Quoting Bruce Perens (bruce@???):

> OK, I don't see much reason to ask Google to help with *that.*
>
> There hasn't been a litigated case, that I know of, of transformative fair
> use as applied to Free Software.

For leading cases, you'd naturally look to non-software ones, which
is a perfectly natural thing for lawyers and judges to do, even if it
isn't for software geeks. (Code is considered a 'literary work' --
pause for irony -- within copyright law.)

As I'm sure you know, commentary/criticism is one of the enumerated
legitimate purposes for creation of infringing derivative works with a
fair use defence, that being helpful for the first of the four factors
(in USA copyright law), _all of which_ the judge is required (17 U.S.C.
107) to consider and weigh, on a case-by-case basis -- possibly in
addition to other concerns (these four being a statutory minimum):

1. the purpose and character of the use, including whether such use is
of a commercial nature or is for nonprofit educational purposes
[RM: encouraging scholarship, research, education, and commentary.]
2. the nature of the copyrighted work;
[RM: encouraging copying from informational work more than works
of fiction, and from published works much more than from unpublished ones.]
3. the amount and substantiality of the portion used in relation to the
copyrighted work as a whole; and
4. the effect of the use upon the potential market for or value of the
copyrighted work.

The reason I review the above is:

> I could, if it were litigated, produce a good expert testimony that
> grsecurity does fail the fair use test because it causes market damage
> to Linux and the GPL's purpose of accumulating additional Free
> Software as modifications are produced.

Non-sequitur conclusion. US judges are required by 17 U.S.C. 107 to
consider and weigh all four factors as part of any determination of fair
use. No single one of them is dispositive.

My friends at Nolo Press said: 'A court, faced with this argument,
weighs four factors and, if the weight of the factors is in favor of the
defendant, declares that the unauthorized use of the material is
permitted.'
http://www.nolo.com/legal-encyclopedia/fair-use-the-four-factors.html

(I don't know what it says about me that I used to await eagerly every
issue of _Nolo News_, and not just the Lawyer Joke Page on the back,
either.)

Library of Congress Copyright Office elaborates: 'In addition to the
above [RM: the four factors], other factors may also be considered by a
court in weighing a fair use question, depending upon the circumstances.
Courts evaluate fair use claims on a case-by-case basis, and the outcome
of any given case depends on a fact-specific inquiry. This means that
there is no formula to ensure that a predetermined percentage or amount
of a work—or specific number of words, lines, pages, copies—may be used
without permission.'

https://www.copyright.gov/fair-use/more-info.html