Double patenting occurs where the same invention is protected by more than one patent, and the UK is one of many countries having provisions to prevent this. Although the European Patent Convention (EPC) does not explicitly prohibit double patenting, it is an accepted principle under European patent practice that double patenting is not allowed. However, the definition of the “same invention”, and the relevant provision applicable in certain situations, is not always clear.
Section 18(5) of the UK Patents Act 1977 (UKPA) provides that, where two or more UK national patent applications are for the same invention, and have the same priority date and the same applicant, then a patent may be refused for one or more of those applications. In addition, Section 73(2) of the UK Patents Act 1977 provides that the UK Intellectual Property Office (UKIPO) may revoke a UK national patent if both a UK national patent and a European patent (designating the UK) have been granted for the same invention.
Although the EPC does not have any explicit provisions prohibiting double patenting, European case law provides that double patenting is prohibited on the basis that an applicant has no legitimate interest in the grant of a second patent for the same invention.
(i) Definition of “the same invention”
- Applications/patents under the UKPA
Sections 18(5) and 73(2) of the UKPA do not define what is meant by the term “the same invention”, but the Manual of Patent Practice (MOPP) states that the test is the same for both Sections. The MOPP also states that these Sections embody the principle that the same monopoly cannot be granted twice. Therefore, these provisions cover situations where (1) the applications or patents in question contain claims (including dependent claims) explicitly including all of the same features and (2) the claims differ in their wording but their scope does not differ “in substance”. Accordingly, UK examiners must consider both the independent claim and dependent claim(s) in order to determine whether two patents or applications claim the same combination of features. Thus, double patenting is not concerned with only the independent claim(s) of a patent or application.
UK case law indicates that double patenting occurs where, even if the wording of the claims in question is different, the result of the claims is the same. For example, in Maag Gear Wheel and Machine Co Ltd’s Patent  PRC 572, it was held that there was double patenting between a UK patent and a European patent (UK) because an additional feature explicitly recited in the European claims was implicitly present in the UK claims (the UK claims were not explicitly limited to this additional feature). Similarly, in IBM Corporation (Barclay and Bigar’s) Application  RPC 283, it was held that the claims of two patents did not differ in their result, because the further limitation of a feature in the claim of one patent was held to be implicit in the claim of the second patent in order for the invention to work.
However, where the claims of two patents or applications only partially overlap, it is likely that there will be no double patenting. In particular, in Kimberley-Clark Worldwide Inc.’s Patent (BL O/279/04) it was held that a claim to features A+B was not the same as a claim to only feature A. The UKIPO considered that the inclusion of feature B in the second patent led to sufficient difference between the two claims and that, therefore, there was no double patenting.
- Applications under the EPC
The European Patent Office’s (EPO) Guidelines for Examination do not provide any clarification of the definition of the term “same invention”, except to say that there is no double patenting if the claims do not relate to the same subject matter. However, European case law has established that a mere (i.e. partial) overlap does not prejudice the grant of two patents (e.g. T 1780/12, T 2461/10, T 877/06). Accordingly, it was held that there is no express or implicit provision in the EPC which prohibits the presence of an independent claim which recites all of the features of a claim in second application combined with an additional feature (T 587/98). T 1391/07 considered that this partial overlap meant that some, but not all, embodiments notionally encompassed by one of the claims would also be encompassed by the other claim in question. Thus, as in the UK, a claim reciting feature A does not preclude a claim in a second application from reciting features A+B.
Of particular interest to applicants in the field of medicine, second medical use claims (i.e. reciting a specific substance for use in the treatment of a specific condition or disease) are considered, under both UK patent practice and European patent practice, to differ in substance from Swiss-type claims (i.e. reciting the use of a specific substance in the manufacture of a medicament to treat a particular disease or condition). This is because Swiss-type claims are purpose-limited process claims, and, therefore, include a step of manufacturing a medicament, while second medical use claims are purpose-limited product claims and do not include such a manufacturing step. Thus, there can be no double patenting between second medical use claims and Swiss-type claims under both UK and European patent practice.
Thus, in view of the similar interpretation of the term “same invention” in both Europe and the UK, patentees should be able to avoid double patenting in either territory by making sure that the claims of the second application recite a combination of features which is not present in the claims of the first application, whether explicitly or implicitly.
ii) Double patenting situations
There are several situations in which double patenting may occur and which are covered by the UKPA or European case law, as follows:
- two national UK patent applications (S. 18(5) UKPA),
- a national UK patent and a European patent (UK) (S. 73(2) UKPA), and
- two co-pending European applications (European case law).
However, there are no clear provisions or case law relating to the grant of two European patents (UK), for example, where one European patent designating the UK is already granted and a second European application designating the UK is pending or accepted for grant. In particular, Section 18(5) of the UKPA refers only to “two or more applications” (i.e. national UK applications) and Section 73(2) UKPA refers only to “a patent under this Act and a European patent (UK)” (i.e. a national UK patent and a European patent designating the UK). Section 77 of the UKPA provides that a European patent (UK) is treated for the purpose of the UKPA as if it were a national UK patent, such that one might interpret Section 73(2) as relating also to two European patents (UK). However, it appears that the European patent (UK) is not, in fact, treated as a national UK patent for the purpose of Section 73(2) UKPA. Thus, Section 73(2) is relevant only to double patenting between a national UK patent and a European patent (UK), and is not applicable to two European patents (UK). The UK Intellectual Property Office (UKIPO) has confirmed this interpretation with the author’s colleague. Consequently, the UKIPO will not object to a second European patent (UK) which relates to the same invention as a first European patent (UK).
It should be noted, however, that there is still a risk that the EPO will raise an objection that there is double patenting between a granted European patent and a pending European application as this situation is relevant to the principle under European patent practice that an applicant has no legitimate interest in the grant of a second patent for the same subject matter as a first granted patent. Thus, although there is no explicit mention of double patenting between two granted European (UK) patents, or a granted European (UK) patent and a pending European application, in either UK patent law or European case law, the patentee should be aware that this does not prevent objections being raised by the EPO.
In summary, both the UKIPO and the EPO consider that there is no double patenting if the claims relate to different subject matter, and this is interpreted to mean that the claims of the two patents or applications only partially overlap. In other words, where some embodiments of the invention are covered by the claim of one patent or application but not the claim of another patent or application, there is no double patenting. In addition, there is no provision under UK law to object to double patenting between two European patents designating the UK, but the EPO may well raise such an objection during prosecution of the second European application.