How To Break The GPL

Andrew J Bromage ajb at
Sat Mar 4 01:26:38 UTC 2000

G'day all.

On Fri, Mar 03, 2000 at 10:45:47AM -0500, John Cowan wrote:

> This is offered in the spirit of "How To Make Atomic Bombs", and does
> *not* mean that the author approves of the conduct described herein.


> Now who has violated Trent's copyright?  Not Alice: she did not modify or
> distribute Trent's work. 

Alice wrote and distributed what is, in the opinion of RMS, a derived
work of Trent's work and thus her work is covered by the GPL.  

In the discussion which follows, I'll restrict myself to the case of
a non-GPL'd work usig a GPL'd library.

This is probably the most legally controversial part of the GPL.  It's
difficult to say whether or not a program which uses a library is a
derived work of that library.  If I were a judge (and IANAL so this is
unlikely to say the least), I would probably decide on a case-by-case

If, for example, there exist non-GPL'd implementations with an identical
interface and equivalent functionality, I would have to rule that it is
_not_ in the spirit of "derived work" to class the program as a derived

Let's make it a little more specific and ask yourself "is Alice's program
a derived work of Trent's code"?

	Alice writes a graphics program (perhaps a game, for example)
	which is developed using Trent's GPL'd implementation of OpenGL.
	In this case, there are many proprietary implementations of
	OpenGL available.  When Alice sends her sh/make/English
	instructions to incorporate Trent's code include an instruction
	_not_ to download Trent's code if there is already an
	implementation on Bob's machine.

Andrew Bromage

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