I have in mind a case noted by the ipwatchdog site, I believe. The following isn't the case I had in mind, which was more extreme still, and much more recent, but here's a start:
A reference “is ‘publicly accessible’ upon a satisfactory showing that [the reference] has been disseminated or otherwise made available to the extent that persons interested and ordinarily skilled in the subject matter or art exercising reasonable diligence, can locate it.” Bruckelmyer v. Ground Heaters, Inc., 445 F.3d 1374, 1378 (Fed. Cir. 2006).
…
For instance, in Electronic Frontier Foundation, the Board determined that when a reference was only temporarily publicly available via a URL but no longer exists at that URL, the petitioner must show that the reference can be found through another source not including the URL. Electronic Frontier Foundation v. Personal Audio, LLC, IPR2014-00070, Paper 21 at 22 (PTAB Apr. 18, 2014) (Decision, Institution of Inter Partes Review).
[Note that the information being up somewhere where most people wouldn't be able to find easily enough doesn't suffice. "Reasonable diligence" isn't defined, but clearly isn't intended as a high bar.]
Printed publications can be an exception - but both those words are highly subject to interpretation.
Sure. Essentially the courts are affirming that the system is “first to file” and not “first to invent”. You cannot quietly invent something and then claim ownership after someone else patents the same idea. If prior art could be private, then the system would still be de facto “first to invent”.
How well known something must be is obviously going to be subject to interpretation. If you tell your co-worker at the bar, that’s probably not sufficient. If you publish on your blog that no one knows about, that’s probably also not sufficient. If you publish in a journal, that probably is more than sufficient. If you cannot reasonably claim that the other inventor should have been able to find your prior art, then the courts will rule against you.
