Burden shifting at the USPTO

Note the discussion of burden-shifting in Ex parte Sakamoto

“[W]here the Patent Office has reason to believe that a functional limitation asserted to be critical for establishing novelty in the claimed subject matter may, in fact, be an inherent characteristic of the prior art, it possesses the authority to require the applicant to prove that the subject matter shown to be in the prior art does not possess the characteristic relied on.” In re Swinehart, 439 F.2d 210, 213 (CCPA 1971). This flexibility in the burden of proof placed on the Patent Office is afforded because “[a]s a practical matter, the Patent Office is not equipped to manufacture products by the myriad of processes put before it and then obtain prior art products and make physical comparisons therewith.” In re Brown, 459 F.2d 531, 535 (CCPA 1972). In order to shift the burden of proof, the Examiner must provide evidence or reasoning to establish a sound basis for the Examiner's belief that the missing descriptive matter is necessarily present in the reference. See In re Spada, 911 F.2d 705, 708 (Fed. Cir. 1990). Once the Examiner has done this, the burden to overcome, with argument or evidence, the apparent identity of Appellants’ claimed device and that of the prior art shifts to Appellants. Id.

Contemplate also In re Best.

Also in the Board decision:

The examiner bears the initial burden of setting forth a reasonable explanation as to why the scope of protection provided by the claims is thought to be not adequately enabled by the description of the invention provided in the specification. If that burden is met, the burden then shifts to the applicant to provide proof that the specification is indeed enabling. In re Wright, 999 F.2d 1557, 1561-62 (Fed. Cir. 1993). “[T]he Patent and Trademark Office must substantiate its rejection for lack of enablement with reasons.” In re Armbruster, 512 F.2d 676, 677 (CCPA 1975) (emphasis in original).

and

“‘The enablement requirement is met if the description enables any mode of making and using the invention.’” Johns Hopkins Univ. v. Cellpro Inc., 152 F.3d 1342, 1361 (Fed. Cir. 1998) (quoting Engel Indus., Inc. v. Lockformer Co., 946 F.2d 1528, 1533 (Fed. Cir. 1991)).
“[E]nablement requires that the specification teach those in the art to make and use the invention without ‘undue experimentation.’ That some experimentation may be required is not fatal; the issue is whether the amount of experimentation required is not ‘undue.’” In re Vaeck, 947 F.2d 488, 495 (Fed. Cir. 1991) (citation omitted, emphasis in original). “Whether undue experimentation is needed is not a single, simple factual determination, but rather is a conclusion reached by weighing many factual considerations.” In re Wands, 858 F.2d 731, 737 (Fed. Cir. 1988). The factual considerations discussed in Wands are: (1) the quantity of experimentation necessary to practice the invention, (2) the amount of direction or guidance presented, (3) the presence or absence of working examples, (4) the nature of the invention, (5) the state of the prior art, (6) the relative skill of those in the art, (7) the predictability or unpredictability of the art, and (8) the breadth of the claims. Id.
The specification need not disclose what is well known in the art. Lindemann Maschinenfabrik GmbH v. American Hoist & Derrick Co., 730 F.2d 1452, 1463 (Fed. Cir. 1984).