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A Closer Look at the Post-Ariad Written Description Requirement

Intellectual Property Today
November 2012

Browning Ph.D., Paul W., Main Ph.D., Denise , DeRoo, Pier D.


Authored by Paul W. Browning, Ph.D.; Denise Main, Ph.D.; and Pier D. DeRoo

The decade preceding the Federal Circuit's en banc Ariad decision concerning the written description requirement brought multiple split opinions regarding its proper role under 35 U.S.C. § 112, first paragraph. See, e.g., Enzo Biochem, Inc. v. Gen-Probe Inc., 323 F.3d 956, 976 (Fed. Cir. 2002); Lizardtech, Inc. v. Earth Res. Mapping, Inc., 433 F.3d 1373, 1376 (Fed. Cir. 2006). According to the dissent in Enzo, this dispute began when the Lilly Court deviated from thirty years of precedent by applying the written description requirement outside of the context of priority disputes and as a general requirement for all patent claims, in addition to enablement. Enzo, 323 F.3dat979-980 (dissent) citing Regents of the University of California v. Eli Lilly & Co., 119 F.3d 1559 (Fed. Cir. 1997). The Enzo dissent lamented that "the aberrant form of [the written description requirement] requires far more specific disclosure than enablement" and thus, "defendants will have no need to invoke enablement, but will proceed directly to the more demanding § 112, ¶ 1 requirements." Enzo, 323 F.3d at 981-982 (dissent).

Before the Ariad Court, Ariad similarly argued that Lilly applied the written description requirement outside of the context of priority disputes, transforming it into a heightened and unpredictable general disclosure requirement. Ariad Pharmaceuticals, Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1349 (Fed. Cir. 2010). With its en banc decision, however, the majority in Ariad rejected Ariad's argument as well as Ariad's characterization of the written description requirement as a "super enablement" standard for chemical and biotechnology inventions, and reaffirmed the existence of a separate written description requirement in § 112 as well as the application of the written description requirement to original claims. Id. at 1349 ("[A]lthough the issue arises primarily in cases involving priority, Congress has not so limited [§ 112, ¶ 1], and neither will we."); id. at 1352.

More than two years since the Ariad decision, a significant number of Federal Circuit and district court decisions have addressed the written description requirement as a general patentability requirement, providing some preliminary data concerning how written description will be applied post-Ariad.

Is Written Description the Dominant Basis for § 112 Review?

An analysis of post-Ariad cases suggests that written description compliance is used more frequently as a general challenge to the validity of patent claims rather than to police priority of later-filed claims. Only seven of the Federal Circuit's twenty-two post-Ariad opinions involving written description concerned priority of later-filed claims. And when twenty-two post-Ariad written description opinions at the Federal Circuit are compared against just five enablement-related opinions, some might argue that written description is the dominant basis for § 112 review. See, e.g., Centocor Ortho Biotech, Inc. v. Abbott Labs., 636 F.3d 1341, 1344 (Fed. Cir. 2011) (reaching only written description issues for invalidating patent); Billups-Rothenberg v. Assoc. Regional & Univ. Pathologists, Inc., 642 F.3d 1031, 1037-38 (Fed. Cir. 2011).

Some might even take this a step further and argue that a written description challenge is the preferred defense among accused patent infringers because written description requires a higher standard than enablement. Identifying concrete evidence to support such a theory, however, is problematic at least for the reason that an accused infringer may assert a written description challenge simply to avoid conflicting enablement sufficiency/obviousness arguments. Adding to the mix of uncertainty, in some instances, the accused may assert both written description and enablement challenges while the court only addresses one.

Is There a Heightened Requirement for Written Description in the Chemical and Biotechnology Arts?

Similarly, some might argue that an analysis of post-Ariad cases supports Ariad's characterization of the written description requirement as a "super enablement" standard for chemical and biotechnology inventions. The post-Ariad Court has invalidated the claims of such patents under written description in four of six (66%) appeals. By comparison, the post-Ariad Court only found patent claims invalid in one of three appeals (33%) for each of the mechanical and the electrical/computer arts.

But these results may not tell the whole story given that the Federal Circuit's affirmance rate is over 70% in post-Ariad written description appeals, perhaps implicating a deference to district court decisions. To that end, an analysis of district courts' application of the written description requirement reveals that district courts have applied it more frequently to invalidate patent claims in the mechanical and electrical arts than in the chemical/biotechnology arts.1 The courts have invalidated patent claims in the mechanical arts most often, in four of fourteen cases (28%), and patent claims in the electrical/computer arts almost as often, in five of eighteen cases (27%). By comparison, district courts, notably, all within the third circuit, invalidated patent claims in the chemical/biotech arts in just three of nineteen cases (16%) nationwide. See Apotex Inc. v. Cephalon, Inc., No. 06-cv-2768, 2011 WL 6090696, at *24 (E.D. Pa. November 7, 2011); Alcon Research Ltd. v. Barr Labs. Inc., et al., 837 F.Supp.2d 364, 383-384 (D.N.J. 2011); Wyeth v. Abbott Labs., Nos. 08-cv-230, 08-cv-1021, 2012 WL 175023, at *10, 17 (D.N.J. January 19, 2012). And the Alcon and Wyeth courts additionally found the asserted claims invalid for lack of enablement. Alcon, 837 F.Supp.2d at 380-383; Wyeth, 2012 WL 175023 at *13, 18.

Given these trial court results and the Federal Circuit's arguable deference to trial courts' decisions, recent Federal Circuit jurisprudence cannot conclusively prove that written description requires a heightened and unpredictable general disclosure requirement in the chemical/biotech arts. Instead, mechanical and electrical arts seemingly appear equally susceptible to failing to satisfy written description, if not more so.

Strategies for Post-Ariad Compliance with the Written Description Requirement

Regardless of whether the written description requirement, post-Ariad, constitutes a "heightened" enablement standard, the Federal Circuit clarified that there is a separate written description requirement, and the practitioner must prepare patent applications to withstand written description challenges. Unfortunately, the boundaries for satisfying written description remain elusive because explicit guidance in written description jurisprudence, for the most part, focuses on that which is not required, rather than what is required. For example, the written description requirement does not necessarily require examples. Ariad, 598 F.3d at 1352. It does not necessarily require actual reduction to practice. Id.; Streck, Inc. v. Research & Diagnostic Sys., Inc., 665 F.3d 1269, 1285 (Fed. Cir. 2012). Written description compliance does not require any recitation of known structure. Falko-Gunter Falkner v. Inglis, 448 F.3d 1357, 1367 (Fed. Cir. 2006). Nor does it require any particular form of disclosure. Carnegie Mellon Univ. v. Hoffmann-La Roche Inc., 541 F.3d 1115, 1122 (Fed. Cir. 2008). Accordingly, positive guidance for written description compliance has often been lacking, even though § 112 demands a fairly exacting description of a claimed invention in the specification. Ariad, 598 F.3d at 1352 ("[A] description that merely renders the invention obvious does not satisfy the requirement.").

Since Ariad, however, court decisions suggest certain trends regarding when the written description requirement is satisfied, though compliance in any particular instance will necessarily depend on multiple factors. See Ariad, 598 F.3d at 1351. To that end, an analysis of key post-Ariad Federal Circuit cases involving written description is provided below with an eye towards devising strategies to guide practitioners for compliance with the written description requirement.

Describing Embodiments in the Alternative and Omitting Restrictive Language May Provide Broader Support

Probably the first and foremost strategy for surviving a written description validity attack is to draft the patent application broader than the scope of the claims to include multiple inventions or embodiments if applicable. If possible, such embodiments should be described in the alternative. Further, the applicant should refrain from using language within the specification, such as describing an embodiment as being imperative to the invention, where such language could be used to limit the scope of the claims. For instance, in a priority-policing case, the Federal Circuit found insufficient support in a digital imaging patent application disclosing only a "blue noise mask" for later-filed claims encompassing a "blue noise dot profile." Research Corp. Techs., Inc. v. Microsoft Corp., 627 F.3d 859, 871 (Fed. Cir. 2010). A "blue noise mask" differs from a "blue noise dot profile" in that not all dot profiles in the latter are limited to blue noise characteristics. Yet, the earlier "blue noise mask" application failed to mention any other dot profiles. The earlier "blue noise mask" application also repeatedly characterized the description of the "blue noise mask" as "the present invention," thus precluding inclusion of other inventions. Id. at 871-872. Accordingly, describing alternative embodiments of an invention, to the extent possible, while minimizing restrictive language may provide broader written description support.

This concept proved successful in a biotechnology case where the specification required a specific range of internodal distances for developing vascular grafts that would permit tissue in-growth. As an alternative embodiment, the specification identified a specific range of wall thicknesses that exhibited "excellent mechanical properties." Bard Peripheral Vascular, Inc. v. W.L. Gore & Assocs., Inc., 670 F.3d 1171, 1188 (Fed. Cir. 2012). Since the wall thickness was described in the alternative, the Court found this disclosure sufficient to support claims omitting any thickness limitation whatsoever, thereby permitting claims to grafts with thicknesses outside of the range described in the specification. Id. at 1188-1189; see also Crown Packaging Tech., Inc. v. Ball Metal Beverage Container Corp., 635 F.3d 1373, 1381-82 (Fed. Cir. 2011). Thus, describing elements in the alternative, rather than as imperative to the claimed invention, may provide broader support.

By comparison, in another example, the asserted claims survived a written description challenge notwithstanding that the specification fixated on application of the invention to a single device, a cathode ray tube display. Nevertheless, the Federal Circuit found this disclosure sufficient for claims incorporating other devices simply because the specification provided inclusive language that "[w]hile specific configurations of the local display . . . have been described, it is understood that the present invention can be applied to a wide variety of . . . devices." Honeywell Int'l, Inc. v. United States, 609 F.3d 1292, 1301 (Fed. Cir. 2010) (reversing invalidation on written description grounds). Here, the use of non-limiting language proved useful in surviving the written description validity challenge.

Knowledge of One of Ordinary Skill May Support Written Description Compliance

In addition to broad disclosures and non-limiting language, the applicant must also consider what aspects of the invention are known in the prior art. As seen in Honeywell above, prior art may help bridge gaps in disclosure, as written description compliance depends in part on the scope and content of the prior art, the maturity of the technical field, and the predictability of the technology at issue. Ariad, 598 F.3d at 1351. Accordingly, "in some instances, a patentee can rely on information that is 'well-known in the art' to satisfy written description." Streck, Inc. v. Research & Diagnostic Sys., Inc., 665 F.3d 1269, 1285 (Fed. Cir. 2012).

Consideration should be given, however, to whether such reliance on the prior art may invite obviousness-based validity challenges. Further, the applicant may be precluded from such reliance where the "four corners of the specification directly contradict information that the patentee alleges is 'well known' to a person of skill at the effective filing date ...." Streck, 665 F.3d at 1285. For example, emphasizing in the specification the uncertainty in the art or that the precise mechanism of a therapeutic ingredient "is still under active investigation" can preclude a patentee from relying on the prior art to bridge gaps in its disclosure. Boston Scientific Corp. v. Johnson & Johnson, 647 F.3d 1353, 1366-67 (Fed. Cir. 2011).

Strategies for Improving Written Description Support for Genus, Sub-Genus, and Species Claims

Patents reciting genus claims, however, typically do not have a wealth of prior art to use in bridging disclosure gaps, and have therefore proven particularly susceptible to invalidity for inadequate written description. See, e.g., Carnegie Mellon, 541 F.3d at 1125-27; but see Capon v. Eshhar, 418 F.3d 1349, 1358 (Fed. Cir. 2005) (where prior art contained "extensive knowledge of the nucleotide structure," including hundreds of identified DNA chains).

When broad claims cannot rely on prior art, the Federal Circuit has clarified that a patent should disclose either "structural features common to the members of the genus" or "a representative number of species" within the genus. Ariad, 595 F.3d at 1350. Indeed, the Federal Circuit has long recognized that describing only a single species typically fails to provide adequate written description. See, e.g., Ariad, 598 F.3d at 1354-55; Capon, 418 F.3d at 1358-59; Boston Sci., 647 F.3d at 1365; Billups-Rothenberg, 642 F.3d at 1037. In that vein, the Court's jurisprudence has illustrated that the "representative number of species" route, when possible, may be safest. For example, in Boston Scientific, although the "[rapamycin] technology was still in its infancy" as of the filing date, the patentee had disclosed information regarding a broad genus of rapamycin analogs. 647 F.3d at 1367. But the claims were directed to a sub-genus of "macrocyclic triene" analogs, which the disclosure did not specifically describe in any manner. Id. Without any information in the prior art that may have directed a person of ordinary skill to the sub-genus, the Court found the specification inadequate to describe the claimed sub-genus, even though the described genus necessarily did describe, at a higher level, the sub-genus. Id. at 1367-68.

Similarly, describing a genus or a sub-genus may fail to adequately describe a claimed species. Id. at 1367. Thus, current jurisprudence counsels an applicant to take care in adequately describing a common structure or feature for each level of claim: genus, sub-genus, and species. This may require exhaustive disclosure.

To avoid potential problems, describing several alternative common features, or a range of alternative representative species, may help support written description compliance. For example, a practitioner might use certain species or features to support one sub-genus claim, while using another selection of species or features to support a different claim. Thus, disclosing alternative features or species, in a manner similar to that discussed above, may help provide broader written description support than relying on a single feature essential to the claimed invention. See Bard, 670 F.3d at 1188-89. Indeed, the more species identified to support a genus improves the chances for surviving written description challenges.


With its en banc decision, the majority in Ariad reaffirmed the existence of a separate written description requirement in § 112 and its application to original claims. Thus, practitioners must continue to prepare patent applications with an eye towards prevailing against written description challenges. Whether or not written description challenges target one technical field over another, a careful analysis of ensuing Federal Circuit decisions across all fields should continue to further guide practitioners in devising strategies for written description compliance, as trends in the fact-specific written description analysis continue to coalesce.

1 The authors reviewed post-Ariad Federal Circuit and district court opinions through August 16, 2012 applying written description as a general disclosure requirement, not as a priority policing requirement.

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