Inherent Anticipation – How Certain Is Certainty?

In pharmaceutical cases, infringement defendants will argue that an asserted patent claim is anticipated or obvious. Often it is difficult to prove a patent claim obvious.Seemingly trivial and mundane modifications of the prior art could turn out to be “unexpected.”Motivations to modify the prior art could be hard to prove in a counterfactual back-in-time analysis.Who exactly is a “POSITA”?Whether hindsight has been improperly applied in such an analysis is often up to debate.Not to mention that a defense of obviousness tends to open up discovery into a host of “secondary considerations” that could be very costly.

Anticipation, on the other hand, is straightforward and binary – you either find the exact claimed subject matter in the prior art, or you don’t.However, sometimes the prior art leaves a gap – one element of the claim is missing from the express disclosures.For example, the prior art might describe with sufficient detail a chemical reaction, or a crystallization process, without disclosing the identity or analytical data of the product.Is the product necessarily the (later claimed) chemical compound or crystal form?As another example, the prior art might disclose a clinical study using drug “X”, without disclosing in detail the population of study subjects. Was the drug administered to a patient with condition “Y”, which method later was claimed in a patent?This is where inherency can be helpful.The problem, then, is to prove the inherent element to certainty.Mere probability is not enough.

Proving certainty can be daunting.A patent challenger could reproduce the prior art method ten times, coming up with the claimed subject matter every time, but the patent owner could show or just argue that the eleventh time would yield something different.In In re: Armodafinil Patent Litigation (D. Del. MDL No. 10-md-2200), the defendants’ experts reproduced a prior art method at least four times, each time coming up with the claimed Form I polymorph of armodafinil (albeit sometimes in mixture with other form or forms).The patent owner’s experts, on the other hand, ran the prior art method “using different, but reasonable experimental conditions that the court find credible,” and made amorphous products instead.These results, plus an argument that small variations in carrying out the prior art method could result in different products, carried the day for the patent owner.Inherent anticipation was not found in that case.

So what can a patent challenger do to prove inherent anticipation?

“Normal and Usual” Reproduction of Prior Art Method

In Cephalon v. Sun Pharma (D.N.J. Case No. 11-cv-5474), the patent challenger defeated a preliminary injunction motion by demonstrating the viability of an inherent anticipation defense.The patent in the case claims an anhydrate form of tiagabine HCl. The defendant’s expert made one reproduction of a prior art method which disclosed heating tiagabine HCl monohydrate on a hot-stage XRPD machine, and turned the sample into the claimed anhydrate form.The defendant also found evidence in the plaintiff’s document production that “strongly suggests similar results occurred [previously].”The patent owner, on the other hand, pointed to two experimental runs in which the heated material was crash cooled in a dry ice bath or in ice.Because the prior art disclosures did not mention such “extreme conditions,” the district court disregarded these results, because these methods are not “normal and usual.”

Typically, when inherent anticipation is at issue, the patent owner would poke holes at the patent challenger’s reproduction of prior art methods.For example, the patent owner could argue that the reproduction did not follow the prior art method precisely, or that variations of method steps and conditions could result in different results. Sun Pharma’s success here shows that two can play this game.The patent challenger can also poke holes at the patent owner’s reproduction of prior art methods, if such reproduction went beyond what was “normal and usual.”In the Cephalon v. Sun case, Cephalon did not try to reproduce the prior art method during litigation, but relied on previous heating experiments to argue that different methods of heating the monohydrate could result in amorphous material.However, the argument would have been the same if Cephalon did try to carry out the dry ice or ice cooling method during the litigation—that such “reproduction” was no reproduction of prior art method at all.

Can Inherency Be Proven Statistically?

Mathematically speaking, certainty is not probability, no matter how overwhelming the odds are. However, we live in a finite world, and at some point probability does become certainty.Consider this example. Suppose a clinical study for treating disease “A” using drug “X” was conducted, and the results were published. Years later, it became known that 50% of the patients suffering from disease “A” also suffer from condition “Y”, and a patent issues to cover administering “X” to a patient with “Y”.Is the patent claim inherently anticipated by the published clinical study?If the study’s design did not exclude patients with condition “Y”, there is a 50-50 chance that any particular subject of that study had condition “Y”. If the study involved 100 patients receiving “X”, the probability that none of these patients had “Y” would be something like 0.0000000000000000000000000001%.In other words, even if the entire world’s population suffered from disease “A”, one could divide the billions of people into groups of 100 and still be 99.999999999999999999% certain that every such group would include at least one person with condition “Y”. At some point it does seem outlandish to deny that inherent anticipation had occurred.

Some Considerations on Inherent Anticipation

A patentee may argue that the now-claimed feature was not actually known in the prior art (even though it was, as a matter of fact there) or that even though present, the POSITA could not appreciate that it was there in the art. There is no requirement that a POSITA would have recognized the inherent disclosure at the time of invention, but only that the subject matter is in fact inherent in the prior art reference. Schering Corp. v. Geneva Pharm. Inc., 339 F.3d 1373, 1377 (Fed. Cir. 2003) (rejecting the contention that inherent anticipation requires recognition by a person of ordinary skill in the art before the critical date and allowing expert testimony with respect to post-critical date clinical trials to show inherency). This also means that when the inherent feature was in a product that was also sold (even though seller or buyer didn’t know of the feature), this sale also created the on-sale bar. Abbott Labs v. Geneva Pharms., Inc., 182 F.3d 1315, 1319 (Fed.Cir.1999) (“If a product that is offered for sale inherently possesses each of the limitations of the claims, then the invention is on sale, whether or not the parties to the transaction recognize that the product possesses the claimed characteristics.”).

How should you think about inherent anticipation when drafting a patent application or during litigation? A patent drafter may need to evaluate how much detail to put into the application that balances the need for sufficient disclosure for Section 112 purposes and whether the additional detail provides enough information that when the disclosure becomes prior art, the detail is sufficient for later inherent anticipation purposes. Further, when considering infringement the patentee may need to decide on whether the claim construction should be narrow or broad. For example, if the patent claims a Form X crystal polymorph. If the defendant does not use Form X crystal, it’s harder to show infringement. The patentee may argue that the accused product contains at least a single crystal of Form X, and if it can be shown that the accused product contains a single crystal of Form X, then infringement is shown. If the claim construction is for a certain quantity of Form X, then the accused product may not infringe if there is not that quantity. On the other hand, if the patentee needs to argue the single crystal theory, then if the prior art had the single crystal, shown by inherent anticipation (and whether it was known or appreciated or not), then the claim is invalid. So there is certainly a tension between how inherent anticipation is determined.

How We Can Help

Upadhye Tang LLP, (stay tuned to our name change to Upadhye Tang LLP) stands ready to help clients in patent analysis, infringement suits & defenses, and in PTAB proceedings. Contact Yixin Tang at for more information.


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