United States: Delaware Judges Are Finding Patent Claims Indefinite Post-Nautilus

It has been a little more than a year since the Supreme Court rendered its decision in Nautilus, lowering the standard for finding patent claim terms indefinite. Many commentators at that time predicted the decision would have broad implications for all patent cases where definiteness is at issue. Two recent cases from the District of Delaware demonstrate the accuracy of those predictions as judges in Delaware have seized upon the holding in Nautilus to find patent claim terms indefinite. Practitioners asserting or defending against patent claims would do well to acquaint themselves with the strategies and pitfalls raised by the recent decisions to ensure they provide the best advocacy.

The definiteness requirement for patent claim terms is rooted in 35 U.S.C. § 112, ¶ 2, which provides that "the specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention." The old Federal Circuit standard prior to Nautilus upheld claims as definite so long as they were "amendable to construction" and not "insolubly ambiguous." The Supreme Court altered that standard in Nautilus and now requires "that a patent's claims, viewed in light of the specification and prosecution history, inform those skilled in the art about the scope of the invention with reasonable certainty." Nautilus, Inc. v. Biosig Instruments, Inc., 134 S.Ct. 2120, 2129 (2014).  The Federal Circuit has scoffed at the modified standard provided by the Supreme Court, noting that lower courts "may now steer by the bright star of 'reasonable certainty,' rather than the unreliable compass of 'insoluble ambiguity.'"  Biosig Instruments, Inc. v. Nautilus, Inc., 783 F.3d 1374, 1379 (Fed. Cir. 2015).

Nonetheless, the holding in Nautilus was recently cited by Judge Sue Robinson in the District of Delaware in finding the claims of 6 patents invalid. Cox Communs. Inc. v. Sprint Communs. Co., No. 12-487-SLR, 2015 U.S. Dist. LEXIS 64252 (D. Del. May 15, 2015). In Cox, the parties disputed whether the claim limitation "processing system" is indefinite. Cox argued that the limitation is indefinite because the structural limitation, "processing system," is only described functionally in the patents. Sprint's expert opined that the patents reference other patents which use the phrase "processing system," demonstrating that a person of ordinary skill in the art would have known with reasonable certainty what is meant by the limitation. Another expert, however, countered that assertion by selecting five patents of the twenty five identified by Sprint's expert as using "processing system" in their claims, and explaining that the phrase is used differently in each of the five patents sampled, with different structures and specialized software to perform widely differing functions.

The court in Cox concluded that the physical structures were only functionally described by the claims and by the patent specifications and, thus, did not pass muster under Nautilus as a person of ordinary skill in the art is not provided with the bounds of the claimed invention. The court agreed that the limitation "processing system" is used differently in a sampling of other patents, and found it significant that the parties did not provide, nor was the court able to find, a dictionary definition for the phrase "processing system." The court rejected Sprint's proposed construction because it felt that it only described the "processing system" by its function rather than structure, and the court concluded that there is no established meaning in the art for the disputed limitation.

Another recent decision in the District of Delaware by Judge Gregory Sleet applied the holding in Nautilus to find a patent claim term indefinite. Bayer Intellectual Prop. GmbH v. Warner Chilcott Co., No. 12-1032-GMS, 2015 U.S. Dist. LEXIS 52061 (D. Del. Apr. 21, 2015).  In Bayer, the court previously issued a claim construction order finding that words of degree in a claim term including "high," "low," "satisfactory," and "reliable" had no standards against which to draw comparisons, and that the patent offered no suggestions for how to measure those criteria. Bayer had not sought reconsideration of the claim construction ruling, but nonetheless contended in opposing a summary judgment motion that the disputed term is not indefinite because one skilled in the art would understand with reasonable certainty its meaning, as demonstrated by extrinsic evidence. Bayer provided dozens of pieces of extrinsic evidence, as well as a supplemental declaration from its expert, in support of a new argument that the disputed term and the words of degree simply indicate that the claimed invention performs comparably to other products on the market.

The court found that Bayer's efforts to reargue claim construction with entirely new evidence was improper and, thus, maintained the finding of indefiniteness. The decision went on to indicate that the court would reach the same result of indefiniteness for several reasons even if it were to accept the additional extrinsic evidence and allow Bayer to assert a new construction. First, the court explained that the proposed construction and the underlying extrinsic evidence conflicts with the intrinsic record of the patent, which violates a basic tenet of claim construction. Second, the court reasoned that conflicting interpretations of the disputed term offered by Bayer's expert in his two declarations underscored the fact that the patent fails to inform, with reasonable certainty, those skilled in the art about the scope of the invention. Third, the court found that Bayer's proposed construction using the word "comparable" was itself subjective and without defined boundaries. The court thus found on summary judgment that the patent claim is indefinite and invalid.

In light of the above recent cases, it is now more important than ever for practitioners to marshal all available evidence regarding the meaning of disputed claim terms well in advance of the claim construction hearing. The gathering of evidence should include extrinsic evidence and any available dictionary definitions to show a commonly understood meaning by the plaintiff, or a showing of the lack of such evidence to demonstrate a lack of a commonly understood meaning by the defendant. The cases also show a need to have expert reports with well thought out positions ready for the claim construction hearing to compare the extrinsic evidence with the intrinsic record and support the claim construction arguments. The cases further highlight the need for proposed claim constructions to be structural for structural claim terms and to also be definite. Finally, the cases provide a reason for defendants to take a shot at indefiniteness for patent claim terms with the expectation that their arguments will be seriously considered in light of the Nautilus standard.

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.

In association with
Related Video
Up-coming Events Search
Font Size:
Mondaq on Twitter
Register for Access and our Free Biweekly Alert for
This service is completely free. Access 250,000 archived articles from 100+ countries and get a personalised email twice a week covering developments (and yes, our lawyers like to think you’ve read our Disclaimer).
Email Address
Company Name
Confirm Password
Mondaq Topics -- Select your Interests
 Law Performance
 Law Practice
 Media & IT
 Real Estate
 Wealth Mgt
Asia Pacific
European Union
Latin America
Middle East
United States
Worldwide Updates
Check to state you have read and
agree to our Terms and Conditions

Terms & Conditions and Privacy Statement

Mondaq.com (the Website) is owned and managed by Mondaq Ltd and as a user you are granted a non-exclusive, revocable license to access the Website under its terms and conditions of use. Your use of the Website constitutes your agreement to the following terms and conditions of use. Mondaq Ltd may terminate your use of the Website if you are in breach of these terms and conditions or if Mondaq Ltd decides to terminate your license of use for whatever reason.

Use of www.mondaq.com

You may use the Website but are required to register as a user if you wish to read the full text of the content and articles available (the Content). 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 & conditions or with the prior written consent of Mondaq Ltd. You may not use electronic or other means to extract details or information about Mondaq.com’s content, users or contributors in order to offer them any services or products which compete directly or indirectly with Mondaq Ltd’s services and products.


Mondaq Ltd and/or its respective suppliers make no representations about the suitability of the information contained in the documents and related graphics published on this server for any purpose. All such documents and related graphics are provided "as is" without warranty of any kind. Mondaq Ltd and/or its respective suppliers hereby disclaim all warranties and conditions with regard to this information, including all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement. In no event shall Mondaq Ltd 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 or performance of information available from this server.

The documents and related graphics published on this server could include technical inaccuracies or typographical errors. Changes are periodically added to the information herein. Mondaq Ltd and/or its respective suppliers may make improvements and/or changes in the product(s) and/or the program(s) described herein at any time.


Mondaq Ltd requires you to register and provide information that personally identifies you, including what sort of information you are interested in, for three primary purposes:

  • To allow you to personalize the Mondaq websites you are visiting.
  • To enable features such as password reminder, newsletter alerts, email a colleague, and linking from Mondaq (and its affiliate sites) to your website.
  • To produce demographic feedback for our information providers who provide information free for your use.

Mondaq (and its affiliate sites) do not sell or provide your details to third parties other than information providers. The reason we provide our information providers with this information is so that they can measure the response their articles are receiving and provide you with information about their products and services.

If you do not want us to provide your name and email address you may opt out by clicking here .

If you do not wish to receive any future announcements of products and services offered by Mondaq by clicking here .

Information Collection and Use

We require site users to register with Mondaq (and its affiliate sites) to view the free information on the site. We also collect information from our users at several different points on the websites: this is so that we can customise the sites according to individual usage, provide 'session-aware' functionality, and ensure that content is acquired and developed appropriately. This gives us an overall picture of our user profiles, which in turn shows to our Editorial Contributors the type of person they are reaching by posting articles on Mondaq (and its affiliate sites) – meaning more free content for registered users.

We are only able to provide the material on the Mondaq (and its affiliate sites) site free to site visitors because we can pass on information about the pages that users are viewing and the personal information users provide to us (e.g. email addresses) to reputable contributing firms such as law firms who author those pages. We do not sell or rent information to anyone else other than the authors of those pages, who may change from time to time. Should you wish us not to disclose your details to any of these parties, please tick the box above or tick the box marked "Opt out of Registration Information Disclosure" on the Your Profile page. We and our author organisations may only contact you via email or other means if you allow us to do so. Users can opt out of contact when they register on the site, or send an email to unsubscribe@mondaq.com with “no disclosure” in the subject heading

Mondaq News Alerts

In order to receive Mondaq News Alerts, users have to complete a separate registration form. This is a personalised service where users choose regions and topics of interest and we send it only to those users who have requested it. Users can stop receiving these Alerts by going to the Mondaq News Alerts page and deselecting all interest areas. In the same way users can amend their personal preferences to add or remove subject areas.


A cookie is a small text file written to a user’s hard drive that contains an identifying user number. The cookies do not contain any personal information about users. We use the cookie so users do not have to log in every time they use the service and the cookie will automatically expire if you do not visit the Mondaq website (or its affiliate sites) for 12 months. We also use the cookie to personalise a user's experience of the site (for example to show information specific to a user's region). As the Mondaq sites are fully personalised and cookies are essential to its core technology the site will function unpredictably with browsers that do not support cookies - or where cookies are disabled (in these circumstances we advise you to attempt to locate the information you require elsewhere on the web). However if you are concerned about the presence of a Mondaq cookie on your machine you can also choose to expire the cookie immediately (remove it) by selecting the 'Log Off' menu option as the last thing you do when you use the site.

Some of our business partners may use cookies on our site (for example, advertisers). However, we have no access to or control over these cookies and we are not aware of any at present that do so.

Log Files

We use IP addresses to analyse trends, administer the site, track movement, and gather broad demographic information for aggregate use. IP addresses are not linked to personally identifiable information.


This web site contains links to other sites. Please be aware that Mondaq (or its affiliate sites) are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of these third party sites. This privacy statement applies solely to information collected by this Web site.

Surveys & Contests

From time-to-time our site requests information from users via surveys or contests. Participation in these surveys or contests is completely voluntary and the user therefore has a choice whether or not to disclose any information requested. Information requested may include contact information (such as name and delivery address), and demographic information (such as postcode, age level). Contact information will be used to notify the winners and award prizes. Survey information will be used for purposes of monitoring or improving the functionality of the site.


If a user elects to use our referral service for informing a friend about our site, we ask them for the friend’s name and email address. Mondaq stores this information and may contact the friend to invite them to register with Mondaq, but they will not be contacted more than once. The friend may contact Mondaq to request the removal of this information from our database.


This website takes every reasonable precaution to protect our users’ information. When users submit sensitive information via the website, your information is protected using firewalls and other security technology. If you have any questions about the security at our website, you can send an email to webmaster@mondaq.com.

Correcting/Updating Personal Information

If a user’s personally identifiable information changes (such as postcode), or if a user no longer desires our service, we will endeavour to provide a way to correct, update or remove that user’s personal data provided to us. This can usually be done at the “Your Profile” page or by sending an email to EditorialAdvisor@mondaq.com.

Notification of Changes

If we decide to change our Terms & Conditions or Privacy Policy, we will post those changes on our site so our users are always aware of what information we collect, how we use it, and under what circumstances, if any, we disclose it. If at any point we decide to use personally identifiable information in a manner different from that stated at the time it was collected, we will notify users by way of an email. Users will have a choice as to whether or not we use their information in this different manner. We will use information in accordance with the privacy policy under which the information was collected.

How to contact Mondaq

You can contact us with comments or queries at enquiries@mondaq.com.

If for some reason you believe Mondaq Ltd. has not adhered to these principles, please notify us by e-mail at problems@mondaq.com and we will use commercially reasonable efforts to determine and correct the problem promptly.