United States: Why Patent Interference Proceedings Are Worth It

Originally published in The New Jersey Law Journal, July 19, 2004

Copyright © Finnegan, Henderson, Farabow, Garrett & Dunner, LLP

U.S. patent law is unique in recognizing the inventive activity of individuals as significant in deciding who is entitled to patent rights on an invention. Other countries simply rely on the filing date of a patent application to decide who gets a patent. Who actually invented first is not relevant in those countries. In the United States, however, the question of who made an invention first is important in two different situations. One is where the U.S. Patent and Trademark Office (PTO), or a court, decides which of two parties is entitled to a patent on a single invention. This is called a patent interference. The other is where a court decides whether a patent is invalid because someone else made the invention first. This latter situation typically arises as part of an invalidity defense to patent infringement. Both situations are governed by 35 U.S.C. §102(g), and both involve a determination of who is "first to invent." This article explores how a "first to invent" position can be more advantageously pursued in a patent interference rather than a district court action.

While the rules for conception, reduction to practice, and diligence are generally the same in a patent interference proceeding and in an invalidity defense in district court, there are procedural and substantive reasons why a patent interference can be the better forum to vindicate a "first to invent" argument. It may not always be apparent that one has a choice between an interference and an invalidity defense. But here’s how the situation might present itself. Your company might have a breakthrough product that has been carefully protected through filing one or more patent applications. You might even have a portfolio of patents and patent applications covering the product and related technology. You then learn of a new patent owned by the Acme Company broadly claiming an invention that might encompass your company’s breakthrough product.

At this juncture, you typically might obtain an opinion of counsel that Acme’s competing patent is invalid, or that your product does not infringe Acme’s claims, or both. If your initial reaction to Acme’s patent was correct, that is, if Acme’s patent claims do encompass your product, and your product is already protected by issued patent claims, or even pending patent applications, you and your counsel might come to the conclusion Acme’s patent is invalid because your inventor invented the technology first.

It is at this point that routine procedure might dictate that your outside counsel prepare a written opinion asserting the invalidity of Acme’s patent based on your inventor’s earlier work in the field, thus shielding your company from an assertion of willful infringement and the treble damages that go with it. That opinion might also serve [as] the basis of a complaint for declaratory judgment of invalidity. But that opinion will not protect your company from a patent infringement suit, nor will it help solve the problem of Acme’s new patent in the marketplace, which itself might impact your company’s ongoing business apart from any direct attack from Acme. Another option in this circumstance is to provoke an interference with the competing patent. One requirement for admission to an interference is a pending application, preferably filed before the opponent’s application. Thus, if your company has a pending application or is entitled to file a reissue application based on one of its patents, you might take steps to "provoke" an interference with the competing patent. This is usually done by copying or substantially copying the claims of the competing patent within one year of the patent’s issue date, and then filing a Request for Interference. See 35 U.S.C. §135(b); 37 C.F.R. §§ 1.607, 1.608.

The steps involved in provoking the interference vary depending on the respective filing dates of the competing patent application and patent, and may involve some significant strategy decisions regarding the scope and type of claims one wants to pursue. Consideration must be given to the statutory and regulatory framework that has been set up to avoid declaring an interference between what the PTO calls "patentably distinct" claims. See 37 C.F.R. §1.601(n); Eli Lilly & Co. v. Board of Regents of the Univ. of Washington, 334 F.3d 1264 (Fed. Cir. 2003). Additionally, an interference "count," which is similar to a claim and defines the interfering subject matter, should be carefully crafted and suggested to the PTO. The PTO examiner must be satisfied that the claims are allowable and that the application should be sent to the PTO’s Board of Patent Appeals and Interferences (Board), which has the authority to declare the interference and, thereafter, has jurisdiction over the proceeding. If these hurdles are overcome and the Board declares the interference, there are many reasons an interference is preferable to a district court invalidity defense for resolving a priority dispute. Here, in no particular order, are at least ten:

1. The burden of proving priority in an interference is lower than the burden of proving invalidity in a patent infringement action.

Any party in a district court proceeding asserting invalidity, either as a defendant in an infringement action, or as a plaintiff in a declaratory judgment action, bears the burden of proving that invalidity by clear and convincing evidence. On the other hand, in a PTO interference proceeding, where there is no "presumption of validity" as there is in a district court action, the burden is assigned differently, and the standard used is almost always only a preponderance of the evidence.1

Thus, from the hypothetical in the above introduction, if your company asserted invalidity in a district court action, it would necessarily bear the burden of proving that invalidity by clear and convincing evidence. In an interference proceeding, on the other hand, the burden would play out in one of two different ways: if your company’s inventors were the "senior party," that is, if it went into the interference with the earlier effective filing date, the burden of proving priority would be placed from the beginning on Acme; if you were the "junior party," you would bear the burden of proving priority, but only by a preponderance of evidence. Thus, your company in this hypothetical is almost always better off from the burden of proof perspective in an interference proceeding than it is in a district court action.

2. Patentability issues can be raised in addition to priority in an interference.

An interference proceeding is bifurcated into "preliminary motions" and "priority" phases, with separate hearings and decisions for each phase. While an interference is usually considered a priority contest and a prima facie priority case must be evident to get into an interference, there is an opportunity to attack the other party’s claims on grounds other than priority during the preliminary motions period. For example, a party’s claims can be attacked in an interference as unpatentable over the prior art, i.e., the earlier patents and literature. Or a party’s claims can be challenged as failing to meet the enablement or written description requirements. Because a decision on any of the preliminary motions can determine the outcome of the interference before priority is even an issue, e.g. by determining that a patent is invalid, an interference is an attractive option when an interfering party has a strong validity attack on an issued patent.

3. The Board is more likely to understand the issues than a judge or jury.

Another reason an interference before the PTO is a more attractive option than an invalidity defense in district court is the decision-maker’s expertise. The Board has experience in patentability and priority determinations and makes these decisions regularly, as opposed to a judge or jury. Members of the Board all have scientific and technical training, as well as law degrees and significant patent legal training. Many are former PTO examiners. And since the fall of 1998, newly declared interferences have been assigned to what is called the Trial Section of the Board, which is specifically tasked with expediting interferences, particularly the preliminary motions, before the Board. Moreover, a three-member panel makes all significant Board determinations, thus hopefully ensuring three expert decision-makers for each substantive issue that arises in the case.

4. An interference affords flexibility not provided in the district courts.

A patent applicant involved in an interference has the option of amending its claims if they are challenged as unpatentable during an interference. See 37 C.F.R. §1.633(c). Likewise, a patentee hit with a charge of unpatentable claims may have the option of filing a reissue application to amend its claims, which can then be brought into the interference as well. See 37 C.F.R. §1.633(h). There is no similar procedure afforded to parties engaged in litigation before a federal district court.

Importantly, this advantage of interference practice allows a party seeking to provoke an interference who has a pending application to tailor that application to fit the other party’s product or patent claims. For example, a patent applicant facing an infringement charge from a patentee might be concerned about his chances of proving invalidity as a defense in a district court. Even if his current pending claims are not overlapping in scope, he can amend his claims or file a related application to recite the claims he wants provided he has written description support. Likewise, a patentee might use a pending related application to recite claims that explicitly cover an accused product.

5. There is limited discovery in an interference.

From the perspective of many companies (and their attorneys) engaged in patent infringement litigation, discovery is often considered the most onerous, expensive, and time-consuming aspect of the litigation. But discovery is a matter of right afforded to such litigants under the Federal Rules. On the other hand, an interference does not afford the parties discovery as a matter of right. Instead, an interfering party generally has to show the requested discovery is in the interest of justice, which is a higher standard than the relevance standard under the Federal Rules. See 37 C.F.R. §1.687. Discovery is generally frowned upon by the Board, and occurs in only a minority of interferences. While some may consider the limited discovery a disadvantage to provoking an interference, particularly where a party seeks to delay a certain outcome, e.g., pending FDA approval of a product, or where a party’s case hinges on information in the opponent’s possession, there can be no question that this fact serves to streamline the proceedings, usually making an interference a speedier and less expensive proposition than district court litigation.

6. There is no live testimony or trial in an interference.

Another factor impacting the speed and cost of an interference relative to a district court litigation is that testimony in an interference takes the form of affidavits and cross-examination deposition transcripts, and only rarely is testimony given in the presence of a Board member. This is true during both the preliminary motions and priority phases. While there are of course pros and cons to providing live testimony depending on the type of witness giving the testimony, there is more control over the affidavit testimony presented in an interference. Finally, while an oral hearing before a three-judge panel of the Board may and usually does occur at the end of each phase of an interference, these hearings are usually limited to twenty minutes per side.

7. An interference is usually less expensive.

As mentioned above, because of the very limited discovery and lack of live witnesses or trial, interferences are frequently a bargain when compared to full-blown patent infringement litigation. Expert witnesses can play a role in an interference but only on technical, not legal, issues. Thus, interferences do not seem to devolve into the battle of experts that seems so common in patent infringement litigation--saving expenses in this area as well.

Because of the differences among technologies and the varying complexities of interferences, it is nearly impossible to estimate costs for a typical interference. However, because of the bifurcated nature of an interference, it is usually possible to provide ballpark figures for each of the two phases of the interference taking into consideration what is known about the case in the beginning. When comparing these costs to a parallel district court action, the interference usually winds up being much less expensive. That reason alone is enough for many companies to at least consider provoking an interference before embarking on a litigation strategy.

8. There remain opportunities for trial litigation after an interference.

Often, an interference is only the first step in a party’s overall litigation strategy. There is nothing to prevent a party from pursuing a lawsuit in federal court, particularly if discovery or live testimony may be important to the case. Or a party who has been sued for patent infringement may opt to provoke an interference, and then seek a stay in the litigation pending the interference outcome. While courts are often reluctant to grant such stays, they may be more amenable where the issues are highly technical, either from a scientific point of view or a patent law perspective.

Moreover, a final interference decision by the Board can be appealed to a federal district court pursuant to 35 U.S.C. §146. While the Court of Appeals for the Federal Circuit hears most interference appeals, a §146 action is an alternative, and is considered a hybrid of an appeal and a trial de novo. While the record before the PTO is admitted into evidence in a §146 case, the statute explicitly affords the parties the right to take further testimony within certain limits. Unsuccessful patent interferants often choose a §146 action as a means of obtaining evidence that was unavailable at the Board or as a means to present live witnesses. Or some do it simply to drag out the appeal process and delay the issuance of an opponent’s patent.

9. Provoking an interference may afford a party a stronger settlement position.

As mentioned above, a party who is successful in getting an interference declared and set up so that he is senior party has an advantage in the interference: he does not bear the burden of proving priority. Thus, a junior party patentee may be more willing to engage in meaningful settlement discussions with a potential infringer who has provoked an interference with his patent. The Board even requires the parties to engage in settlement discussions at various points during an interference after it has been declared. Thus, a small company who strategically provokes an interference may be able to obtain a better settlement with a patentee than he might otherwise obtain.

10. A successful interference outcome can result in a patent term extension.

While the intricacies of the PTO’s rules for patent term adjustment are beyond the scope of this article, there are provisions for an extension of patent term for delays in the PTO’s examination of an application due to interference proceedings. See 37 C.F.R. §§ 1.701(a)(1), 1.702(c), 1.703(a)(5), 1.703(c). Thus, some of the delays in the PTO’s issuance of a patent caused by engaging in an interference can at least theoretically be recouped at the end of the patent term.


1 See 37 C.F.R. §1.657(b) setting forth the preponderance of the evidence standard where an application has an effective filing date before the opposing patent’s issue date. While §1.657(c) does set forth a clear and convincing standard in an interference where an application has an effective filing date after the competing patent’s issue date, this circumstance is rare and the vast majority of interferences involve the situation outlined in §1.657(b).

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 Topics
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