressly disallowed use through
> certain kinds of dynamic linking, then the creator of that linking
> program would have a lot of explaining to do!

The purpose of a proprietary license is not to reiterate copyright law, but 
to restrict and regulate the rights that the user already possesses. If 
linkage constituted derivation, then all the proprietary library needed to do 
to prevent linkage would be to have a simple one-line copyright notice. But 
since there are libraries that do have restrict dynamic linkage, then the 
authors of their licenses must believe that dynamic linkage is a right that 
normally belongs to the user.

I would suggest that proprietary licenses that restrict linkage do so by 
restricting the *use* of the library, and not by being redundant with regards 
to copyright law.

David Johnson
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