Print PDF


Unpredictability: Understanding the U.S. Enablement Requirement

CIPA Journal
March 2012

Bosch, Michele C., Main Ph.D., Denise


Authored by Michele C. Bosch and Denise Main, Ph.D.


Both the Boards of Appeal of the European Patent Office (EPO) and the U.S. Court of Appeals for the Federal Circuit, which hears appeals from the United States Patent and Trademark Office (USPTO) as well as from U.S. district courts, have struggled for at least the last two decades to identify the demarcation line between when an application or a patent contains sufficient disclosure of an invention for a skilled person to practice that claimed invention and when they do not. This challenge garners little instruction from the generalized language of the respective statutes governing this issue on both sides of the ocean. Indeed, the statutory language of the two jurisdictions is strikingly similar in both the guidance provided and the lack thereof. Since the USPTO must ultimately carry out the patent laws of the United States as articulated by the Federal Circuit, this article will focus on the decisions of the Federal Circuit to provide patent practitioners with the most current and comprehensive guidance regarding the enablement standards and compare these standards to that of the EPO. The article will look at the question: How much is enough and can satisfying these standards be predicted with certainty?

The Familiar Sufficiency Standard of the EPO

Article 83 of the European Patent Convention provides the governing law of the EPO and simply states "the European patent application shall disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art." The EPO Boards of Appeal have attempted to elucidate this provision, and provide guidelines for the patent practitioner to follow. For instance, in view of the specification and a skilled person's common knowledge, the skilled person must be able to practice the full scope of the claims "without undue burden."1 The question of whether a person skilled in the art could practice the claimed invention without undue burden, however, especially in unpredictable fields such as the biotechnology arts, cannot be easily answered and is determined on a case-by-case basis.

That being said, sometimes including a single example of how to carry out the invention claimed in a patent application may suffice to render it apparent to the skilled person how to practice the invention.2 But, where the claims cover a broad scope, it may be necessary for the description to include a number of examples or alternative embodiments of the invention to satisfy this requirement. Indeed, Article 83 is not satisfied "if technical information crucial for carrying out the invention is missing [from] the application as a whole."3 Illustrating these differing views, there are a number of decisions of the EPO Boards of Appeal where disclosing or exemplifying "one way" to practice the claimed invention was deemed sufficient, and another set of cases where the "one way" disclosed was simply not enough. Seeking to follow the guidance provided by these various EPO cases to satisfy the sufficiency of disclosure requirement is akin to seeking a moving target.

The Similar U.S. Enablement Requirement

The same divergence of guidance is found in the United States where the governing statute, 35 U.S.C. §112, first paragraph, is equally ambiguous, requiring disclosure of "the manner and process of making and using [the invention], in such full, clear, concise, and exact terms as to enable any person skilled in the art . . . to make and use [the invention]." Similar to that which is required by the EPO, the U.S. law provides that the disclosure of a U.S. patent application or issued patent must teach those skilled in the art how to make and use the full scope of the claimed invention without "undue experimentation."4 The Federal Circuit has explained that while a disclosure must enable one of ordinary skill in the art to practice the full scope of the invention, "[t]hat is not to say that the specification itself must necessarily describe how to make and use every possible variant of the claimed invention, for the artisan's knowledge of the prior art and routine experimentation can often fill gaps, interpolate between embodiments, and perhaps even extrapolate beyond the disclosed embodiments, depending upon the predictability of the art."5

Satisfying the enablement requirement articulated by U.S. statute and explained by U.S. case law is equally difficult before the USPTO as the analogous effort is before the EPO because, just like the Boards of Appeal for the EPO, the Federal Circuit has provided two seemingly distinct lines of decisions, exemplifying the analogous struggle with this issue that exists on the other side of the ocean. In one line of cases, disclosure of a single example of making and using the claimed invention is deemed sufficient for enabling the skilled person to practice the scope of the claimed inventions without undue experimentation. As discussed below, these cases are not confined to the predictable arts. The other line of cases, however, seems to require a range of examples to enable the full scope of the inventions, which are in traditionally predictable, as well as unpredictable fields. This article provides a brief overview of select decisions rendered by the Federal Circuit that highlight the similarity of divergent guidance that is provided to patent practitioners in the U.S. as exists in practicing before the EPO. The article further provides strategic considerations for successfully drafting a single patent application for filing in the European and U.S. patent offices that seek to improve one's chances for satisfying the EPO requirement for sufficiency of disclosure and the similarly complex U.S. enablement requirement.

Disclosure of a Single Embodiment Is Enabling

With respect to the "single embodiment" line of cases, the Federal Circuit initially appeared to limit when the enablement requirement could be satisfied through the disclosure of a single embodiment to what some practitioners may consider predictable arts, such as the mechanical or electrical arts. In 1987, the Federal Circuit in Spectra-Physics, Inc. v. Coherent, Inc. held that "[i]f an invention pertains to an art where the results are predictable, e.g., mechanical as opposed to chemical arts, a broad claim can be enabled by disclosure of a single embodiment, and is not invalid for lack of enablement simply because it reads on another embodiment of the invention which is inadequately disclosed."6

In a subsequent mechanical case, Engel Industries, Inc. v. Lockformer Co., the asserted claims were directed to a method for connecting the ends of sheet metal ducts.7 The Federal Circuit rejected the lack of enablement argument for failure to disclose a method of crimping the ducts together, relying on precedent that "failure to include operating conditions known in the art cannot rise to rejection under the enabling or best mode requirements of §112."8 In addition, the Court provided a guideline for enablement similar to that found in Spectra-Physics, finding that "[t]he enablement requirement is met if the description enables any mode of making and using the claimed invention."9 Unlike Spectra-Physics, however, the Engel Court's application of this level of enablement contained no language limiting its application to the predictable arts.

Numerous cases over the years that fall within predictable or unpredictable arts, including mechanical and biotechnology-related cases, have relied upon this holding in Engel that "any mode of making and using the claimed invention" is sufficient to satisfy the enablement requirement. Two such cases, CFMT and Johns Hopkins, are straight-forward "single embodiment" cases,10 and contain no discussion of predictability or level of knowledge in the art to fill in any perceived gaps in disclosure. Rather, the enablement requirement was satisfied simply because the specification included a single method of making and using the claimed invention.11 Notably, the Court in Johns Hopkins stated that the burden of showing lack of enablement could be met by demonstrating that all of the alternative embodiments disclosed were not enabled because "the enablement requirement is met if the description enables any mode of making and using the invention."12 This holding seems to suggest that the patent challenger asserting lack of enablement bears a high burden in that they must demonstrate that all, not just some, embodiments falling within the scope of the claims are not enabled.

In 2003, the biotechnology case Amgen Inc. v. Hoechst Marion Roussel involved claims construed more broadly than the example disclosed in the patent. Here, in finding the claims enabled, the Amgen Court looked not only to the disclosure providing the prerequisite method of making and using the invention, but also relied on what was known in the art to fill in any gaps in the disclosure. In addition, post-filing evidence further demonstrated an enabling disclosure as of the time of filing. Thus, under Amgen, it would appear that the requirements for enabling claims in the unpredictable arts has evolved such that more than just simply providing enablement for a single embodiment may be required.

Another biotechnology case, Invitrogen Corp. v. Clontech Labs, Inc., involved claims directed to a genetically modified enzyme without regard for a method of making the mutant enzyme.13 The Federal Circuit rejected the lack of enablement argument that certain methods for making the mutant enzyme were not disclosed, finding that those skilled in the art knew several techniques for altering genetic sequences.14 Further, the Court quoted the language in Engel that the "the enablement requirement is met if the description enables any mode of making and using the invention."15 The Court explained that "[e]nablement does not require the inventor to foresee every means of implementing an invention at pains of losing his patent franchise. Were it otherwise, claimed inventions would not include improved modes of practicing those inventions. Such narrow patent rights would rapidly become worthless as new modes of practicing the invention developed, and the inventor would lose the benefit of the patent bargain." Like Amgen, the Invitrogen Court found enablement based not only on the disclosure of any mode of making and using the invention but also on the knowledge of one skilled in the art. In addition, the Invitrogen Court warned against the dangers of narrowing the patentee's rights, clarifying that enablement does not require disclosure of every permutation falling within the scope of the invention.

The 2012 biotechnology case, Streck, Inc. v. Research & Diagnostic Systems, Inc., is the most recent Federal Circuit case where disclosure of a single embodiment was found to satisfy the U.S. enablement requirement.16 In Streck, the claims were construed more broadly than the example disclosed. Finding the claims enabled, the Court held that testimony concerning complications in practicing the invention prior to the disclosure of the invention was not evidence of nonenablement, finding "no undue experimentation would be necessary once the teachings in the patents-in-suit were known."17 Here, the Court again relied on the disclosure of a single embodiment but disregarded the lack of knowledge of one of ordinary skill in being able to practice the full scope of the claimed invention. Instead, the Court found the full scope of the invention could be practiced by simply following the teachings within the patent.

Disclosure of a Single Embodiment Is Not Enabling

In a parallel set of cases, the Federal Circuit has found a lack of enablement where the disclosure failed to provide sufficient embodiments demonstrating how to make and use the full scope of the claimed invention. A number of these cases interestingly involve technical fields that some may consider predictable. For instance, the 2007 mechanical/electrical case Automotive Technologies International, Inc. v. BMW of North America, Inc. involved a side-impact crash sensor for automobile airbags.18 The claims here were construed more broadly than the example disclosed. The Court found that practicing the full scope of the claimed invention would require undue experimentation, explaining that knowledge of one skilled in the art could not supply the missing information because the specification, not the knowledge of those skilled in the art, must supply novel aspects of the invention.19 This decision arguably stands in stark contrast to the "single embodiment" line of cases where the knowledge of one of ordinary skill can be used to fill any perceived deficiencies in the disclosure.

During the same year as Automotive, in another mechanical case Liebel-Flarsheim Co. v. Medrad, Inc., the claims were construed to include the embodiment disclosed by the example in the specification and also an alternative embodiment.20 Statements in the specification, however, taught away from the alternative embodiment and testimonial evidence revealed that the alternative embodiment could not have been produced at the time of filing.21 In view of this evidence, the Court found the claims not enabled because there was no guidance in the specification of how to make or use the alternative embodiment. A similar holding is found in the 2008 digital media case, Sitrick v. Dreamworks, LLC, where the Court explained that "a patentee who chooses broad claim language must make sure the broad claims are fully enabled."22 Here, the claims were construed to include both movies and video games. The Court found, however, that, based on expert testimony, the defendants "showed with clear and convincing evidence that one skilled in the art could not take the disclosure in the specification with respect to substitution or integration of user images in video games and substitute a user image for a pre-existing character image in movies without undue experimentation."23 Thus, while Automotive, Liebel and Sitrick are related to what some consider predictable arts, all three decisions could be interpreted to require disclosure of a method of making and using the full range of embodiments falling within the scope of the claimed invention.

Turning to certain biotech cases, i.e., a less predictable art, the Court seems to follow this same seemingly stringent requirement for enablement. In the 2004 Chiron Corp. v Genentech, Inc. case, the Court found the asserted claims invalid because the scope of the claim included two different antibodies, yet the disclosure fell short of providing a "specific and useful teaching" of all antibodies within the scope of the claim.24 According to the Court, certain of these antibodies only first appeared as a successful technology in the literature after the filing date of the application, showing the new technology arose after the filing date.25 According to the Court, "[t]he law requires an enabling disclosure for nascent technology because a person of ordinary skill in the art has little or no knowledge independent from the patentee's instruction. Thus, the public's end of the bargain struck by the patent system is a full enabling disclosure of the claimed technology." Similarly, in Monsanto v Syngenta, the asserted claim was construed to require the claimed gene to function in any plant cell, including both dicots and monocots.26 Transformation of monocots was not known in the art until after the filing date, and thus, the Court found that such transformation would require undue experimentation. Like the predictable art-related cases Automotive, Liebel and Sitrick, these two cases related to the unpredictable arts seem to require examples of making and using the full range of embodiments falling within the scope of the claimed invention to satisfy the enablement requirement.

Strategic Considerations for Satisfying the U.S. Enablement Requirement

As illustrated from this selection of Federal Circuit cases, U.S. case law concerning enablement provides the patent practitioner little if any clear guidance as to when and how detailed a disclosed method of making and using the claimed invention needs to be to satisfy the requirements of an enabling disclosure—a plight similar to that found in practicing before the EPO Boards of Appeal. In some instances, the disclosure of a single example is enough without regard to the predictability of the field; in other instances, a single embodiment is sufficient to enable the invention only where the knowledge of one skilled in the art can fill in the gaps in the disclosure found in the specification to practice the full scope of the claimed invention. If such gaps cannot be filled by knowledge generally known in the art, the disclosure likely will need to include a range of embodiments to enable the full scope of the claims. Despite the ability to identify the concerns with the existing guidance, it is uncertain whether the Federal Circuit will offer more clarity to the U.S. patent practitioner concerning this issue in the near future.

Further complicating matters is that a patent application may pass the enablement requirement upon examination and appellate review by the USPTO, which may grant a patent, but ultimately that patent may be challenged and invalidated by the arguably more stringent or ever-evolving standard applied in the district courts and by the Federal Circuit. Given this ambiguity, it is safer to err on the side of including multiple examples and alternative embodiments that can be used to unquestionably enable practice of the full scope of the claimed invention. In particular, where the claims are of a broad, generic scope that could be broken in to subgroups or subgenera that have identifiable distinctions, those distinctions should be recognized and addressed when evaluating the enablement inquiry as a practitioner. For example, in Monsanto, at least some claims may have withstood the enablement requirement had there been separate claims to different species of plant cells rather than just a claim directed to the genus of plant cells.

The practitioner should be careful to analyze the existing art in the related field, assessing the level of guidance the art reasonably would afford one skilled in the art. This assessment should be made when determining the scope of the claims. Any novel aspects of the claims devoted to new or nascent technology must be aptly supported with proper guidance or examples to support their scope. Such an analysis can be even more helpful and is likely to be necessary in unpredictable fields or where the point of patentability defines the invention.

Another advisable way for the practitioner to ensure the likelihood of satisfying the enablement requirement is to carefully consider how to describe and claim the invention in as many ways as possible before filing. This would include evaluating whether to include genus, sub-genus and species claims of varying scopes where sub-genus and species claims are included to ensure that the entire patent does not go down in flames should the court find the scope of the genus claims too broad to be sufficiently enabled by the disclosure. If varying scopes of disclosure and claims are considered during the drafting stage, the enablement requirement is more likely to be satisfied as the boundaries of the invention vis-à-vis the prior art and the level of skill and knowledge in the prior art will already have been considered.

Other Strategic Considerations for Practitioners Pursuing European and U.S. Patents

While satisfying the enablement requirement in the U.S. and the sufficiency of disclosure requirement at the EPO may require similar tactics when drafting a patent application, there are, of course, other distinguishing features between the patentability requirements of European and U.S. patent applications. For example, a U.S. patent application may incorporate by reference extrinsic evidence supporting the claimed invention. European patent applications cannot, or at least, it is heavily frowned upon. Another example is that U.S. applications must include the best mode for carrying out the claimed invention, notwithstanding that failure to disclose the best mode is no longer available as a defense in patent litigations in the U.S. for actions filed on or after September 16, 2011, per the newly enacted American Invents Act. Thus, when drafting a patent application that can be filed with both the EPO and the USPTO, one would need to address these and other distinguishing features between the patentability requirements of European and U.S. patent applications.


The divergence of guidance found in both U.S. case law concerning enablement and the EPO concerning sufficiency of disclosure may seem daunting. Nevertheless, strategic and careful drafting of a patent application is the best method for satisfying the enablement requirement and securing patentability. This involves understanding the level of knowledge available in the prior art, determining where that knowledge may fill any gaps in the disclosure, providing numerous examples of varying scope for practicing the claimed invention, and drafting claims of broad genus, sub-genus and species claims of varying scope. Such a strategy should afford satisfaction of the requirements of both sides of the ocean and place a patent practitioner in an advantageous position to ensure patentability. In other words, the only thing predictable about the enablement standard in the U.S. and the sufficiency of disclosure standard at the EPO is that more is always better.


1 Hitachi, Ltd. v. DaimlerChrysler AG, No. T 0063/06 at 7, (EPO Bd. App. June 24, 2008).

2 Haemonetics Corp. v. CaridianBCT, Inc., No. T 1610/08 at 9, (EPO Bd. App. September 21, 2011).

3 Hitachi, Ltd., et al., No. T 0561/96 at 9, (EPO Bd. App. January 16, 1997).

4 In re Wright, 999 F.2d 1557, 1561 (Fed. Cir. 1993) (citations omitted).

5 AK Steel Corp. v. Sollac, 344 F.3d 1234, 1244 (Fed.Cir. 2003).

6 827 F.2d 1524, 1533 (Fed. Cir. 1987).

7 946 F.2d 1528, 1530, 1533 (Fed. Cir. 1991).

8 Id. at 1532 (citations omitted).

9 Id. at 1533.

10 CFMT, Inc. v. Yieldup Int'l. Corp., 349 F.3d 1333, 1338-1339 (Fed. Cir. 2003) (claims to "removal of contaminants" in method for cleaning semi-conductors did not require a disclosure demonstrating "removal of all contaminants"); Johns Hopkins Univ. v. CellPro, Inc., 152 F.3d 1342, 1359-61 (Fed. Cir. 1998) (disclosure of producing the anti-My-10 antibody sufficient to enable the broader genus of claimed antibodies).

11 See CFMT, 349 F.3d at 1338; Johns Hopkins, 152 F.3d at 1361.

12 152 F.3d at 1361.

13 429 F.3d 1052, 1058, 1070 (Fed. Cir. 2005)

14 Id. at 1070.

15 Id. at 1071.

16 No. 11-1044 (Fed. Cir. Jan. 10, 2012).

17 Id. at *29-38 (emphasis added).

18 501 F.3d 1274, 1276-1277 (Fed. Cir. 2007).

19 Id. at 1283.

20 481 F.3d 1371, 1380 (Fed. Cir. 2007).

21 Id. at 1379-1380.

22 516 F.3d 993, 999 (Fed. Cir. 2008).

23 Id. at 1000.

24 363 F.3d 1247, 1254-1256 (Fed. Cir. 2004).

25 Id. at 1254.

26 503 F.3d 1352, 1361 (Fed. Cir. 2007).

Originally printed in CIPA Journal. This article is for informational purposes, is not intended to constitute legal advice, and may be considered advertising under applicable state laws. This article is only the opinion of the authors and is not attributable to Finnegan, Henderson, Farabow, Garrett & Dunner, LLP, or the firm's clients.