A prior art reference will anticipate a later claimed invention where that prior art reference contains each and every element and limitation of the claimed invention. However, there are situations where the prior art does not specifically disclose an element or limitation but will still be treated, for purposes of defeating the novelty of a later claimed invention as if it had. Elements that are not disclosed explicitly but that are always and necessarily present in the prior art reference are deemed inherent elements. Inherent elements cannot be a matter of possibilities or probabilities; they must be inherent to the disclosure and such inherency must be demonstrable. As it has been sometimes expressed, the inherent limitation or element must necessarily flow from the practice of the prior art disclosure. In the case of inherent anticipation,simply practicing the prior art will manifest the claimed invention, even though the prior art does not specifically describe all of the elements or limitations necessary to,or resulting from the practice of the art. If this sounds confusing based on all that was said about anticipation before, please don’t feel bad because confusion seems to be inherent to this doctrine!

To better understand this oftentimes nebulous and occasionally controversial doctrine,it is instructive to look at some examples that should help more fully illuminate some of the contours and contexts of inherent anticipation. As an example, consider a chemist who has been working very diligently in the area of trying to discover new compounds suitable for the production of polymers that can in turn be used to prepare films, fibers, and molded parts. In particular, he believes that 2,2_,6,6_-tetramethylbiphenyls (TMBP), which is 4,4_disubstituted with CO2H, would be a good agent for polymerization. The chemist measured several of the properties of the compound and claimed the compound, as shown in Figure below.
A prior art reference was cited that disclosed, among other compounds, the exact compound of formula I. However, the reference made no mention that the compound was suitable for the production of polymers. Given the failure of the prior art to teach the suitability for polymer production limitation, does the prior art reference disclose each and every element and limitation as required in order for it to be an anticipating reference? The short answer is yes. The reason for this is that a molecule and its properties are presumed to be inseparable. Thus the suitability of the compound


FIGURE :Claimed polymerization agent.

of formula I for polymer production is inherent to the structure itself. Therefore, the compound of formula I disclosed in the prior art reference will be assumed to have the same polymer suitability as the compound claimed.
A second example demonstrates just how diverse the prior art can be. Although everything under the sun made by man might be suitable subject matter for a U.S.patent, suitable subject matter for prior art is even broader. In fact, prior art includes not only everything made by man but made inside of man as well. Schering-PloughCorporation is the patent assignee of patent U.S. 4,659,716 (the ’716 patent), which contains claims to descarboethoxyloratadine (DCL), which is the descarboethoxyhuman metabolite of loratidine (an antihistamine marketed as Claritin_R ). Loratadine is the subject of a different patent, U.S. 4,282,233 (the ’233 patent), also held by Schering-Plough. The structures of the two compounds are shown in Figure below.

The ’233 patent is available as prior art against the ’716 patent (the ’233 patent issued on August 4, 1981, over 1 year before the earliest filing date claimed for the ’716patent, February 15, 1984).
Several generic drug makers wished to market a generic drug version of loratidine,and filed abbreviated new drug applications (ANDAs) with the FDA. Since the ’233 patent covering loratidine would be expired by the time the generic products came to market, there was no issue of infringement of that patent. However,

Claimed polymerization agent.

FIGURE : Structure of loratidine and descaroethoxyloratidine.

Structure of loratidine and descaroethoxyloratidine.

FIGURE :Asserted claims from ’716 patent.

Schering-Plough’s later ’716 patent would still be in force, and so Schering-Ploughsued for infringement of claims 1 and 3 of the ’716 patent (shown in Figure above).Although the generic companies were interested in manufacturing loratadine, the federal court hearing the case construed claims 1 and 3 to cover DCL in any form(both parties agreed to this construction). This is because claims 1 and 3 simply do not provide any limitation as to the purity of DCL nor the quantity required for infringement of the claim. However, you may have noticed that the structure of loratidine does not fall within the scope of the ’716 patent and so what is the basis for infringement? As it turns out, it was well established by the time of the infringement suit that the administration of loratidine to a human subject necessarily results in the formation of DCL, the subject of claims 1 and 3 of Schering-Plough’s’716 patent.38 This means that the pharmaceutical use of loratidine, the subject of the Schering-Plough’s ’233 patent, would generate the structure corresponding to DCL,the subject matter of the ’716 patent. It would appear that Schering-Plough has come up with a very clever way to effectively extend the useful life span of their loratidinepatent by covering its human metabolites in a later patent.

However, the federal court poured cold water on this idea because they found that claims 1 and 3 of the Schering-Plough ’716 patent were invalid because they lacked novelty over Schering-Plough’s own disclosure in its own prior art ’233 patent.In particular, the court found that the ’233 patent disclosed loratidine and methods of using loratidine, including administration to humans. According to the court’s reasoning, even though DCL was not specifically disclosed in the ’233 patent, DCL would always and necessarily be formed when loratidine was administered according to the methods taught in the invention. In other words, DCL necessarily flows from the teaching of the ’233 patent itself. Further, the court noted that it did not matter whether the metabolite had actually been formed in the ’233 patent, it was simply sufficient that an enabling disclosure had been provided for its production. Since this disclosure was made more than 1 year prior to the ’716 filing date, claims 1 and 3 of ’716 patent were anticipated under §102(b). Finally, the court noted that a metabolite could be claimed1) in a pure form, 2) as a pharmaceutical composition, or 3) in a method of use claim.

In fact, additional claims in the ’716 patent covering pharmaceutical compositions and methods of treating allergic reactions by administering DCL were not anticipated by the ’233 patent. Can you see though why this did not help Schering-Plough in the infringement case?

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