On Thu, Sep 8, 2022 at 3:52 PM Clem Cole <clemc@ccc.com> wrote:
On Thu, Sep 8, 2022 at 12:51 PM segaloco via TUHS <tuhs@tuhs.org> wrote:
Both Coherent and 4.4BSD have stuck out to me as examples of not-quite-so-clean-room implementations that did well enough (more than enough for BSD) and didn't die a fiery death in litigation (as much as USL tried...). 
BSDi/UCB vs. USL was a different kettle of fish altogether.   As has been discussed here extensively (and needs not to be repeated), that suit was about Trade Secrets and >>ideas<< that make up what we call UNIX.   The real interesting thing about that case is that had USL/AT&T won, the repercussions for the industry would have been way beyond just BSDi - but all of the UNIX clones and many of us on this list who had been "mentally contaminated" with AT&T's ideas (I still have my 'mental contamination' button somewhere in my archives).

Yes. Indeed. It devolved to a copyright battle with the ultimate result being a preliminary ruling that 32V (and V6 and V7 likely) had no copyright protection because AT&T had distributed too many copies without the required (at the time) copyright notices...  That preliminary ruling is what forced the settlement of the suit, and is the reason that 4.4BSD-lite had a bunch of files with AT&T copyrights on them with permission to redistribute liberally...

These days, in open source cleanroom is rarely done except in extraordinary cases. It's easier to read the code and reimplement because copyright covers only the typing...