[Fwd: Re: CDDL+GPL and stuff]

[Iain Barker]

From: Alex van der Wolk <avdwolk at xs4all.nl>
> the discussion on whether something is a derivative work can
> be held to the end of times. Arnoud is right that there is no clear
> rule of thumb. There are some examples (most of which are not from
> software cases) as to what constitutes a derivative work, but most
> often you'll have to go on common sense.


And not forgetting of course that there are significant variations in national legislations which implement copyright law.  For countries which are signatories, the Berne convention and/or the WIPO Copyright Treaty offer some standardisation, but the interpretation or definition of what constitutes a derived work of software is not explicitly codified.

Under USA copyright law for example, the abstraction-filtration-comparison and methods used by the 10th circuit court provide one commonly referenced example of an how to determine derivation. But ultimately it remains a subjective interpretation on a case-by-case basis.
http://digital-law-online.info/cases/28PQ2D1503.htm