Enablement – Did the public receive all it contracted to receive?

patent-word-jumbleA patent is a type of contract under which the patentee is given a temporary monopoly in exchange for disclosing the invention to the public. The public can freely use the invention after the monopoly period and can improve upon or design around the invention during the monopoly period. Under this contract, the patentee has the obligation to enable the invention, i.e., the disclosure of the patent must contain information that is sufficient to inform those skilled in the relevant art how to both make and use the claimed invention. “The public yields nothing which it has not agreed to yield; it receives all which it has contracted to receive.” Grant v. Raymond, 31 U.S. 218, 241-42 (1832). A claim drafted too broadly may not be enabled and hence be invalid. Yet, the temptation to claim broadly often leads the patentee to ignore this risk. Most are familiar with the example of Samuel Morse, the inventor of the telegraph, who in one of the claims in his patent claimed not just the telegraph, the invention described in the specification, but all means of communicating electronically at a distance (which would have covered as yet undiscovered technologies, such as radio and television). This article uses a 2014 Federal Circuit opinion and 19th century US Supreme Court cases to provide a context for the enablement requirement and for the standard for determining if the requirement has been met.

Overly broad claims may deter innovation and are a disservice to the society. A great example of how this might happen can be found in a case that dealt with the alleged infringement by the manufacturer of Edison’s incandescent electric lamp of a patent held by Sawyer and Man. Consolidated Electric Light Co. v. McKeesport Light Co. 159 U.S. 465 (1895). Sawyer and Man had discovered the use of carbonized paper for incandescent lamps. The specification of the patent described use of carbonized paper and wood carbon (i.e., exogenous vegetable growth). However, while one claim was directed to an incandescing conductor made of carbonized paper, the remaining claims were directed to an incandescing conductor made of carbonized fibrous or textile material– not carbonized paper. Edison, on the other hand, had discovered that a particular part of the stem of a bamboo, lying directly beneath the siliceous cuticle, had properties that made it suitable to function as an incandescing conductor. In this part of the stem, the fibers were nearly parallel, cell walls smallest in dimension, and the pithy matter between the fibers minimal. Also, Edison apparently had found that incandescing carbon filaments that worked could not be made of wood because the fibers were not parallel, and the longitudinal fibers were intercepted by radial fibers. The commercial Edison lamp, accordingly, had a burner made of special carbonized bamboo. The carbonized bamboo, being encompassed by the carbonized fibrous or textile material of Sawyer and Man’s patent claims, the lamp was alleged to be infringing. The US Supreme Court observed that if Sawyer and Man had discovered in fibrous and textile substances a quality common to them all, as distinguishing them from other materials, such as minerals, etc., the claims might not be too broad. Since that was not the case, as evident from an examination of over 6,000 vegetable growths which did not result in any that possessed the peculiar qualities that allowed them to function as incandescing conductor for an electric lamp, the Court asked “[w]as everybody, then, precluded by this broad claim [to carbonized fibrous or textile material] from making further investigation? The Court thought not.

Sometimes, despite the scrutiny of the Examiner at the USPTO, claims that are not enabled pass muster with the office, and with a district court judge, and are invalidated only by the Federal Circuit on appeal. This scenario was recently played out in Promega Corp. v. Life Technologies Corp. (Fed. Cir. 2014) (hereinafter “Promega v. Life Tech.”). The opinion illustrates how, in such situations, the ordinarily skilled person is unable to fill the technical gaps in the disclosure, and is therefore not put in a position to make and use the full scope of the invention. The opinion reminds the reader that enablement functions to ensure that public knowledge is enriched by the patent specification to a degree at least commensurate with the scope of the claims, which is possible only when the scope of the claims is less than or equal to the scope of enablement.

The enablement requirement is set forth in 35 U.S.C. § 112(a) or 35 U.S.C. § 112, ¶ 1 (pre AIA) as follows:

The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention. [emphasis added]

Although § 112 originates from the Patent Act of 1952, the requirement has been a part of the patent law since the first patent statute of 1790. Act of April 10, 1790, ch. 7, § 2, 1 Stat. 109, 110.

The statute has been interpreted to require that to be enabled an ordinarily skilled person should be able to make and use the invention without “undue experimentation.” In re Wands, 858 F.2d at 737, 8 USPQ2d at 1404 (Fed. Cir. 1988). The Manual of Patent Examining Procedure (M.P.E.P.) describes this standard as being cast in the U.S. Supreme Court decision of Mineral Separation v. Hyde, 242 U.S. 261, 270 (1916). M.P.E.P. § 2164.01. Interestingly, the phrase “undue experimentation” appears nowhere in Minerals. One may therefore ask: what did the Court say in Minerals that could be summed up in this phrase? The invention in Minerals was directed to a method of concentrating ores by using a combination of air bubbles and oil, with oil used in very small quantities, enough to coat particles of metal with a thin film, and the lifting force that was generated being the result not only of the natural buoyancy of the added oil, but largely that of the buoyancy of the air bubbles. The challenger argued that the patent was invalid because each ore would require preliminary tests to determine the amount of oil and the extent of agitation necessary. The Court disagreed, stating that although the range of treatment within the terms of the claims left something to the skill of persons applying the invention it was clearly sufficiently definite to guide those skilled in the art to its successful application. As we shall see below, guidance for those skilled in the art is one of the key parameters for determining undue experimentation.


The enablement issue in Promega v. Life Tech. was related to genus claims encompassing a large number of species. In general, the specification need not describe how to make and use each possible variant or species of a claimed invention if knowledge of the skilled artisan and routine experimentation can fill the gaps. AK Steel Corp. v. Sollac, 344 F.3d 1234, 1244 (Fed. Cir.2003). That is, the skilled artisan, without undue experimentation, should be able to determine which covered species would work as claimed. Promega asserted a number of patents against Life Tech. In response Life Tech. argued that the claims in the patents were invalid for reasons including lack of enablement. Siding with Promega the district court ruled that the claims were enabled. Life Tech. contested the district court ruling and the Federal Circuit agreed with Life Tech. Interestingly, what seemed to throw the district court off were the so called “unrecited elements.” The Court’s analysis of unrecited elements is discussed later in the article.

The claims at issue in this case were related to multiplex amplification of STR (short tandem repeat) loci in DNA. An STR locus consists of several repeats of a specific sequence of DNA. A large number of STR loci are spread across a genome. Among different persons, the number of times a sequence is repeated within an STR locus differs, giving rise to the possibility of a type of DNA fingerprinting called “STR profiling,” which is useful in many areas, including Forensics and Human Identity.

STR profiling involves generating multiple copies of the loci of interest in a single reaction. This is achieved by an amplification process called polymerase chain reaction (PCR), in which several pairs of “primers” are used, each pair associating at the flanks of a specific STR locus, allowing a DNA polymerase to replicate the DNA between the flanks. The cycle of replication is repeated until sufficient DNA is obtained for analysis. Simultaneous amplification of multiple STR loci i.e., “multiplexing”, is highly desirable. However, multiplexing is complex, and successful co-amplification depends on the choice of a set of primer pairs such that any given primer pair associates only at the flanks of the target locus and does not interfere with other primer pairs for associating with their target loci. Whether a given set of loci would successfully co-amplify could not be predicted at the time of the invention. Also, it was known that as the number of STR loci sought to be amplified in a single reaction was increased, the odds of obtaining successful multiplexing decreased. Without a teaching, scientists could not predict with any certainty whether a given set of loci would successfully co-amplify even when only one new locus was added to an already successful multiplex since skilled artisans could not predict how the loci would interact with each other or how effectively and efficiently the primers would work in a single reaction [multiplex] environment.

Claim 23 (U.S. Patent No. 6,221,598), set forth below is representative of claims in the patents-in-suit:

“A kit for simultaneously analyzing short tandem repeat sequences in a set of short tandem repeat loci from one or more DNA samples, comprising:

a single container containing oligonucleotide primers for each locus in a set of short tandem repeat loci which can be co-amplified, comprising HUMCSF1PO, HUMTPOX, and HUMTH01.” [emphasis added]

The district court construed claims that used the transition phrase “comprising” for modifying a combination of STR loci as not being limited to the recited STRs, i.e., as allowing for unrecited loci. Such claims were referred to as the “open loci set” claims. Accordingly, in addition to the recited three-plex co-amplification, the representative claim above would encompass any other larger, more complex multiplex reaction so long the three recited loci were included.

Promega characterized the unrecited STR loci combinations in the “open loci set” claims as merely “unrecited elements” (and therefore outside of claim scope and not subject to the enablement requirement). To the contrary, the Federal Circuit regarded the same elements to be part of the claim scope, and subject to the enablement requirement.

Upon reviewing the technology involved in the “open loci set” claims, the court concluded that co-amplifying STR loci multiplexes was complex, and successful identification of a co-amplifying multiplex that adds even a single new locus to an existing loci combination was unpredictable. The unpredictability arose from significant alteration of the chemistry of a multiplex reaction due to inclusion of the new locus. Therefore, given the state of technology, claim to any multiplexing that was not shown in the specification to have been carried out successfully was not enabled. The court plainly observed that Promega had chosen broad claim language “at the peril of losing any claim that cannot be enabled across its full scope of coverage.”

The court provided examples of recent cases where the patentee had similarly chosen breadth over enablement. In one case, Wyeth & Cordis Corp. v. Abbott Labs., 720 F.3d 1380 (Fed. Cir. 2013), the claims covered a broad class of drug compounds with certain structures and properties. While the specification disclosed only one species of the compound with the particular characteristics, the patentee nevertheless argued that the claims encompassed tens of thousands of other species within the genus that were not disclosed by the patent. It was undisputed that a skilled artisan could not determine whether a particular compound would exhibit the claimed properties without going through the laborious and iterative process of synthesizing and screening that compound. The court noted that the specification was silent as to how one might modify the disclosed compound in a way that would preserve the recited utility. The claims were held invalid since undue experimentation would have been required to practice the full scope of the claims.

The court observed that as in Wyeth, Promega’s claims covered potentially thousands of undisclosed embodiments in an unpredictable field with the specification providing no guidance as to how, absent laborious testing, a skilled artisan might add new loci to the recited STR loci combinations that would still successfully co-amplify. Therefore, the open loci set claims could not be valid.

The opinion also addressed the use of the open ended “comprising” in the preamble versus its use in a specific limitation, pointing out that there is a difference between the two uses. When used in the preamble of a claim, “comprising” permits the inclusion of other steps, elements, or materials in addition to the elements or components specified in the claims. Citing a past opinion related to a device claim, the court stated that open claims, “embrace technology that may add features to devices otherwise within the claim definition.” The court added, “[w]hile the term “comprising” in a claim preamble may create a presumption that a list of claim elements is nonexclusive, it “does not reach into each [limitation] to render every word and phrase therein open-ended.” Because the relevant usage of “comprising” by Promega was with respect to the “open loci set” limitation (not the preamble), it covered what indisputably were advances in this unpredictable art. Therefore, the court explained, the numerous embodiments covered by Promega’s claims could not be regarded as merely “unrecited elements” in a standard “open-ended” claim.

At what stage, one might ask, does experimentation becomes undue? Citing earlier opinions the court clarified that undue experimentation was a matter of degree, and even a considerable amount of experimentation was permissible, so long as it was merely routine, or the specification provided a reasonable amount of guidance regarding the direction of experimentation. However, the court also cautioned that permissible routine experimentation was not without bounds. Thus, the application of the undue experimentation standard requires a balance. Too relaxed an application, under which even a very large amount of experimentation would not be undue, would increase the possibility that an ordinarily skilled artisan would be unable to make and use the invention. On the other hand a very strict requirement for enablement entails the risk of discouraging inventors from filing patent applications in an unpredictable area since the claims would have to be limited to those embodiments which are expressly disclosed. In re Angstadt, 537 F.2d 498, 503 (Cust. & Pat.App.1976). Such inventions could be easily circumvented without inventive effort, leading inventors to resort to trade secrets, and the resultant loss of the benefits of a public disclosure.

The Author

Sanjeev Mahanta, Ph.D., J.D.

Sanjeev Mahanta, Ph.D., J.D. is an attorney in the Patent group of Arent Fox, LLP. Sanjeev’s practice focuses on prosecution of domestic and international patent applications. Sanjeev helps clients obtain patents across a wide technology spectrum including biotechnology, pharmaceuticals, chemistry, materials science, and medical device.

For more information or to contact Sanjeev, please visit his Firm Profile Page.

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Discuss this

There are currently 3 Comments comments.

  1. Anon March 7, 2015 7:53 pm

    I like the phrase: “The particularity and certainty of disclosure which the law requires in patents is not greater than is reasonable, having regard to their subject-matter.

    242 U.S. 261 (1916)

  2. Ken March 8, 2015 10:59 am

    The problem IMO is the tension between requiring “full scope” enablement and the classic principle that a patent can cover later-arising improved versions of the patented invention (though such improvements themselves can be patented separately as well, hence the notion of patents being only a “negative right”).

    Have we ever gotten decent guidance from the courts about how to reconcile this?

  3. Anon March 8, 2015 2:16 pm


    I echo your note of tension, but would point out that for improved versions to earn patents separately, there is indeed a bar that must be crossed and this bar does in fact separates that which (while still later-arising) would be (potentially under the doctrine of equivalents) covered by an earlier patent.

    Some guidance, while admittedly a bit cryptic, can be seen in the Supreme Court KSR case:

    Granting patent protection to advances that would occur in the ordinary course without real innovation retards progress and may, for patents combining previously known elements, deprive prior inventions of their value or utility.” (emphasis added) 550 US 398 at 405.

    I do not think that your application of the concept of a patent as a negative right is quite on the money as to the point you are attempting to make. Improvements may or may not fall within the scope of equivalents, and also may or may not be obvious (i.e., may or may not be patentable). Each of these variants does not control the fact that an improvement patent itself (one clearly rising to the level of being patentable) but necessarily involving a portion still under the control of a patent (ostensibly of another) is not free to be practiced by the holder of the improvement patent. That sense of “negative right” is distinct from the concept here of what is the scope of protection for the initial patent as to non-colorable changes.

    I think it extremely important to be able to keep these distinctions firmly established in the mind when discussing these issues.