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Claiming Priority: Pitfalls and Poisonous Priorities

Date: 5 October 2013


Claiming priority is of major importance to the practice of patent law. A string of recent cases have demostrated this - several recent cases have shown patents revoked for want of priority. Most recently, the UK courts have made a U-turn on how strictly must a claimed invention be “the same” as that of its priority document if a claim to priority is to be valid. Here we assess the implications of this decision.


Back in Autumn 2004 Patent issues, we wrote that the “strict” same-invention rule laid down by the EPO Enlarged Board of Appeal in Decision G2/98 was not being applied so strictly by the UK Court of Appeal. Unfortunately for patentees, there have been two subsequent decisions of the same court that have significantly changed the tone. This is now proving to be a graveyard for patents, as illustrated by recent cases in the ongoing mobile phone wars and coffee wars. Samsung had three patents revoked on these grounds in its battle against Apple, and Nestle Nespresso similarly lost an important patent in the same way.


The need to claim priority in the Samsung cases was acute, as Samsung had disclosed its inventions to standards committees shortly after filing the initial applications. Those disclosures became novelty-destroying when the Patents Court ruled that Samsung had changed the specifics of the invention being claimed and was not entitled to priority.


The situation for Nestlé Nespresso was still more alarming. The Patents Court concluded that the priority document itself was novelty-destroying prior art. How can that be? If the priority document discloses the claimed invention, surely it must support the claim to priority? Not necessarily – not when the invention claimed in the later application is broader than that described in the earlier application. That creates a “poisonous priority” situation in which the later claimed invention is not entitled to priority but the earlier described invention falls within the scope of the claims and the claims are therefore not new.


Did the law change, and if so, how?


Back in 2004, Jacob LJ (as he then was) seemed to give a pragmatic and flexible approach to claiming priority. He ruled:


“when features A+B+C are disclosed [in a priority application], a lot must turn on what they actually are. Some inventions consist of a combination of features – the invention consists in the very idea of putting them together. In other cases that is simply not so – the features are independent one from the other. Whether, given a disclosure of A+B+C, there is also a disclosure of A or B or C independently depends on substance, not a formula. The ultimate question is simply whether the skilled man can derive the subject-matter of the claim from the priority document as a whole.”


Unfortunately, this was embellished by Kitchen LJ in Abbot Laboratories v Evysio Medical Devices [2008] EWHC 800 (Pat):


"the important thing is . . . whether the disclosure as a whole . . . gives the skilled person what is in the claim whose priority is in question. I would add that it must “give” it directly and unambiguously."


So the dreaded words “directly and unambiguously” have crept back into the test for claiming priority. These words are the bane of a European patent attorney’s life, as they represent the ultra-strict test applied by the EPO when assessing added subject matter under Article 123(2), EPC. European examiners have a tendency, for example, to consider any amendment that might remove an ambiguity as adding subject matter. Even the addition of a comma can give rise to objection (see Examiner Eats Shoots and Leaves in Autumn 2011 Patent issues). Yet the Court of Appeal was clear in its decision in Unilin that the approach to claiming priority is not so formulaic (see Spring 2004 Patent issues):

“Whether, given a disclosure of A+B+C, there is also a disclosure of A or B or C independently depends on substance, not a formula. The ultimate question is simply whether the skilled man can derive the subject-matter of the claims from the priority document as a whole.”

What then, if anything, is the difference between the “same invention” test for claiming priority and the “directly and unambiguously derivable” test for added subject matter?


This is a question best answered by some examples. We have four. The first three are Samsung’s. These were considered in two separate judgements delivered on 7 March 2013, referred to as “Judgement on the 726 and 675 patents” and “Judgment on the 404 patent”. We will call them simply “Samsung I, II and III”.The fourth is the Nestlé case, delivered on 22 April 2013 under the name “Nestec”.



Samsung’s ‘726 patent related to an encoder in which frames were combined into super-frames for turbo encoding. The number of frames to be combined depended on a “quality of service (QoS) parameter”. An example of a QoS parameter was data rate. By contrast, the priority application described that the number of frames to be combined in a super-frame depended on message information, which in turn was described as a service type and a data rate. Some services types (like data) can tolerate longer time delays while others (like voice) require short time delays but can tolerate higher bit error rates.


By referring to QoS parameters, the claim was more general. There was no “direct and unambiguous disclosure” that anything other than data rate, input frame length and service type should be used to determine the number of frames to assemble. Had the patent draftsman over-egged the pudding by broadening the claim? Or had there been some poor translation in the priority application from the original Korean? It matters not. The patent was holed below the waterline.



Samsung’s ‘675 patent was a more clear-cut case of no entitlement to priority. The patent claim called for matching transport channel frames to physical channel frames using frame matchers that would determine a number of filler bits to be inserted. Filler bits allow for cases where there is a non-integer ratio between transmission time intervals (TTIs) for an input frame and a radio frame. But the priority application was silent on how the apparatus works in such a case and made no mention of filler bits at all.



In the case of the Samsung ‘404 patent, the patent related to an improvement on High Speed Downlink Packet Access (HSDPA) introduced in 2002 in 3GPP Release 5. The improvement concerned High Speed Uplink Packet Access (HSUPA). UMTS Release 5 defined a number of existing uplink channels and the patent concerned allocation of I/Q channels1 in different scenarios of such existing “legacy” channels. The priority document described a scheme for allocating I/Q channels and OVSF2 codes and gave a table of examples, the first line of the table giving a specific example of an I/Q channel allocation in the case of a single transmittable legacy channel. Samsung’s claim was focussed on that one example and was silent on allocating OVSF codes.



Turning to the Nestec case, this is an interesting for reasons beyond the dry question of claiming priority. In particular, Nestle’s “Nespresso” capsules were protected by patents, which expired in May 2011, but this did not stop them from suing Dualit for contributory infringement through the supply of coffee capsules. They failed on those grounds (see below) and they also failed for lack of priority.


The reason Nestle’s patent was not entitled to priority is because its claims were broad enough to cover three ways of housing a coffee capsule and three ways of moving it to its extraction position: (i) entirely within a fixed part of the machine or (ii) entirely within a moving part or (iii) divided between the fixed and moving parts.


Only the first arrangement was described in the priority document. The Court considered the first and second options to be clearly defined alternatives. If that were the end of the matter, the claim would be entitled to partial priority for the supported alternative. But the Court took the view that the third option covered a wide range of different arrangements (everything not covered by the first and second options). Contrary to Unilin, it was not a clearly defined alternative. The claim was not entitled to priority.


In terms of the three possible ways of moving the capsule, the axis of the capsule is illustrated here by the upper dotted black lines and the extraction axis is shown by the lower dotted blue lines:




The Court interpreted the patent claim as requiring movement of the capsule both downwards and along from the intermediate position to the extraction position. This is the third arrangement. Such tilting arrangements were expressly described in the specification and the Court ruled that the skilled reader “would appreciate that claim 1 included them”. It was therefore important that the third arrangement was entitled to priority. The parties agreed that the priority document disclosed the first arrangement, but the third arrangement was not expressly disclosed. Dualit contended that this alone meant that claim 1 was not entitled to priority. Nestec contended that it was implicitly disclosed.


After considering whether there might be any incidental tilting of the capsule to give rise to an inclined axis, the Court concluded that tilting of the capsule in the arrangements described in the priority document was not inevitable and certainly not intentional or advantageous. The claim was not entitled to priority.


Poisonous Priority


In Nestec’s case, the loss of priority was inherently fatal even if there had been no other intervening publication, because the contents of the priority document itself became part of the state of the art under section 2(3) of the Patents Act 1977 (corresponding to Article 54(3) EPC). The patentees argued that the claims cannot simultaneously lack priority from, and be anticipated by, the priority document, but the court ruled that this is legally possible and, since the priority document disclosed arrangements having all the features of the relevant claims (which were broader than the disclosure of the priority document and therefore not entitled to priority) they lacked novelty over the disclosure of the priority document.




Our advice has not changed in light of these decisions. It is merely of greater importance than ever:


  • Don’t assume that the filing of a priority application means it’s safe to publish. Only if the invention is not going to be developed further is it safe.
  • Be very wary about tinkering with the scope of the claims when filing in the UK or the EPO based upon an earlier priority application.
  • Generic expressions will not be supported by specific examples, and it is better not to rely on the G2/98 test for awarding multiple priorities for generic expressions that comprise a limited number of clearly defined alternatives. It is better to call out the specific alternatives so that each has its respective priority date. The word “or” is acceptable in European and UK drafting practice.
  • It is safe to add further embodiments, examples or claims (dependent or independent) to the later application, provided there is unity of invention with the claims that are entitled to priority, but it is not safe to broaden the claims to encompass the new embodiments or examples. New claims to further embodiments or examples will not benefit from priority and indeed the further embodiments or examples will give rise to a new right of priority that can be claimed later (Paris Convention Article 4F).


The meticulous analysis to which the EPO is prone focuses solely on the law of the office in which the application claiming priority is filed and takes no account of the law of the state of first filing. It does not ask what would the applicant have been entitled to claim under the laws of that state. Perhaps such a question is out of place – can there be different rules for different applicants? Without international consensus on the issue, a lamentable situation exists in which any applicant in any state must draft his or her initial application with such foresight and thoroughness that no amendment is required before re-filing and claiming priority.


Parallel GB and EP patents


The nightmare scenario of a poisonous priority document also raises its ugly head in the situation of parallel applications of different scope – e.g. parallel GB and European patent applications. It is not uncommon to file a GB application and, a year later, file an EP with a few more embodiments and perhaps a broader claim 1. The EP application of course designates GB. But the broader claim of the EP application will not benefit from priority (and this may go unnoticed, because the EPO does not examine the priority claim unless there is intervening prior art). The GB priority document is prior art in GB for the purposes of section 2(3), so the EP application will be invalid in GB. In these circumstances it may be important to:


  • Prosecute the GB application to grant, with clearly defined difference in scope to the EP application.
  • Make sure the EP clearly demarks, in the claims, the parts that are entitled to priority. That way, some parts are entitled to priority and are not anticipated by the priority document, and others are not entitled to priority, but are not disclosed in the priority document. The word “or” can be used as necessary.
  • Or withdraw the GB application before it proceeds to publication.


For more help and advice, please contact Hugh Dunlop.