UK: Double Jeopardy And European Patents

Last Updated: 27 March 2003
Article by Neil Thomson

A recent EPO decision has challenged the conventional exclusion on double patenting. Neil Thomson asks where the decision leaves EPO practice, and what impact it will have on proceedings in the UK.

"It is an accepted principle in most patent systems that two patents shall not be granted to the same applicant for one invention" (Guidelines for Examination at the EPO, C-IV, 6.4)".

Or is it? A recent Technical Board of Appeal of the European Patent Office (EPO) has considered whether there is any legal basis for the above practice and, for a specific set of facts, concluded that there is not.

Technical Board of Appeal Decision T587/98

In the case appealed, the applicant Komag Inc filed a European application EP 91115600.8, claim 1 of which related to, inter alia, a structure comprising three layers in addition to a substrate: namely, a first dielectric layer formed on said substrate, a magneto-optic (recording) layer formed on said dielectric layer and a second dielectric layer formed on said magneto-optic layer.

Subsequently, a divisional application EP 95100700.4, was filed, the main claim of which claimed at least two layers in addition to the substrate: namely a recording layer which may be an optical or a magneto-optical layer, and a dielectric layer which may be formed either on the recording layer or between it and the substrate.

Denoting the combination of substrate, first dielectric layer and recording layer as 'A' and the second dielectric layer as 'B', the parent effectively claimed 'A' with 'B', while the divisional claimed just 'A'(implicitly with or without 'B').

At first instance the Examining Division of the EPO refused the divisional application since, in their view, the claims conflicted with those of the parent application. The decision was based on the Guidelines for Examination which state:

C-IV, 6.4 "The Convention does not deal explicitly with the case of co-pending European applications of the same effective date. However, it is an accepted principle in most patent systems that two patents shall not be granted to the same applicant for one invention. It is permissible to allow an applicant to proceed with two applications having the same description where the claims are distinct in scope and directed to different inventions. However, in the rare case in which there are two or more European applications from the same applicant ... and the claims of those applications have the same priority date and relate to the same invention ... the applicant should be told that he must either amend one or more of the applications in a manner that they no longer claim the same invention, or choose which one of those applications he wishes to proceed to grant."

C-VI,9.6 "The parent and divisional applications may not claim the same subject-matter (See IV, 6.4). This means not only that they must not contain claims of substantially identical scope, but also that one application must not claim the subject-mater claimed in the other, even in different words. The difference between the claimed subject-matter of the two applications must be clearly distinguishable. As a general rule, however, one application may claim its own subject-matter in combination with that of the other application. In other words, if the parent and divisional applications claim separate and distinct elements 'A' and 'B' respectively which function in combination, one of the two applications may also include a claim for 'A' plus 'B' ".

The applicant appealed the refusal. The applicant argued that a ban on "double patenting" had no basis in the European Patent Convention and that in any case the claims of the parent and divisional were not for "the same invention".

In T587/98 a Board of Appeal observed that Article 125 of the EPC allows the EPO to take account of the principles of procedural law generally recognized in the contracting states where there is an absence of procedural provisions in the European Patent Convention. However, the Board concluded (reversing the previous decision) that the "institution of a divisional patent" was a matter for substantive law rather than a matter of procedure. Thus, the Board concluded that the practice laid down by the EPC relating to divisional applications is "self-contained and complete".

In view of the above, the Board went on to conclude that in the specific case of parent and divisional applications there is no express or implicit provision in the EPC which prohibits the presence in a divisional application of "an independent claim which is related to an independent claim in the parent application in such a way that the 'parent' claim includes all the features of the 'divisional' claim combined with an additional feature". However, the Board was careful not to reach any conclusions with wider applicability to the case of "double-patenting". What are the implications of this decision? As acknowledged by the Board itself, it is possible that there will be a proliferation of divisional applications all with overlapping scopes. As a result, third parties may face 'double jeopardy' - simultaneously infringing multiple patents - all of which have originated from a single filing.

Impact of Decision T587/98 in the UK

What impact will the Decision have in the UK? Article 139(3) EPC states:

"Any contracting state may prescribe whether and on what terms an invention disclosed in both a European patent application or patent and a national application or patent having the same date of filing, or where priority is claimed, the same date of priority, may be protected simultaneously by both applications or patents".

The UK Patents Act 1977 has exercised this power through the wording of Section 73(2), as amended, to deal with conflicting European (UK) and national UK patents:

"If it appears to the Comptroller that a patent under this Act and a European patent (UK) have been granted for the same invention having the same priority date and that the applications for the patents were filed by the same applicant or his successor in title...the Comptroller shall revoke the patent [under this Act]".

The clear intention of Section 73(2) was explained by the Court of Appeal in Marley's Patent ([1994]) RPC 231) where it was held that the correct construction of subsection (2) is the literal one. Balcombe LJ held:

It seems to me that the obvious purpose of [Section 73(2)] is to enable the Comptroller to prevent there being in existence two patents for the same invention, having the same priority date and where the applications for both patents were filed by the same applicant, and this is irrespective of the fact that other linked inventions may be included in the claims of either patent. The existence in these circumstances of concurrent patents for the same invention would not only be administratively undesirable, but could result in a defendant who has successfully defeated a claim for infringement of one patent being threatened with proceedings for infringement of the other in relation to the same activities. If the construction adopted by the judge - that the purpose of Section 73(2) is to prevent the similarity, but not the overlapping, of monopolies - were correct it would always be possible to circumvent operation of the sub-section by including in the claims of one patent two linked inventions (I1 and I2), but to include in the claim of the other patent only one of the inventions (I1).

Further, Section 18(5) of the Patents Act 1977 prevents two national UK patents being granted for the same invention having the same priority date and applicant.

It is clear that the EPO Board's definition of "the same invention" and "conflicting claims" as contained in the Guidelines for Examination is significantly different to the UK Courts' interpretation of the same terms as applied to the Patents Act 1977.

The UK Patents Act contains clear rules regarding conflict between two national UK applications and between UK national and European (UK) patents. But what happens in the case where both patents are European (UK) patents? Section 18(5) is limited to applications under the 1977 Act, and in any case refers only to pre-grant applications. Section 73(2) refers only to conflict between European (UK) and national UK patents. In addition, the Comptroller's powers are limited to revocation of the national patent; no action can be taken against a European (UK) patent. As such, it would appear that the Comptroller has no power to revoke one of two European (UK) patents resulting from two European patents granted further to two applications prosecuted through the European Patent Office.


The Decision T587/98 has called into question whether the double patenting exclusion of most patent systems is an exclusion that can be found in the European Patent Convention. For a particular set of facts one EPO Board of Appeal ruled that two patents with overlapping claims could be granted in a parent application and an application divided therefrom.

The United Kingdom patent law appears to have no provisions preventing the enforcement of two European (UK) patents with overlapping claims resulting from a single parent application. Thus the situation considered undesirable by Balcombe, LJ in Marley's Patent could apply in the United Kingdom after all and a defendant may face the double jeopardy of infringing two patents granted with overlapping claims for a single invention.

© 2001. Boult Wade Tennant

This article was first published in the April 2001 issue of Managing Intellectual Property.

The content of this article does not constitute legal advice and should not be relied on in that way. Specific advice should be sought about your specific circumstances.

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

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 (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

To Use 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