United States: Opportunity For Equivalents In Claim Amendments

It is commonly held that the doctrine of equivalents is lost when claim amendments are made during patent prosecution. That is, any claim amendment that is made during patent prosecution surrenders or gives up elements which are equivalent to those elements claimed in the amendment.  Surrender of the doctrine of equivalents places the burden on the patent Applicant, and the patent practitioner representing the Applicant, to carefully consider any amendments to the claims prior to issuance of the patent (when such occurs).  This principle is neatly summed up in the rulings on the following two cases.

In re Zletz, 893 F.2d 319, 322, 13 USPQ2d 1320, 1322 (Fed. Cir. 1989) (manner of claim interpretation that is used by courts in litigation is not the manner of claim interpretation that is applicable during prosecution of a pending application before the PTO).  Sage Prods., Inc. v. Devon Indus., Inc., 126 F.3d 1420, 1425, 44 USPQ2d 1103, 1107 (Fed. Cir. 1997) (patentee who had a clear opportunity to negotiate broader claims during prosecution but did not do so, may not seek to expand the claims through the doctrine of equivalents, for it is the patentee, not the public, who must bear the cost of failure to seek protection for this foreseeable alteration of its claimed structure).

What does this mean for the patent practitioner?  The claims as originally filed in a non-provisional patent application have full use of the doctrine of equivalents.  In an infringement proceeding, any claim that is granted as originally filed covers not only the literal elements in the claims but the equivalents of those elements.  But, an amended claim loses the equivalents.  So, the patent practitioner should exercise caution and prudence when amending claims.  Usually, a claim is amended during patent prosecution to clarify the meaning of a claim element, or to narrow or broaden the extent of a claim element in light of art that is cited by the Examiner.  As the Sage ruling above warns us, we have the opportunity to negotiate broader claims during prosecution.  If we don't take advantage of this opportunity to establish a desired breadth of any claim element amended, we give up that broader breadth.

Some examples may illuminate.  In an electronics patent application, suppose the claim as originally filed recites MOS transistors.  But, the specification teaches that bipolar transistors could also be used in a circuit, as could relays, etc.  If the claim as originally filed is granted, it may be possible to argue that the claim covers other types of transistors and also relays and so on, as these are equivalent to the MOS transistors recited in the claim.  If, during prosecution, the claims are amended to recite NMOS transistors (e.g., because some of the art cites a PMOS transistor embodiment and there is good reason to argue that an NMOS embodiment is not shown in the art), then the claims only cover NMOS transistors.  It will not be possible to argue that the claim covers other types of transistors and also relays, because these equivalents have been surrendered in the amendment.

In a mechanical patent application, suppose the claim as originally filed recites threaded fasteners.  But, the specification teaches that nails, welding, rivets, etc. could also be used to hold something together.  If the claim is amended to recite nuts and bolts, instead of threaded fasteners, then screws, which are not nuts and bolts, and nails and rivets, etc. are surrendered through loss of the equivalents.

Now, supposing in each of these cases, there are other arguments to be made that differentiate the claims from the art, and these other arguments don't depend on the narrowing as described above.  If the patent practitioner carelessly leaves the above amendments in place, the equivalents are surrendered needlessly, and the issued patent is narrower than was necessary in light of the cited art.  This situation is to be avoided.  What should a practitioner do?

When other arguments are found successful against cited art, one strategy is to revisit previous amendments and carefully consider whether a broadening amendment could then be made so that the literal equivalents are captured in the claims.  In the electronics example, suppose an amendment is made elsewhere in the claim, and the limitations regarding NMOS transistors are amended to recite transistors, or better still, switches (provided the specification explains that various types of transistors, relays, etc. can be used as switches).  Now, the amended claim element recites switches, and has literal coverage for the types of equivalents the Applicant intends.  In the mechanical example, suppose an amendment is made elsewhere in the claim, and the limitations regarding nuts and bolts are amended to recite fasteners, or attachment, or some other broader term, or a list of devices that fasten or attach two materials together.  Now, the amended claim recites the literal coverage for the types of equivalents the Applicant intends.  This is taking advantage of the opportunity that the above cases suggest is before us.  Failing to take advantage of this opportunity may have dire costs for the Applicant, in terms of lost claims coverage.  Of course, art cited by the Examiner should be considered, as the above tactic of broadening may reintroduce art earlier eliminated by the initial narrowing amendment and arguments.  The broadening tactic is successful only if the claims, as amended as a whole, do not read on any of the art under 35 USC §102 and 35 USC §103.

There are also more subtle aspects to this.  Comparison language such as less than or equal to, greater than or equal to, thresholds and limits may also be subject to the loss of equivalents in amendment.  Words and phrases such as "or", "and", "one of" versus "at least one of" or "one or more of" may be subject to strict scrutiny during Markman hearings, and the doctrine of equivalents may have bearing on the scope of the claims.  Watch these carefully, and amend these prudently.  The doctrine of equivalents, and loss thereof through amendments, is a recommended awareness to have in the art of patenting.

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
Smith Gambrell & Russell LLP
In association with
Related Topics
Similar Articles
Relevancy Powered by MondaqAI
Smith Gambrell & Russell LLP
Related Articles
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
Registration (you must 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