Article by Stephanie Michiels

This article appeared in the August 2002 issue of Bio-Science Law Review.

Review Of The Changes In Patent Filing Strategies For The Pharmaceuticals And Biotech Industry In Europe In Light Of The Recent Opinion G2/98 1 From The European Patent Office In Respect Of The Requirement For Claiming Priority For The Same Invention.

Introduction

In any patent filing strategy, the benefits associated with filing as quickly as possible to secure the earliest possible date must be carefully balanced with the requirement to generate sufficient technical information to support the patent application. The right of priority has the effect that the date of an earlier application (generally a national application) counts as the date of filing of later applications (usually an International application) filed within a year from the date of filing of the first application. Although disclosures of the invention during the priority year actually occur before the filing date of the later application, they can be overcome by relying on the priority date. In highly competitive and evolutionary areas in particular, it is thus critical to secure a valid priority date for the invention eventually claimed and upon which it can be relied. The validity of the priority right depends on both formal and substantive requirements, including the requirement for claiming in the later application the ‘same invention’ as that disclosed in the earlier application. The question as to what extent a later filed European patent application can claim priority from an earlier application has recently been reconsidered by the European Patent Office1 with a definitive ruling from the Enlarged Board of Appeal.

This article examines the implications that this decision will have for those filing patent applications in the Pharmaceutical and Biotechnology Industries.

Background: The Priority System

Typically, any patent application that is filed today in the pharmaceutical and biotechnology sectors claims at least one earlier priority date from a domestically filed national patent application. The facility to do this, of course, arises from the Paris Convention2 which permits an inventor (or successor in title) to enjoy a priority period of 12 months from the date of first filing within which corresponding applications can be filed in any other member state which is party to the convention. The later filed applications can then rely upon the earlier filed application to overcome any disclosure of the invention during the priority year, thus permitting the inventor to publish the invention in the scientific literature, without invalidating the later filed applications that relate to the same invention. In Europe, provisions similar to those of the Paris Convention have been incorporated into the European Patent Convention3 (EPC) to allow for a claim to priority to be made from an earlier national filing. In particular, Article 87 EPC provides that the later filed European application must be filed during the period of 12 months from the date of filing of the earlier application, and in respect of the same invention as the one disclosed in the earlier application.

While an applicant can freely indicate a priority claim when filing the subsequent European application, generally the question of the validity of the priority claim will only be addressed during substantive examination of the application and only then if prior art is brought to light which may prejudice the patentability of the claims, should the claim to priority be declared invalid. A valid priority right is required when it is necessary to overcome such a prejudicial disclosure which may have been published during the priority year or to overcome the novelty destroying disclosure of a conflicting European application under Article 54(3) EPC4.

In the above circumstances, therefore, establishing whether a priority application is filed in respect of the same invention will determine whether the claim to priority is valid or not. This can be rather uncertain in particular cases where the scope of the claims has been amended during the priority year as is often the case in evolutionary technologies. The question as to whether the same invention is described in an earlier priority document was examined in a number of cases by the EPO but two divergent lines developed.

The EPO case law in respect of the "same invention"

According to EPO practice, the right to claim the priority of a previous first application is determined by and limited to the extent to which the subject matter claimed in the later application has been at least implicitly disclosed in the first application. In an early decision, T81/87 (Preprorennin/COLLABORATIVE)5, which established a stricter narrower approach to priority determination, it was emphasised that when it comes to priority, the disclosure of all the essential elements must be expressed or ‘be directly and unambiguously implied by the text as filed’.

Thus according to this strict approach, the validity of the claim to priority depends on the explicit and implicit disclosure of that subject matter in the earlier application ("Novelty Approach"). Priority will only therefore be accorded to subject-matter disclosed in the application which is directly and unambiguously derivable from the priority document, either explicitly or implicitly.

The second line of case law developed from T73/88 (Snackfood/HOWARD)(6), known as the Snackfood decision. In this Decision, the Technical Board of Appeal adopted a much broader approach and held that priority could be acknowledged for a feature not necessarily disclosed in the priority application as long as that feature is not related to the function and effect of the invention ("Essentiality Approach"). Thus, according to this test, priority for a new feature can be claimed if it is not essential to the way the invention works. At issue in this case was the entitlement to priority of a claim to a snackfood product, including in the pre-characterising portion the feature that the snack food contained "at least 5% by weight of oil and fat" and which was not mentioned in the priority document.

Although the Board considered that the feature added to the claim was "clearly an essential technical feature of the claims in that it has the effect of limiting the extent of the protection conferred by the patent", the Board also emphasised that the feature "is not necessarily an essential feature for the purpose of determining priority (point 2.3 of the Reasons for the Decision). In the Board’s view, "it is clear from the European patent that the additional technical feature ... has nothing to do with the essential character and nature of the invention as such ... The presence of the additional feature does not therefore change the character and nature of the claimed invention as such, in comparison with what is disclosed in the priority document" (point 2.4 of the Reasons for the Decision).

The requirements for claiming priority as applied in T73/88 are at variance with the requirements set out in the Guidelines (C-V, 2.2-2.4) which specify that the basic test for entitlement to priority is equivalent to the test for added matter under Article 123(2) EPC. There is no right to priority if the overall change in the application in view of the previous application results in the skilled person being presented with information which is not directly and unambiguously derivable from the previous application, even when account is taken of matter which is implicit to a person skilled in the art.

The recent ruling of The Enlarged Board of Appeal in G2/98

Recognising this apparent conflict in the evolution of European law, the President of the EPO took the opportunity to refer to the Enlarged Board of Appeal, the following questions:

1a) Does the requirement of the ‘same invention’ in Article 87(1) EPC mean that the extent of the right to priority derivable from a priority application for a later application is determined by, and at the same time limited to, what is at least implicitly disclosed in the priority application?

1b) Or can a lesser degree of correspondence between the priority application and the subject matter claimed in the later application be sufficient in this respect and still justify a right to priority?

After nearly three years of deliberation, the Enlarged Board of Appeal eventually gave its opinion in G2/98 (Requirement of claiming priority in respect of the "same invention"). The Enlarged Board of Appeal(1) in overruling the Snackfood decision confirmed its stricter approach and held that priority for a given feature can only be claimed if that specific feature is directly and unambiguously disclosed in the prior application. Specifically, it was concluded that:

‘the requirement for claiming priority of "the same invention" referred to in Article 87 EPC, means that priority of a previous application in respect of a claim in a European patent application in accordance with Article 88 EPC is to be acknowledged only if the skilled person can derive the subject-matter of the claim directly and unambiguously, using common general knowledge, from the previous application as a whole.’

Thus, the same standard that is applied for assessing novelty is now also to be used in consideration of priority. Consequently, it follows that if an applicant wishes to obtain the earliest possible priority date for any given embodiment of an invention, a generic claim for which is already contained in a priority filing, a patent application specifically disclosing this embodiment should be filed as soon as the embodiment is identified. Otherwise, the earliest date the applicant can obtain for this embodiment, is the application as filed.

In deciding on this priority issue, one concern of the Englarged Board was to ensure consistency with the legal certainty requirement 7. According to the narrower approach it is no longer necessary to assess whether any modifications are related to the function and effect of the invention, which depends very much on the facts and circumstances of each case and the assessment made by each individual instance.

The impact of G2/98 on disclaimers

Following the decision in G2/98, the Technical Board of Appeal in T323/97 (Disclaimer/ UNILEVER)8 have now confirmed that in light of the above the same considerations for assessing priority are also applicable to the provisions of added matter. In this case, the applicant attempted to introduce a disclaimer9 not having a basis in the application as filed, to establish novelty over an allegedly "accidental" (see recent decision T596/96 - Pro-liposome/PHARES PHARMACEUTICAL)10 disclosure. It had been common practice during prosecution of European patent applications to distinguish over novelty only disclosures, such as an Article 54(3)11 document, by using a disclaimer in the claim to exclude only from its scope that subject matter contained in the prior art disclosure. This will now no longer be possible unless the specific language of the disclaimer itself can be found in the application as filed. The use of disclaimers is considered inconsistent with the principle of legal certainty. With a claim including disclaimer language it is often difficult to assess with any degree of certainty whether or not every individual embodiment of the invention embraced within the scope of the claims involves a technical contribution or solves the same problem associated with the prior art. Furthermore, in view of the fact that any disclaimer introduced during prosecution is unlikely to have basis in the priority document, the new claim will lack priority. In the case where the prior art which necessitated the disclaimer is an Article 54(3) citation, which can be considered for novelty purposes only, the disclaimer may, in fact, now render the document relevant for the consideration for inventive step, since the claim to priority will have been rendered void.

The implications of G2/98 on priority application filings

The new priority requirements identified above will have an enormous impact on patent filing strategies for applicants involved particularly in evolving technologies. Such filing strategies will have to take into account that, unless there is a specific disclosure in a priority application of an obvious modification, a claim in a later filed European filing application to such modification will not be entitled to the original priority date. It is likely that priority applications will become considerably more detailed in the future as applicants strive to identify every possible alternative to ensure there is no loss of priority thereto, should it become necessary to rely on such a feature during the course of the prosecution of the ultimately filed application.

Exact disclosure in the priority document

Clearly, the usual filing process needs to be reconsidered. Traditionally, for priority purposes, applicants tended to rely on a single early application defined rather broadly in order to "encompass" all possible features eventually claimed in the later application. This must now be completely reconsidered in that only features directly and unambiguously derivable from the earlier application can have the benefit of priority claim. A general disclosure "encompassing" specific features does not necessarily disclose such features. For instance, an improvement is not necessarily derivable from the general disclosure of the basic device or method. Under such circumstances, it is unlikely that the improved embodiment can benefit from the priority date of the more general disclosure. This is apparent from existing European Patent Office decisions where the novelty approach was adopted. In T1090/9212, it was held that priority for two specific features could not be claimed from a prior application describing these features in more general terms.

It will also be highly desirable to indicate in the priority document as many fallback positions as possible in order to provide support for any specific embodiments claimed in the later application. This applies in particular to selected individual compounds, preferred parameter ranges such as in respect of homology degree, hybridisation conditions, process conditions (temperature, pressure...), and all preferred, isolated and combined embodiments.

Multiple filings and multiple priority claims

Consequently, it will now be necessary and appropriate during the priority year to file a number of priority applications directed to new improvements or specific embodiments or even obvious modifications not disclosed in the basic application. Priority from all of the applications filed within the priority year would then be claimed when filing the consolidated final European application. Thus, the priority period should be considered as a period for active filing of patent applications each of which includes more information which may be important for the invention eventually claimed in the consolidated application.

However, it is important to keep in mind that multiple priorities cannot necessarily apply to final applications comprising at least one independent claim defining a combination of features. As previously laid down by the Enlarged Board of Appeal in Opinion G3/93 (Priority Interval)13, such a claim can only have a single effective date. If multiple priorities are claimed, the effective date of the claim is the filing date of the earliest application that by itself describes all features of the claims, that is the filing date of the application itself, if each of the multiple priority applications only discloses individual features.

The issue of selections inventions

G2/98 makes it clear that priority claims will not be acknowledged if selection inventions, that is, typically, the choice of individual entities from larger groups or of sub-ranges from broader ranges of numerical values, are considered "novel" over the contents of the priority application (see point 8.4 of the Reasons for the Opinion). T77/97 (Taxoides/RHÔNE POULENC)14 is a representative example in the field of pharmaceuticals. In this case, priority was not granted for a specific chemical compound since it was not individually disclosed as such in the priority document. Merely, it was the result of a selection within a group of 4 possible compounds disclosed in the priority application.

The Board’s view in T77/97, was that:

if specific combinations are envisaged, they must be specifically disclosed by the priority document in order for priority not to be challenged ... Although there is no doubt that the priority document does indeed describe a very narrow group as preferred, it does not, however, draw a distinction between the four compounds of that group and nor does it specify that the formula ... must be considered an abridged formulation of a list or table indicating four individual chemical compounds

(see points 7.1 and 7.3 of the Reasons for the Decision). This is representative of the extent of disclosure required for priority. Similarly, in decision T301/87 (Alpha-interferons/BIOGEN)15 concerned with a biotechnology application in respect of Alpha-Interferon, it was not accepted that the mere reference to a specific DNA sequence fully contained in a deposited plasmid could establish, by implication, priority for a component part of the sequence, because this could not be envisaged directly and unambiguously as such and required considerable investigation to reveal its identity (see point 6.3 of the Reasons for the Decision).

Priority applications covering chemical compounds should therefore include lists or tables of individual compounds of interest, specifically identified, in addition to the general formula and the lists of definitions generally used for each substituent (so called "Markush" language).

Errors in priority documents may invalidate the right of priority

G2/98 will create particular difficulties in those cases where it is found that priority documents contain errors in respect of the disclosure from which priority is sought. If the claimed feature is not directly and unambiguously derivable from the faulty prior disclosure (for instance if the error is not obvious and immediately correctable by the skilled reader), this will result in the loss of the priority right for that specific feature. A decision along those lines was provided in T923/92 (human tPA/GENENTECH)16 where priority for an amino acid sequence was refused on the ground that the sequence claimed in the later application was distinct from that disclosed in the priority document. Specifically, the sequence of human tPa as claimed in the later application differed by only three amino acids from the sequence disclosed in the priority document. It was the Board’s view that:

the correct sequence cannot be derived directly and unambiguously from the priority document, in which different sequences are reported ... and a large amount of investigation is required in order to reveal their true identity.

It was held that:

...the primary amino acid sequence of a protein (or the nucleotide sequence of a DNA) constitutes a true technical feature and relying on a given sequence rather than on another one for the definition of the subject matter of an invention in a claim makes a critical difference. Thus, claim 1 is not entitled to the first or the second priority date because it does not relate to the same invention as disclosed in the respective priority documents

(see points 14 and 16 of the Reasons for the Decision).

As a result, if an error is identified in a basic application during the priority year it is recommended to file immediately a further basic application containing the correct disclosure. Obviously, at the end of the priority year, priority from both basic applications should be claimed when filing the mature application, with claims directed to both the incorrect and correct sequences.

Publication of the invention after the priority filing may now put validity of the claims at risk

Finally, the strict approach for considering valid priority should be kept in mind each time it is intended to present at conferences or publish as scientific papers the contents of the priority application, before the consolidated European application is filed. The Decision of the Enlarged Board of Appeal in G3/93 (Priority Interval)17 decided that disclosures during the priority interval can be used to invalidate claims that were added to the ultimately filed application and which cannot claim the priority date.

If the disclosure of the invention which will be claimed in the later consolidated European application is different from that originally disclosed in the priority application, by, for example, including reference to obvious modifications, this may result in:

- at least a partial loss of priority right for that subject-matter claimed in the European patent application which is not directly and unambiguously derivable from the priority application; and

- as a result, lack of either novelty or inventive step for that subject-matter over the intermediate publication even if made by the inventor himself.

Therefore, it is essential now to ensure that any publication will not go any further than the disclosure of the priority application. Alternatively, an additional priority application related to the exact content of the publication should be filed before the publication date.

The stricter approach taken by the EPO clearly adds an additional burden to the applicant and his representative to specifically disclose each individual embodiment in the priority application, or, if this is not possible by the time the priority application is filed, to file further priority applications to secure specific disclosures for each individual embodiment not disclosed in the first priority application. This will have serious cost implications for applicants and the benefits of filing any new priority applications will need to be considered in that context.

The extra benefits of G2/98

However, applicants should also be able to take advantage of the new approach in a number of ways. In particular, it will be more difficult to lose priority on the basis that the application from which priority is claimed is not the earliest disclosure18 in respect of that feature of interest.

In the Figure 1, an application (PR1) is filed by the inventor in a Convention country more than a year prior to the filing date of the European application (EP) and discloses variant (A). (A’) is disclosed in the application (PR2) from which priority is claimed by EP and A’ is an obvious variant of A. In accordance with Article 87 EPC, the priority right will be lost if A’ is considered to be the same invention as A if both PR1 and PR2 were filed in the same country. According to the new "same invention" requirement it should be possible to argue that A’ is not directly and unambiguously derivable from A, in order to argue that PR1 does not disclose the same invention and that PR2 is actually the first application disclosing A’.

Similarly the narrower interpretation of the "same invention" requirement can also be used to the benefit of the applicants, to allow them to delay European application filings and to secure up to a further 12 months protection for their invention. In particular, in the circumstances identified above, A’ is an inessential modification of A and is discovered within a year from the filing date of the basic application disclosing A:

PR1

filed at date s

discloses A

PR2

filed at date t

discloses A

EP priority, PR1 or PR2?

filed at date s + 12 months or t + 12 months? claims A

If a broad approach were taken for assessing priority for EP, PR1 would be the first application disclosing the same invention (A’ being an inessential modification of A) as that claimed by EP. According to Article 87 EPC, EP would then have to be filed within twelve months from the filing date of PR1 (s + 12 months).

But, according to the strict approach now taken, A’ is to be considered as a different invention from A for the purpose of assessing priority. As a result, an EP application can be filed up to 12 months after the filing date of PR2 (t + 12 months). The European application filing can therefore be deferred and the term of protection correspondingly extended for a further year. This is of particular importance in the pharmaceutical field where, due to long development time, the final product is eventually marketed near the end of the patent term. Accordingly, the pharmaceutical industry will be able to secure longer protection for their drugs thereby preventing third parties from entering the market for longer.

Conclusion

One of the significant implications of the Opinion G2/98 of the Enlarged Board of Appeal is that it will permit applicants to extend their patent life by implementing a strategic filing policy which, in the pharmaceutical field, can have significant monetary benefits. The Enlarged Board of Appeal have seemingly increased the risk of losing the priority right for subject matter not directly and unambiguously derivable from the priority application, unless the required disclosure is secured in the priority document(s) causing increased costs for the applicant for drafting either appropriate comprehensive applications or filing multiple priority applications. The strict approach taken should increase certainty for third parties as to whether priority right is validly claimed or not, when assessing validity of European patents.

While the Enlarged Board of Appeal is definitely binding on the EPO as far as the grant process is concerned, it remains to be seen whether National Courts will also follow this opinion and will harmonize their practice when ultimately deciding on the validity of granted European patents.

1. Opinion of The Enlarged Board of Appeal G2/98 ("Requirement for claiming priority of the "same invention"), dated 31 May 2001 (OJ EPO, 2001, 413)

2. The Paris Convention for the Protection of Industrial Property of 20 March 1883, revised at Brussels (14.12.1900), Washington (02.06.1911), the Hague (06.11.1925), London (02.06.1934), Lisbon (31.10.1958) and Stockholm (14.07.1967) . To give rise to priority right, the earlier application must have been filed in or for any state party to the Paris convention. Worth noting is that in the UK, with effect from 29 July 1999, the priority right has been extended on the same terms from member states of the Paris Union to all member states of The World Trade Organisation ("The WTO"): Section 90 of the Patents Act 1977 provides for countries, by Order in Council, to be declared "Convention countries" for the purposes of the claiming of priority under Section 5. Priority from applications filed in Convention countries can therefore be claimed for by UK applications.

3. The European Patent Office which as such is not a member of the Paris Convention can not implement the existing Paris Convention’s provisions. A similar parallel legislation in respect of the priority right has thus been included in the European Patent Convention. Articles 87 to 89 EPC provide a complete, self-contained code of rules of law on the subject of claiming priority for the purpose of filing a European patent application.

4. According to Article 54(3) EPC, the state of the art also comprises the content of European applications filed earlier than, but published on or after the date of filing of that application being examined, to the extent that the earlier and later applications designate the same state(s).

Article 89 EPC provides that if the application claims priority, the priority date replaces the filing date for that subject -matter in the application which corresponds to the priority application.

5. T81/87 Preprorennin/COLLABORATIVE, OJ EPO 1990, 250

6. T73/88 Snackfood/HOWARD, OJ EPO 1992, 557

7. See G2/98 - point 8.3 of the Reasons for the Opinion.

8. See T323/97 Disclaimer/UNILEVER (OJ EPO 2002, to be published) - points 2.3 and 2.4 of the Reasons for the Decision. Having considered the earlier decisions approving the practice of disclaimers, the Board could find "no argument which would justify the maintenance of this practice in the light of the Enlarged Board of Appeal’s Opinion G2/98".

9. A "disclaimer" is an amendment made to a claim by the introduction of a "negative" feature with the effect of excluding an embodiment of the claimed invention which is disclosed in a novelty destroying prior art disclosure.

10. T596/96 Pro-liposome/PHARES PHARMACEUTICAL (unpublished, dated 14 December 1999) - Disclaimers used to be allowed by the European Patent Office when the disclaimed piece of prior art could only be relevant to novelty and not to inventive step. (i.e) "The novelty destroying document must disappear from the prior art field to be taken into consideration" (see point 2.2)

11. See Note 4 above

12. T1090/92: unpublished dated 8 December 1994; see points 5.2, 5.3 and 5.5 of the Reasons for the Decision.

13. Enlarged Board of Appeal Opinion G3/93 Priority Interval, OJ EPO 1995,18

14. T77/97 Taxoides/RHÔNE POULENC, EPOR 1998, 256. The decision concerned the examination of the priority for a specific compound specifically claimed as such in the European application but which was disclosed by means of a general formula and the selection of 2 varying substituents among 2 lists of 2 possibilities each in the priority document. The Board held that the compound resulted from the combination of 2 substituents which was not specifically disclosed in the priority application. Therefore, priority was not acknowledged.

Although this case was decided before the Enlarged Board of Appeal’s opinion referred to herein, it involved the strict approach for determining valid priority claim and is therefore regarded as being representative of the recent developments.

15. T301/87 Alpha-interferon/BIOGEN, OJ EPO 1990, 335

16. T923/92 Human tPA/GENENTECH, OJ EPO 1996, 564

17. see Note 13 above.

  • According to Article 87(1) EPC, the application of which priority is claimed must be the first application in the sense that it must be the application describing for the first time the subject matter of the European application claiming the priority.
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