Double patenting is the granting of two patents for a single invention, to the same proprietor and in the same country or countries. According to the European Patent Office, it is an accepted principle in most patent systems that two patents cannot be granted to the same applicant for one invention. However, the threshold for double patenting varies from jurisdiction to jurisdiction.
In Canada, the Supreme Court has indicated that there are two branches of double patenting. The first branch of double patenting ("same invention" or "novelty-type" double patenting) requires that claims of two issued patents must not be identical or conterminous. The second branch of double patenting (termed "obviousness-type" double patenting) requires that claims of two issued patents be "patentably distinct" (non-obvious) in view of one another. Even applications that expire on the same day may be open to double patenting challenges, as the courts have viewed possession of two patents for one invention to constitute an undue benefit.
Technically, double patenting can only exist between issued patents. However, double patenting objections may be raised by an examiner during an application's pendency. The position of the Patent Office is that such objections are raised as a courtesy; examiners are under no obligation to identify double patenting situations during prosecution. Canadian practice differs significantly from U.S. practice on this front, in that, once a double patenting objection is encountered, there is no statutory provision for terminal disclaimer in the Canadian Patent Act. Thus, terminal disclaimer is not available to overcome double patenting objections. Instead, the applicant must demonstrate (by arguing or amending the claims) that the claims are patentably distinct in view of those of the co-pending application.
Divisional applications filed voluntarily may be susceptible to attacks on the grounds of double patenting. However, where a divisional is forced by the Patent Office during prosecution (i.e. to overcome a unity of invention objection), the Supreme Court of Canada has indicated that such an application and its parent should not be open to double patenting challenges.
European Patent Convention
The European Patent Convention (EPC) does not contain any specific provisions relating to double patenting. The European Patent Office's (EPO) Boards of Appeal have however addressed the issue in several cases.
In 2000, the EPO's Technical Board of Appeal 3.5.2, in case T 587/98, held that, "There is no express or implicit provision in the EPC which prohibits the presence in a divisional application of an independent claim -explicitly or as a notional claim arrived at by partitioning of an actual claim into notional claims reciting explicit alternatives-which is related to an independent claim in the parent application (or patent if, as in the present case, it has already been granted) in such a way that the 'parent' claim includes all the features of the 'divisional' claim combined with an additional feature."
Obiter dictum in G 1/05 and G 1/06
- "the principle of prohibition of double patenting exists on the basis that an applicant has no legitimate interest in proceedings leading to the grant of a second patent for the same subject-matter if he already possesses one granted patent therefor.
The Board therefore accepted the practice of the EPO "that amendments to a divisional application are objected to and refused when the amended divisional application claims the same subject-matter as a pending parent application or a granted parent patent." 
Soon after, in July 2007, the Technical Board 3.3.07 in case T 307/03 followed the Enlarged Board of Appeal reasoning and held that a "principle of prohibition of double patenting" was applicable under EPC. It additionally held that the double patenting prohibition was also applicable for a "later claim more broadly formulated" (compared to a claim already granted in the parent application). The Board notably based its reasoning on the wording of Article 60 EPC according to which "[the] right to a European patent shall belong to the inventor or his successor in title". In other words,
- "[once] a patent has been granted to the inventor (or his successor in title) this right to a patent has been exhausted, and the European Patent Office is entitled to refuse to grant a further patent to the inventor (or his successor in title) for the subject-matter for which he has already been granted a patent."
The Board in case T 307/03 explicitly disagreed with the apparent conclusion of earlier decision T 587/98 that there would be no basis in the EPC prohibiting "conflicting claims".
In case T 307/03, which related to a pending divisional application of a granted European patent, three requests were pending. In the main request, the subject-matter of claim 1 corresponded exactly to the subject-matter of claim 3 when dependent on claim 1 of the granted European patent (that is, the patent granted on the parent application). The claim was therefore objected for double patenting and the main request was not allowed into the proceedings. The first auxiliary request was not allowed into the proceedings for essentially the same reasons. Finally, in the second auxiliary request, the subject-matter of the main claim encompassed by the subject-matter of claim 3 of the parent application as granted. This request was also not allowed into the proceedings on the ground of double patenting. The divisional application was therefore refused.
In case T 1391/07 (November 2008), the Board 3.4.02 held that a double patenting objection did not arise when the claims of two applications only overlap, in such a manner that the scope of protection sought by the invention claimed in the divisional application was notionally different from the scope of protection conferred by the claims of the granted parent patent. In other words, the Board held that when there was a partial overlap in the respective scopes of protection:
- "there is at least one technical feature in each of claim 1 [of the divisional application] and claim 1 of the granted parent patent clearly distinguishing the subject-matter of the respective claim from that of the other one of the claims, and that these distinguishing features are such that the scope of protection sought by the invention claimed in the [divisional] application is notionally different from the scope of protection conferred by claim 1 of the granted parent patent",
this did not lead to a double patenting objection. This was found by the Board 3.4.02 to be in line with decisions T 118/91, point 2.4.1 of the reasons, T 80/98, point 9, T 587/98 (OJ EPO 2000, 497), point 3.3, T 475/02, point 8.6, T 411/03, point 4.2, T 425/03, point 4.2, T 467/03, point 4.2, T 468/03, point 4.2, and T 579/05, point 2.2, and the obiter dictum in decisions G 1/05 and G 1/06.
Not a ground of opposition (T 936/04)
- "[it] is within the discretion of the instances of the EPO to raise the objection in opposition or opposition appeal proceedings against proposed amended claims, but this should be done only in clear cases. The purpose behind the principle of prohibition of double patenting is to avoid unnecessary duplication of effort, and not to impose on the instances of the EPO an obligation to make a complex comparison between the case before them and the claims that may have been granted in some other proceedings."
Since July 2004, the issue of double patenting provides one possible ground for revocation of all Singapore patent applications. Under section 80(1)(g) of the Singapore Patents Act, a patent may be revoked if "the patent is one of two or more patents for the same invention having the same priority date and filed by the same party or his successor in title".
|This section requires expansion with: information about Marley's Patent  RPC 231 (UK Court of Appeal). (March 2009)|
- "Where two or more applications for a patent for the same invention having the same priority date are filed by the same applicant or his successor in title, the comptroller may on that ground refuse to grant a patent in pursuance of more than one of the applications."
The United States has two types of double patenting rejections. One is the ‘same invention’ type double patenting rejection, based on 35 U.S.C. sec. 101, which states in the singular that an inventor "...may obtain a patent." The second rejection type precludes what is referred to as "obviousness type" double patenting. The "nonstatutory-type" double patenting rejection is based on a judicially created doctrine grounded in public policy and primarily is intended to prevent prolonging the patent term, by prohibiting claims in a second patent that are obvious variations on claims in an earlier patent. This type of double patenting rejection only requires a single common inventor, and does not require common ownership. The terminology "not patentably distinct" or "distinguished" from the earlier claims is often used to describe "obviousness type" double patenting.
Double patenting rejections are commonly seen in continuing patent applications. Such rejections can usually be overcome if the patent applicant files a terminal disclaimer and disclaims the term of the later-issuing patent that extends beyond the term of the earlier patent. The disclaimer may be filed, however, only if the same inventor or combination of inventors is named in both patents. Even then, the rejections may stand because of unfavorable facts. The disclaimer is not an admission that the invention is the "same", and will not create an estoppel or contractual obligation when the inventor has made admissions about "the invention".
References and notes
- Guidelines for Examination in the EPO, section g.iv.5.4 : "Double patenting".
- Whirlpool v. Camco, 2000 SCC 67, 9 C.P.R. (4th) 129
- GlaxoSmithKline Inc. et al. v. Apotex Inc. et al. (2003) 234 F.T.R. 251, 27 C.P.R. (4th) 114 (F.C.T.D.)
- Re Orasure Patent Application (2009) 79 C.P.R. (4th) 205 (PAB)
- Consolboard Inc. v. MacMillan Bloedel (Saskatchewan) Ltd.  1 S.C.R. 504, 56 C.P.R. (2d) 145 at 169 (S.C.C.)
- T 307/03, reasons 2.3.
- Decision of 12 May 2000, Case Number: T 0587/98 - 3.5.2, reasons 3.7.
- Double Jeopardy And European Patents, Boult Wade Tennant web site, April 2001, or Neil Thomson, Double jeopardy and European patents, Managing Intellectual Property, April 2001, p. 50.
- T 1391/07, reasons 2.5. "the Enlarged Board of Appeal has recently endorsed by way of obiter dictum in decisions G 1/05 and G 1/06 the practice of the EPO in this respect (see point 13.4 of the reasons: "The Board accepts that the principle of prohibition of double patenting exists...")
- Decision G 1/05 of the Enlarged Board of Appeal of the EPO, Reasons 13.4. (see also OJ EPO 2008, 271 and 307).
- Decision T 307/03 of the Technical Board of Appeal 3.3.07 of 3 July 2007 (pdf), to be published in the Official Journal of the EPO. See also T 936/04, reasons 2.1, "[The Board 3.3.07] has applied [the principle of prohibition of double patenting] to refuse a (divisional) application in decision T 307/03 of 3 July 2007 on the basis of requests that involved double patenting over claims already granted in a patent issued on the parent application in that case." The decision was criticised in the literature by D. Harrison and T. Bremi, epi information 2/2009, 64. The decision was also commented on specialized blogs in March 2009, see (French) Laurent Teyssèdre, Interdiction de la double brevetabilité, Le blog du droit européen des brevets, 18 March 2009; David Pearce, Double Patenting at the EPO - a new view, IPKat, 20 March 2009; David Pearce, Derk Visser on Double Patenting, IPKat, 24 March 2009 (including references to the EPC Travaux Préparatoires by Derk Visser).
- T 307/03, Keywords and reasons 5.3.
- T 307/03, reasons 2.1.
- T 307/03, reasons 2.7.
- T 307/03, reasons 3.1.
- T 307/03, reasons 4.1.
- T 307/03, reasons 5.2.
- T 307/03, reasons 5.3.
- Decision of 7 November 2008, Case Number: T 1391/07 - 3.4.02, reasons 2.4, 2.5.
- T 1391/07, reasons 2.4
- T 1391/07, reasons 2.5.
- Decision of 28 July 1992, Case number T 0118/91 - 3.2.1
- Decision of 26 September 2000, Case number T 0080/98 - 3.2.4
- Decision of 21 December 2006, Case number T 0475/02 - 3.3.07
- Decision of 23 February 2006, Case number: T 0411/03 - 3.5.01
- Decision of 23 February 2006, Case number: T 0425/03 - 3.5.01
- Decision of 24 February 2006, Case number T 0468/03 - 3.5.01
- Decision of 10 October 2007, Case number: T 0579/05 - 3.2.02 (French)
- Decision of 24 April 2008, Case Number: T 0936/04 - 3.3.07
- T 936/04, reasons 2.3.
- Joseph Krupa, Lee Chai Lian, Avoid double patenting issues, Managing Intellectual Property, September 2008.
- T 307/03, reasons 2.2.
- Quotation from MPEP 8th Ed., revised July 2008, section 804 “Definition of Double Patenting” publication of the US government
- See In re Hubbell (Fed. Cir. 2013)
- See, e.g., Agrizap, Inc. v. Woodstream Corp., 520 F.3d 1337, 1343-44 (Fed. Cir. 2008). In Agrizap, when the patentee was faced with an obviousness-type double patenting rejection, it "corrected the inventorship for the '636 patent so that both the '636 patent and the '091 patent had the same inventor and filed for terminal disclaimer." According to the Federal Circuit, "This eliminated the '091 patent as a basis for rejection for obviousness-type double patenting." Overcoming the rejection based on the earlier patent was not enough, however, because the commercial embodiment of the patented device (the "Gopher Zapper") had been in public use more than a year before the application for the later patent was filed. Despite the evidence of great commercial success, it could not "overcome the overwhelming strength of Woodstream's prima facie case of obviousness." The later patent was therefore invalid for obviousness under section 103: "This is a textbook case of when the asserted claims involve a combination of familiar elements according to known methods that does no more than yield predictable results."
- See Quad Environmental Technologies Corp. v. Union Sanitary District, 946 F.2d 870 (Fed. Cir. 1991).
- Europe Patent Convention
- Guidelines for Examination in the EPO, section g.iv.5.4 : "Double patenting".
- Guidelines for Examination in the EPO, section c.ix.1.6 : "Claims" (Divisional applications)
- Case Law of the Boards of Appeal (Fifth edition 2006), pp. 287–288, III.F.3. Double patenting
- United States