The Patent Trial and Appeal Board (PTAB) typically institutes a post-grant proceeding (IPR, CBM, or PGR) designating one or more specific printed prior art references against a particular patent claim.  However, this does not eliminate possible roles for other, collateral prior art references in the record of the proceeding.  The Federal Circuit’s opinion in Ariosa approves judicial reliance upon a collateral reference of record that evidences “the knowledge that skilled artisans would bring to bear in reading the prior art identified as producing obviousness.”1 

Even prior to Ariosa, the PTAB has been making, or omitting, findings of fact on the level of ordinary skill in the art based upon earlier Federal Circuit decisions, stating:  

The level of ordinary skill in the art need not always be expressly defined.  It can be reflected by the prior art of record.  See Okajima v. Bourdeau, 261 F.3d 1350, 1355 (Fed. Cir 2001); In re GPAC Inc., 57 F.3d 1573, 1579 (Fed. Cir. 1995); In re Oelrich, 579 F.2d 86, 91 (CCPA 1978).2

On its way to concluding that petitioner in Ariosa had failed to provide sufficient rational support for a legal conclusion of obviousness, the PTAB found that “. . . neither Petitioner nor [Petitioner’s expert] Dr. Morton explains why Exhibit 1010 could not have been presented as part of the asserted ground of unpatentability in the first instance with the Petition.  Therefore we accord this aspect of Dr. Morton’s testimony no weight.”3  But, in vacating the PTAB’s finding and remanding the case to the PTAB for consideration of Exhibit 1010, the Federal Circuit said:

Art can legitimately serve to document the knowledge that skilled artisans would bring to bear in reading the prior art identified as producing obviousness.  Randall, 733 F.3d at 1362-63.  Ariosa’s Petitions and opening declarations invoked Exhibit 1010 in that way.4

The Federal Circuit’s remand and language in Ariosa suggest that collateral references made of record in a post-grant proceeding, may properly be referred to by a party, the PTAB, and/or court as relevant evidence relating to any finding of fact with respect to the factual inquiries upon which a legal conclusion of obviousness/non-obviousness may be based.  Similarly, for claim construction, the PTAB and courts routinely use the prosecution history of the patent in question, any references cited in that history, and any extrinsic evidence, provided these are in the record of the proceeding.

Such uses of collateral references of record are consistent with the Federal Circuit’s earlier opinion in In re Cuozzo Speed Tech., LLC where the court said:

Nor does the IPR statute expressly limit the Board’s authority at the final decision stage to the grounds alleged in the IPR petition. It simply authorizes the Board to issue “a final written decision with respect to the patentability of any patent claim challenged by the petitioner and any new claim added under section 316(d). 35 U.S.C. § 318(a).5

In Cuozzo, the court affirmed the PTAB’s final written decision which sua sponte used as grounds for cancellation under § 103 of three claims (10, 14 and 17).  The prior art references in the IPR petition had identified among the stated grounds against only claim 17, which was dependent upon claim 14, which in turn was dependent upon claim 10.  Note that in bothCuozzo and Ariosa the collateral references in question were presented in the IPR record in or with the initial petitions.


  • Petitioners should consider making appropriate collateral references part of the record at the petition stage to enable use thereof in supporting whatever position a party may be advocating or defending. 
  • Patent Owners should consider making appropriate collateral references part of the record at any time.
  • Any party should consider using collateral evidence of record when formulating petitions, responding thereto, and in utilizing any part of the record throughout trial, oral argument, and appeal.