United States: Patent Coverage Of Impossible Embodiments: A Cautionary Tale For Patent Owners, And Lingering Questions

Last Updated: July 25 2019
Article by Scott I. Forman and Charles T. Steenburg

Patent owners asserting their patents in litigation will often seek broad claim constructions to cover accused products and forestall defendants' non-infringement defenses. However, a recent decision illustrates potential pitfalls of this strategy even aside from traditional concerns about reading claims so broadly as to cover prior art.

In Trustees of Boston University v. Everlight Electronics Co., 896 F.3d 1357 (Fed. Cir. 2018), the U.S. Court of Appeals for the Federal Circuit invalidated a patent claim to a semiconductor device based on a claim construction that the patent owner proposed. The construction covered six permutations for the composition of the device, one of which was indisputably impossible to make using the method taught in the patent. A patent must be enabling, such that it teaches one of skill in the art to make and use the full scope of the claimed invention without undue experimentation. The court found the claim was not enabled because it encompassed the unattainable permutation. This case demonstrates that patent owners must be careful not to propose a claim construction so broad as to cover embodiments not enabled by the patent disclosure. However, the exact contours of this doctrine remain uncertain.

Plaintiff Trustees of Boston University (BU) owned a patent covering LED semiconductor devices. The devices incorporated gallium nitride (GaN), a composition that emits blue light and was notoriously difficult to fabricate as part of an LED. LEDs typically include a substrate and several layers. The solid-state materials comprising the layers may be monocrystalline (arranging all material in a single crystal structure), polycrystalline (combining multiple smaller crystal structures), or amorphous (non-crystalline).

One common method for fabricating semiconductor layers, called epitaxy, involves depositing semiconductor material onto a substrate. The deposited layer attempts to mimic the crystal lattice structure of the substrate as it grows. However, defects can arise if the lattice structures of the deposited layer and the substrate do not match. BU recognized that it was difficult to grow monocrystalline GaN on a substrate using epitaxy given a mismatch in the structure of the GaN and the substrate. BU solved the problem by first depositing a "buffer layer" of an amorphous GaN film on the substrate, then raising the temperature to crystallize the amorphous layer, and finally growing monocrystalline GaN on the crystallized layer.

BU received a patent on a device fabricated using this process. The relevant claim recited a semiconductor device comprising a substrate, "a non-single crystalline buffer layer" of GaN grown on the substrate, and "a growth layer grown on the buffer layer," the growth layer comprising GaN. Accusing various defendants of infringement, BU argued that "non-single crystalline buffer layer" meant the layer was "not monocrystalline." The district court interpreted the claim in line with this proposal, finding that the buffer layer could be polycrystalline, amorphous, or a mixture of polycrystalline and amorphous. The court found that the claimed semiconductor device comprised six permutations: a monocrystalline growth layer formed (1) indirectly (i.e., with an intervening layer) on a polycrystalline layer; (2) indirectly on a layer that is a mixture of polycrystalline and amorphous; (3) indirectly on an amorphous layer; (4) directly on a polycrystalline layer; (5) directly on a layer that is a mixture of polycrystalline and amorphous; or (6) directly on an amorphous layer.

A jury found the patent valid and infringed. In challenging the verdict, the defendants argued that the asserted claim was invalid for lack of enablement, because the patent did not teach one of the six permutations—that is, fabricating an LED with a monocrystalline growth layer formed directly on an amorphous layer. However, the district court denied the renewed JMOL motion and concluded that it was unnecessary for the patent to enable a device embodying this permutation.

The Federal Circuit reversed and stressed that it was indisputably impossible to fabricate this permutation using epitaxy, the only method taught in the patent. As a patent must enable the full scope of the claimed invention, failure to enable one of the permutations covered by the claim rendered the claim invalid. The court noted that "to some extent, BU created its own enablement problem" with its proposed claim construction. Having obtained the construction it sought, which included a physically impossible embodiment, "BU then needed to successfully defend against an enablement challenge as to the claim's full scope." The decision reminds patent owners that they must carefully consider enablement issues when crafting claim constructions to target accused infringers.

One notable aspect of this decision is the potential tension with an earlier line of cases holding that patent claims do not necessarily lack enablement solely because they embrace inoperative embodiments, provided artisans in the field would know how to determine, without undue experimentation, which embodiments would work. See Atlas Powder Co. v. E.I. du Pont De Nemours & Co., 750 F.2d 1569, 1576-77 (Fed. Cir. 1984). Given the parties' agreement that it would be impossible to grow a monocrystalline film directly on an amorphous layer using epitaxy, one perhaps could have reasonably argued that artisans would have known that this embodiment was inoperative and could thus practice the invention without undue experimentation.
Atlas involved a patent claiming an emulsion useful as a blasting agent for mining and construction. The accused infringer argued that the patent was not enabled because it listed numerous salts, fuels, and emulsifiers that could form thousands of emulsions without teaching which combinations would work. The Federal Circuit disagreed and concluded that artisans would have known know how to select a salt and a fuel, determine a proper emulsifier, and ultimately achieve an operable combination.

One could potentially square BU with Atlas by reading an "inoperative embodiment" to be one that can be physically made, but is not useful for its intended purpose, as opposed to a permutation or embodiment that is physically impossible to make. In In re Cook, 439 F.2d 730 (C.C.P.A. 1971), the Federal Circuit's predecessor held that claims covering lenses with specified parameters were not invalid for lack of enablement despite encompassing "inoperative embodiments" of lenses with parameters within the recited ranges, but that were not useful as zoom lenses as intended because "it would be obvious to those skilled in lens design whether a given embodiment within the indicated ranges, once conceived, would or would not be useful as a zoom lens."

Of course, there have been other cases since Atlas invalidating patents for failure to enable the full scope of claims. E.g., Liebel-Flarsheim Co. v. Medrad, 481 F.3d 1371 (Fed. Cir. 2007) (claims covering injectors with and without a pressure jacket not enabled where patent taught only injectors with a pressure jacket). Some, like Liebel-Flarsheim, even involved situations in which the patentee intentionally crafted broad claims that proved to be the patent's downfall. However, these cases generally involved claims covering embodiments that were not necessarily impossible to achieve (even though the specifications failed to enable them). BU seems to break new ground in that five out of six permutations were indisputably possible to make, and the last was indisputably impossible.

One question that arises is whether an otherwise non-enabled claim could be enabled if one of ordinary skill would understand the claim to exclude impossible embodiments. Some cases suggest this is a viable approach to avoid inoperative embodiments. E.g., In re of Geerdes, 491 F.2d 1260, 1265 (C.C.P.A. 1974) ("Having stated the objective (foamed product) together with the process steps, use of materials which might prevent achievement of the objective (by rendering the process inoperative) can hardly be said to be within the scope of the claims."). Generally, validity does not factor into claim construction unless the claim is otherwise ambiguous. See Phillips v. AWH, 415 F.3d 1303, 1327 (Fed. Cir. 2005) (en banc). The question, then, is whether a court would have accepted an argument by BU that one of ordinary skill would understand the claim to exclude the permutation of a monocrystalline layer formed directly on an amorphous layer because it was known to be impossible—not because this construction is necessary to preserve validity, but because it is how one of ordinary skill would understand the claim.

Another question is whether a broad claim embracing a vast number of possible embodiments could be enabled while a narrower claim covering a finite set of permutations could lack enablement. For example, consider a first claim to "a pharmaceutical formulation comprising micronized ibuprofen" and a second claim to "a pharmaceutical formulation comprising micronized ibuprofen with a particle size of 2-10 micrometers." Suppose it is physically impossible to make micronized ibuprofen with particles of less than 5 micrometers. Is the first claim enabled because it does not specify the size of the particles, while the second is not enabled? It seems counterintuitive that a broader claim encompassing a potentially limitless number of embodiments could be enabled while a narrower claim with a finite number of embodiments could lack enablement.

To date, no case has cited BU for its implications as to enablement of claims covering impossible embodiments. These questions remain open for resolution another day.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

To print this article, all you need is to be registered on Mondaq.com.

Click to Login as an existing user or Register so you can print this article.

Similar Articles
Relevancy Powered by MondaqAI
In association with
Related Topics
Similar Articles
Relevancy Powered by MondaqAI
Related Articles
Related Video
Up-coming Events Search
Font Size:
Mondaq on Twitter
Mondaq Free Registration
Gain access to Mondaq global archive of over 375,000 articles covering 200 countries with a personalised News Alert and automatic login on this device.
Mondaq News Alert (some suggested topics and region)
Select Topics
Registration (please scroll down to set your data preferences)

Mondaq Ltd requires you to register and provide information that personally identifies you, including your content preferences, for three primary purposes (full details of Mondaq’s use of your personal data can be found in our Privacy and Cookies Notice):

  • To allow you to personalize the Mondaq websites you are visiting to show content ("Content") relevant to your interests.
  • To enable features such as password reminder, news alerts, email a colleague, and linking from Mondaq (and its affiliate sites) to your website.
  • To produce demographic feedback for our content providers ("Contributors") who contribute Content for free for your use.

Mondaq hopes that our registered users will support us in maintaining our free to view business model by consenting to our use of your personal data as described below.

Mondaq has a "free to view" business model. Our services are paid for by Contributors in exchange for Mondaq providing them with access to information about who accesses their content. Once personal data is transferred to our Contributors they become a data controller of this personal data. They use it to measure the response that their articles are receiving, as a form of market research. They may also use it to provide Mondaq users with information about their products and services.

Details of each Contributor to which your personal data will be transferred is clearly stated within the Content that you access. For full details of how this Contributor will use your personal data, you should review the Contributor’s own Privacy Notice.

Please indicate your preference below:

Yes, I am happy to support Mondaq in maintaining its free to view business model by agreeing to allow Mondaq to share my personal data with Contributors whose Content I access
No, I do not want Mondaq to share my personal data with Contributors

Also please let us know whether you are happy to receive communications promoting products and services offered by Mondaq:

Yes, I am happy to received promotional communications from Mondaq
No, please do not send me promotional communications from Mondaq
Terms & Conditions

Mondaq.com (the Website) is owned and managed by Mondaq Ltd (Mondaq). Mondaq grants you a non-exclusive, revocable licence to access the Website and associated services, such as the Mondaq News Alerts (Services), subject to and in consideration of your compliance with the following terms and conditions of use (Terms). Your use of the Website and/or Services constitutes your agreement to the Terms. Mondaq may terminate your use of the Website and Services if you are in breach of these Terms or if Mondaq decides to terminate the licence granted hereunder for any reason whatsoever.

Use of www.mondaq.com

To Use Mondaq.com you must be: eighteen (18) years old or over; legally capable of entering into binding contracts; and not in any way prohibited by the applicable law to enter into these Terms in the jurisdiction which you are currently located.

You may use the Website as an unregistered user, however, you are required to register as a user if you wish to read the full text of the Content or to receive the Services.

You may not modify, publish, transmit, transfer or sell, reproduce, create derivative works from, distribute, perform, link, display, or in any way exploit any of the Content, in whole or in part, except as expressly permitted in these Terms or with the prior written consent of Mondaq. You may not use electronic or other means to extract details or information from the Content. Nor shall you extract information about users or Contributors in order to offer them any services or products.

In your use of the Website and/or Services you shall: comply with all applicable laws, regulations, directives and legislations which apply to your Use of the Website and/or Services in whatever country you are physically located including without limitation any and all consumer law, export control laws and regulations; provide to us true, correct and accurate information and promptly inform us in the event that any information that you have provided to us changes or becomes inaccurate; notify Mondaq immediately of any circumstances where you have reason to believe that any Intellectual Property Rights or any other rights of any third party may have been infringed; co-operate with reasonable security or other checks or requests for information made by Mondaq from time to time; and at all times be fully liable for the breach of any of these Terms by a third party using your login details to access the Website and/or Services

however, you shall not: do anything likely to impair, interfere with or damage or cause harm or distress to any persons, or the network; do anything that will infringe any Intellectual Property Rights or other rights of Mondaq or any third party; or use the Website, Services and/or Content otherwise than in accordance with these Terms; use any trade marks or service marks of Mondaq or the Contributors, or do anything which may be seen to take unfair advantage of the reputation and goodwill of Mondaq or the Contributors, or the Website, Services and/or Content.

Mondaq reserves the right, in its sole discretion, to take any action that it deems necessary and appropriate in the event it considers that there is a breach or threatened breach of the Terms.

Mondaq’s Rights and Obligations

Unless otherwise expressly set out to the contrary, nothing in these Terms shall serve to transfer from Mondaq to you, any Intellectual Property Rights owned by and/or licensed to Mondaq and all rights, title and interest in and to such Intellectual Property Rights will remain exclusively with Mondaq and/or its licensors.

Mondaq shall use its reasonable endeavours to make the Website and Services available to you at all times, but we cannot guarantee an uninterrupted and fault free service.

Mondaq reserves the right to make changes to the services and/or the Website or part thereof, from time to time, and we may add, remove, modify and/or vary any elements of features and functionalities of the Website or the services.

Mondaq also reserves the right from time to time to monitor your Use of the Website and/or services.


The Content is general information only. It is not intended to constitute legal advice or seek to be the complete and comprehensive statement of the law, nor is it intended to address your specific requirements or provide advice on which reliance should be placed. Mondaq and/or its Contributors and other suppliers make no representations about the suitability of the information contained in the Content for any purpose. All Content provided "as is" without warranty of any kind. Mondaq and/or its Contributors and other suppliers hereby exclude and disclaim all representations, warranties or guarantees with regard to the Content, including all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement. To the maximum extent permitted by law, Mondaq expressly excludes all representations, warranties, obligations, and liabilities arising out of or in connection with all Content. In no event shall Mondaq and/or its respective suppliers be liable for any special, indirect or consequential damages or any damages whatsoever resulting from loss of use, data or profits, whether in an action of contract, negligence or other tortious action, arising out of or in connection with the use of the Content or performance of Mondaq’s Services.


Mondaq may alter or amend these Terms by amending them on the Website. By continuing to Use the Services and/or the Website after such amendment, you will be deemed to have accepted any amendment to these Terms.

These Terms shall be governed by and construed in accordance with the laws of England and Wales and you irrevocably submit to the exclusive jurisdiction of the courts of England and Wales to settle any dispute which may arise out of or in connection with these Terms. If you live outside the United Kingdom, English law shall apply only to the extent that English law shall not deprive you of any legal protection accorded in accordance with the law of the place where you are habitually resident ("Local Law"). In the event English law deprives you of any legal protection which is accorded to you under Local Law, then these terms shall be governed by Local Law and any dispute or claim arising out of or in connection with these Terms shall be subject to the non-exclusive jurisdiction of the courts where you are habitually resident.

You may print and keep a copy of these Terms, which form the entire agreement between you and Mondaq and supersede any other communications or advertising in respect of the Service and/or the Website.

No delay in exercising or non-exercise by you and/or Mondaq of any of its rights under or in connection with these Terms shall operate as a waiver or release of each of your or Mondaq’s right. Rather, any such waiver or release must be specifically granted in writing signed by the party granting it.

If any part of these Terms is held unenforceable, that part shall be enforced to the maximum extent permissible so as to give effect to the intent of the parties, and the Terms shall continue in full force and effect.

Mondaq shall not incur any liability to you on account of any loss or damage resulting from any delay or failure to perform all or any part of these Terms if such delay or failure is caused, in whole or in part, by events, occurrences, or causes beyond the control of Mondaq. Such events, occurrences or causes will include, without limitation, acts of God, strikes, lockouts, server and network failure, riots, acts of war, earthquakes, fire and explosions.

By clicking Register you state you have read and agree to our Terms and Conditions