Why USPTO Should Issue Inherency Guidance Memo

By Irving Feit · Law360, April 2, 2024

A patent claim is unpatentable over prior art if each element set forth in the claim is disclosed in one prior art reference or in a combination of references. The elements can be disclosed either expressly or inherently.¹  

The author believes the time is ripe for the USPTO to issue a new guidance memo in regard to the standard for inherency during the examination process.

A patent claim is unpatentable over prior art if each element set forth in the claim is disclosed in one prior art reference or in a combination of references. The elements can be disclosed either expressly or inherently.¹  

The standard for determining whether a claim element is inherently disclosed in a prior art reference was settled many years ago. The standard has been applied remarkably consistently in the courts to this day. However, the standard is frequently misapplied during prosecution in the USPTO.  

This article will illustrate the standard by describing two court cases, one from 1969 and a more recent case from 2022. The 1969 case is Application of Zierden³ from the Court of Customs and Patent Appeals, which was the predecessor of the U.S. Court of Appeals for the Federal Circuit. The 2022 case is Pharmacyclics v. Alvogen from the Federal Circuit.⁴

The article will then compare how the standard is applied in the courts and currently in the USPTO. The author will recommend how the standard can be more consistently adhered to in the USPTO.

The Standard

The standard for establishing both inherent anticipation and inherent obviousness was formulated 85 years ago by the CCPA in Hansgirg v. Kemmer.⁵

In re: Oelrich, decided by the CCPA in 1981, is a case frequently cited for the inherency standard.⁶ The court in Oelrich, citing Hansgirg, stated the standard as follows:

Inherency, however, may not be established by probabilities or possibilities. The mere fact that a certain thing may result from a given set of circumstances is not sufficient. If, however, the disclosure is sufficient to show that the natural result flowing from the operation as taught [in a reference] would result in the performance of the questioned function [claimed], it seems to be well settled that the disclosure should be regarded as sufficient.

As is apparent from the above quote and the cases discussed below, the standard is absolute.

To be inherent in a patent claim whose validity over prior art is at issue, an element disclosed in the prior art must always, necessarily, and without exception be present in the claim.

As was stated by the Federal Circuit in its decision in Persion Pharmaceuticals v. Alvogen Malta Operations in 2019,⁷ for example: “[I]nherency renders a claimed limitation obvious only if the limitation is ‘necessarily present.'”

Application of Zierden

In Zierden, a claim recited a method for removing deposits of alluvium from water, including industrial cooling water, by adding potassium metaphosphate. Alluvium was defined as including, inter alia, silt and mud.

In rejecting the claim as being inherently obvious, the examiner cited two prior art references.

A primary reference disclosed the removal of deposits of “scale” from industrial water by adding potassium metaphosphate to the water. Scale was reported to contain mostly calcium carbonate.

According to the examiner, the secondary reference taught that all industrial cooling waters contain silt and mud. The examiner argued, therefore, that when the water mentioned in the primary reference was treated to remove scale, alluvium would inherently also be removed.

Zierden appealed the rejection to the Patent Office Board of Appeals, now the Patent Trial and Appeal Board. The board affirmed the rejection.

Zierden appealed further to the CCPA. During the appeal, the solicitor relied on the argument of the examiner as confirmed by the board.

Writing for the CCPA, U.S. Circuit Judge Giles Rich,⁸ disagreed with this argument. He pointed out that all industrial waters did not necessarily contain alluvium at the time of carrying out the method to remove scale as was described in the primary reference.

Judge Rich explained, for example, that the industrial water might have been filtered to remove alluvium before being treated to remove scale.

The mere theoretical possibility that the water might not have contained alluvium when it was treated to remove scale in accordance with the primary reference was sufficient to reverse the inherency rejection.

Pharmacyclics v. Alvogen

At issue in the more recent Pharmacyclics case was the validity of Claim 5, which recited a specific crystalline form of a drug that was being tested in a clinical study for treating certain lymphomas. The drug is ibrutinib and the claimed crystalline form is known as Form A.

Ibrutinib was known to exist in multiple crystalline forms, of which Form A is the most stable. The most stable form of a crystal is the most likely to predominate in a mixture of crystalline forms.

According to the alleged infringer in Pharmacyclics, Claim 5 was invalid because two prior art references disclosed the clinical study of ibrutinib. Although not disclosed in the references, the form of ibrutinib actually used in the clinical study was form A.

The Federal Circuit in Pharmacyclics held that the claim was not inherently anticipated. The underlying legal principle used by the court in Pharmacyclics was the same as that used in Zierden more than 50 years earlier.

The mere possibility, and even the probability, that the crystalline form of ibrutinib used in the clinical study was Form A was not enough to maintain a rejection based on inherency.

According to the Federal Circuit in Pharmacyclics, “The question is what is ‘necessarily’ inherent in the anticipating reference.”

Inherency in the Federal Courts

The consistency mentioned above in the standard for inherency in the federal courts over a long period of time has been admirable. From Oelrich and Hansgirg, the courts have maintained this standard, including in the following Federal Circuit decisions:

• Par Pharmaceutical Inc. v. TWi Pharmaceuticals Inc. in 2014;
• Alcon Research Ltd. v. Apotex Inc. in 2012;
• Schering Corp. v. Geneva Pharmaceuticals Inc. in 2003;
• Mehl/Biophile International Corp. v. Milgraum in 1999;
• In re: Napier in 1995;
• In re: King in 1986.⁹

The admirable consistency of the standard in the federal courts would hardly be worth noting were it not for the fact that the consistency during examination in the USPTO is significantly less admirable.

Inherency in the USPTO

The standard for examiners to establish inherency is expressed accurately, although somewhat blandly, in the Manual of Patent Examining Procedure 2112(IV) as follows:

In relying upon the theory of inherency, the examiner must provide a basis in fact and/or technical reasoning to reasonably support the determination that the allegedly inherent characteristic necessarily flows from the teachings of the applied prior art.

Examiners are instructed to follow the guidelines set forth in the MPEP.

It has been the experience of the author in his 40-plus years of prosecuting patent applications in the USPTO, however, that patent examiners, at least those in chemistry and biotechnology art units, either misunderstand or ignore the well-established standard for inherency in the Federal Circuit and its predecessor court, the CCPA.

The problem may be that the MPEP does not sufficiently emphasize or exemplify the absolute nature of the inherency standard. The author recommends a revision of the MPEP 2112(IV), so as to emphasize the absolute nature of the standard.

Additional case law, such as application of Zierden, should be included to illustrate how absolute the standard is. And patent examiners should be made aware of the revision with a new guidance memo.

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Irving N. Feit is counsel at Lucas & Mercanti LLP. The opinions expressed are those of the author(s) and do not necessarily reflect the views of their employer, its clients, or Portfolio Media Inc., or any of its or their respective affiliates. This article is for general information purposes and is not intended to be and should not be taken as legal advice.

1. MPEP 2131, citing Verdegaal Bros. v. Union Oil Co. of California , 814 F.2d 628, 631 (Fed. Cir. 1987). ↩︎
2. MPEP 2131, citing Verdegaal Bros. v. Union Oil Co. of California , 814 F.2d 628, 631 (Fed. Cir. 1987). ↩︎
3. Application of Zierden, 411 F2d 1325 (CCPA 1969). ↩︎
4. Pharmacyclics LLC v. Alvogen, Inc, .Case 21-2270, Document 59 (2022). ↩︎
5. Hansgirg v. Kemmer , 102 F.2d 212 (C.C.P.A. 1939). ↩︎
6. In re Oelrich et al., 666 F.2d 578, 581 (CCPA 1981). ↩︎
7. Persion Pharmaceuticals v. Alvogen Malta Operations , 945 F.3d 1184, 1186 (Fed. Cir. 2019), rehearing denied (Feb. 28, 2020). ↩︎
8. Judge Rich is credited with having been the primary author of the U.S. patent laws in 1952. ↩︎
9. PAR Pharm. v. TWI Pharm. , 773 F.3d 1186 (Fed. Cir. 2014); Alcon Research v. Apotex , 687 F.3d 1362 (Fed. Cir. 2012); Schering Corp. v. Geneva Pharms. , 339 F. 3d 1373(Fed. Cir. 2003); Mehl/Biophile v. Milgraum , 192 F.3d 1362 (Fed. Cir. 1999); In re Napier , 55 F.3d 610 (Fed. Cir. 1995); In re King , 801 F.2d 1324 (Fed. Cir. 1986). ↩︎