Hindsight bias is recognized as being a significant psychological barrier to properly examining claims.[1]  As recognized by the court in W.L. Gore & Associates, Inc. v. Garlock, Inc., "[i]t is difficult but necessary that the decision maker forget what he or she has been taught . . . about the claimed invention and cast the mind back to the time the invention was made (often as here many years), to occupy the mind of one skilled in the art."  (721 F.2d 1540, 220 USPQ 303, 313 (Fed. Cir. 1983), cert. denied, 469 U.S. 851 (1984)).  Pre-AIA 35 U.S.C. § 103(a) attempts to limit hindsight bias by stating that claims are obvious if "the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art."[2]  (Emphasis added.)  Indeed, "[t]he requirement 'at the time the invention was made' is to avoid impermissible hindsight."  (MPEP § 2141.01(III)). 

One of the most effective tools against hindsight bias, the teaching, suggestion, or motivation ("TSM") test, required that some teaching, suggestion, or motivation must be found in the prior art to combine elements shown in the prior art references. (See e.g.Winner Int'l Royalty Corp. v. Wang, 202 F.3d 1340, 1348 (Fed. Cir. 2000)).  However, the Supreme Court in KSR International Co. v. Teleflex Inc.[3] ("KSR") severely reduced the ability of applicants and patentees to argue against hindsight reasoning by stating that the TSM test is but one test that may be used to make an obviousness determination.  (See e.g.KSR at 418-22).  The holding in KSR affords examiners and challengers to the validity of claims significant flexibility in formulating an obviousness rejection, which is increasingly more difficult for applicants and patent practitioners to combat.

Illustrative of the hurdles facing improper hindsight arguments, the following MPEP section, familiar to many practitioners, is commonly used by examiners to side step the argument without any actual analysis:

it must be recognized that any judgment on obviousness is in a sense necessarily a reconstruction based upon hindsight reasoning.  But so long as it takes into account only knowledge which was within the level of ordinary skill at the time the claimed invention was made, and does not include knowledge gleaned only from the applicant's disclosure, such a reconstruction is proper.  (MPEP 2145(X)(A)), quoting In re McLaughlin, 443 F.2d 1392, 170 USPQ 203 (CCPA 1971)).

In view of this "guidance" to examiners, it would seem that improper hindsight arguments have fallen by the wayside; at best a tack-on argument against a prima facie case of obviousness.  However, a nonprecedential opinion of the Court of Appeals for the Federal Circuit ("CAFC") in Purdue Pharma L.P. v. Depomed, Inc. ("Purdue") illustrates that improper hindsight arguments may still have some teeth.

Purdue highlights that while KSR has made it more difficult to make an improper hindsight argument, in that the TSM test is merely one test that may be used to determine obviousness, the bedrock principles of avoiding improper hindsight must still be adhered to.  Specifically, (1) there must be a reason to combine elements of separate references in the specific manner as claimed; and (2) the problem to be solved must be gleaned from the prior art, and not from the applicant's/patentee's specification.  (See, e.g.Purdue at 10-11).

The ultimate issue on appeal in Purdue was whether interrelated teachings of the prior art and a solution to the problem to be solved, without more, satisfy the appellant's burden of showing that a person having ordinary skill in the art would have had a reason to combine the teachings of the prior art references and would have had a reasonable expectation of success from doing so.  (See, e.g.Purdue at 10-12).

Much to the chagrin of Purdue Pharma L.P. ("Purdue"), the court declined to approach this issue with the "expansive and flexible approach" that was set forth in KSR.  (Slip Op. at 8).  Although the court conceded that in order to determine obviousness, "one may look to 'interrelated teachings' of multiple references, or a 'problem known in the field of endeavor,' to determine whether there was an 'apparent reason' to combine the prior art teachings 'in the fashion claimed by the patent at issue,' " the court turned KSR against Purdue by stating that "the Board correctly recognized that 'a patent . . . is not proved obvious merely by demonstrating that each of its elements was, independently, known in the prior art.' Indeed, it remains 'important to identify a reason that would have prompted a person of ordinary skill in the relevant field to combine the elements in the way the claimed new invention does.' "  (Slip Op. at 10, internal citations omitted,citing KSR, 550 U.S. at 418, 420). 

Applying the above noted teachings of KSR, the court stated that although the interrelated teachings of the prior art references disclosed every element of the claims at issue, Purdue failed to "make a sufficient showing that is more than 'mere conclusory statements,' to establish a reason that would have prompted a skilled artisan to combine the prior art teachings in the way of the claimed invention."  (Slip Op. at 11, citing KSR at 418-189).  Rather, Purdue's "expert opined generally on the interrelated teachings of those references, but did not explain in sufficient detail how or why a skilled artisan would have been motivated to combine the" features of the prior art references.  (Slip Op. at 11). 

Alternatively, Purdue argued, the problem to be solved provides the motivation to combine the prior art references.  (See e.g.Slip Op. at 8).  Specifically, "the problem to be solved provides a further reason to combine [the prior art references], for those references already solved the problem by teaching the drug release profile and other limitations of the challenged claims."  (Id.).  The court found Purdue's position to be untenable in that Purdue "failed to demonstrate to the Board that the problem was known in the art or that [the asserted] formulation of the problem was derived directly from the prior art, rather than from the challenged claims."  (Slip Op. at 11).  Indeed, "[d]efining the problem in terms of its solution reveals improper hindsight in the selection of the prior art relevant to obviousness"  (Id., citing Insite Vision Inc. v. Sandoz, Inc., 783 F.3d 853, 859 (Fed. Cir. 2015)). 

Finally, the court found that Purdue failed to explain how one having ordinary skill in the art would have had a reasonable expectation of success in making the proposed combination.  Specifically, "both parties' experts testified on the large number of formulation considerations in play when designing a drug formulation."  (Slip Op. at 12).  In fact, "Purdue did not sufficiently explain why a skilled artisan would have expected that the [one] formulation could be modified to incorporate the 'swelling' and 'substantially intact' features of [a second], without affecting the other desired properties."  (Id.).  In view of the foregoing, the court found that Purdue failed to meet its burden to show that the challenged claims were obvious over the prior art references.

The ultimate result of Purdue highlights the limits of the KSR approach to determining obviousness.  It is not enough to rely on interrelated teachings of prior art references without more than mere conclusory statements that one having ordinary skill in the art would have reason to combine the elements taught in the prior art.  Although each element of the claim may be found in prior art references, as stressed in Purdue, there must be some reason that a skilled artisan would have combined the elements taught in the prior art references.  Further, the court made it clear that the sole reason for making the proposed combination cannot be a problem defined in terms of its solution.  Specifically, the problem to be solved must be gleaned from something other than the applicant's/patentee's specification. 

Of further note, the importance of this standard extends to non-analogous art arguments.  For example, obviousness rejections based on non-analogous art are untenable when the prior art is selected because it is reasonably pertinent to the problem faced by the inventor, when the problem has been defined in terms of its solution.  As stated by the court in Monarch Knitting Machinery Corp. v. Fukahara Industrial & Trading Co., Ltd.,[4] "[b]y importing the ultimate solution into the problem facing the inventor, the district court adapted an overly narrow view of the scope of the prior art.  It also infected the district court's determinations about the content of the prior art."  Such an argument is indicative of improper hindsight when selecting the prior art.  (See e.g.Monarch).

Although the holding of Purdue is narrowly decided in view of the highly technical nature of the claims, the underlying principles of hindsight reasoning detailed in Purdue are still an important aspect of formulating a proper obviousness rejection.  Practitioners should ensure that examiners are providing something more than mere conclusory statements as to why one having ordinary skill in the art would be motivated to combine the prior art references.  Attention should be paid to whether the examiner has provided specific reasoning for the proposed combination and whether or not the problem to be solved is relied upon as the reasoning for the combination.  If nothing else, Purdue is a reminder that while KSR broadens the potential bases for an obviousness rejection, there still must be a "reason" for the combination regardless of the basis for the rejection.