eu and us approaches towards the double patenting doctrine - ELSA

EU AND US APPROACHES TOWARDS THE DOUBLE PATENTING DOCTRINE
1. INTRODUCTION
JAN LOOSEN 1
The concept of “double patenting” currently is without any doubt a hot topic within both
United States and European patent law mainly thanks to the all in all controversial ruling of
the European Patent Office’s Boards of Appeal (hereafter cited as EPO) in cases T 1391/07
and T 1423/07.
This paper consists of three major parts. Firstly, I will define the concept of double patenting
as well provide a brief overview of its historical development (hereby especially focusing on
United States Supreme Court and EPO cases). Next, I will discuss the so-called standard of
duplicity which in the United States consists of both an identity and a patentability test; on the
same page, I will discuss the European T 1391/07 and T 1423/07 cases. Last but not least, I
will discuss the “terminal disclaimer” principle, a specific legal mechanism constructed by the
US case law (“judge-made doctrine”).
2. WHAT’S IN A NAME? THE CONCEPT OF DOUBLE PATENTING
2.1 Definition
By the term “double patenting” we mean the doctrine that precludes one person from
obtaining more than one valid patent for the same invention or obvious modifications of the
same invention. Indeed, if the law allowed the grant of two patents for a single invention, the
patentee could extent the patent term (in other words: the statutory period of monopoly) by
the amount of time that elapsed between the two dates of issuance. To prevent an “end run”
1 Student at Universiteit Antwerpen (Belgium) and Universidade Católica Portuguesa (Portugal).
1

around the stringent term limitations, both United States and European law allow a second
patent to issue only on a patentably distinct invention (this will be discussed more in depth in
part two: “standard of duplicity”).
It is important to stress that double patenting is concerned with attempts to “claim” related
subject matter twice; it does not preclude a second patent on subject matter which is disclosed
but not claimed in the first patent.
2.2 Historical development
It is noteworthy that United States nor European patent statutes have ever expressly codified
the doctrine of double patenting. 2 However, both legal systems have fully accepted the
doctrine via case law.
2.2.1 United States
When it comes to the United States, support for the double patenting doctrine has been
created by several decisions of the Supreme Court (of which the most significant one is
without any doubt the landmark case Miller v. Eagle Mfg. Co. 3 ).
It all started in 1866 with the Suffolk Mfg. v. Hayden case 4 in which Suffolk got sued by
Hayden for infringement of a patent on an improvement relating to cotton cleaners and thus in
fact, got accused of double patenting. The Court rejected this argument and hereby gave the
impression that the proposition was too obvious for discussion. Furthermore, the Court
indicated that a further improvement upon or new combination with a prior patented invention
2 It should be mentioned however that on the contrary, some national patent statutes have expressly codified the
doctrine of double patenting. For example, the patent law in the United Kingdom contains an express provision
relating to the prohibition of double patenting. The UK Patents Act 1977 (as amended) states in Section 18(5):
"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."
3 Miller v. Eagle Mfg. Co., 151 U.S. 186, 38 L. Ed. 121, 14 S. Ct. 310 (1894).
4 Suffolk Mfg. v. Hayden, 70 U.S. (3 Wall.) 315, 18 L. Ed. 76 (1866).
2

could support a new patent. Although double patenting got mentioned for the first time in a
United States Supreme Court case, it is more than obvious that this case is poles apart from
the modern double patenting doctrine.
Mosler Safe & Lock v. Mosler (1888) 5 involved two patents on improvements in fire-proof
safes. The first, issued 28 days before the second, was for the article, described as the product
of a certain mechanical process. The second was for the mechanical process. The Court
decided that the second patent could not validly been issued since “…the inventor cannot
afterwards, on an independent application, secure a patent for the method or process…to
produce the identical article covered by the previous patent.”
In the McCreary v. Pennsylvania Canal case (1891) 6 the Supreme Court stated in a similar
way (the case involved a patent upon an improved coupling and steering apparatus for
connected canal boats): “…if it be identical with it, or only a colorable variation from it, the
second patent would be void, as a patentee cannot take out two patents for the same
invention.” It is important to stress though that the Court’s statement is not a direct holding on
double patenting since it was said by way of obiter dictum (the validity of the patent was not
in issue since the defendant had not appealed). As we shall see further in this chapter, it is
only by the Miller v. Eagle Mfg. Co. case (1894) that the Supreme Court addresses the double
patenting issue in a clear way.
Underwood v. Gerber (1893) 7 involved an improved transfer surface for coating carbon
paper; interesting is that both patents were issued on the same day: one was for the
composition, and one for a sheet of material or fabric coated with the composition. Although
the Court’s real concern must have been with double patenting (make it the legal priority
5 Mosler Safe & Lock v. Mosler, 127 U.S. 354, 32 L. Ed. 182, 8 S. Ct. 1148 (1888).
6 McCreary v. Pennsylvania Canal, 141 U.S. 459, 35 L. Ed. 817, 12 S. Ct. 40 (1891).
7 Underwood v. Gerber, 149 U.S. 224, 37 L. Ed. 710, 13 S. Ct. 854 (1893).
3

number one) it seems to at least recognize this concern by referring to the previous case law
(as described above).
As mentioned above, the doctrine of double patenting has mainly been achieved by the
Supreme Court’s ruling on the Miller v. Eagle Mfg. Co. case (1894). 8 Without any doubt, it is
the leading Supreme Court case on double patenting since it is the only one with a full
discussion of the subject. In this case, which involved an improvement upon a wheeled
straddle-row cultivator, the Court stated the following paragraphs (which would become the
most frequently cited statement of the double patenting rule): “…no patent can issue for an
invention actually covered by a former patent, especially to the same patentee, although the
terms of the claims may differ; that the second patent, although containing a broader claim,
more generically in its character, than the specific claims, contained in the prior patent, is
also void; but that where the second patent covers matter described in the prior patent,
essentially distinct and separable from the invention covered thereby, and claims made there
under, its validity may be sustained. In the last class of cases it must distinctly appear that the
invention covered by the later patent was a separate invention, distinctly different and
independent from that covered by the first patent; in other words, it must be something
substantially different from that comprehended in the first patent. It must consist in something
more than a mere distinction of the breadth or scope of the claims of each patent. If the case
comes within the first or second of the above classes, the second patent is absolutely void.”
Since Miller v. Eagle Mfg. Co., US courts have repeatedly ruled that an inventor's separate
applications embodying the same inventive concept afford proper bases for the issuance of
separate patents at different times only if one of them also embodies an additional inventive
concept not present in the other. 9 In other words, the difference between the claims of the two
8 Miller v. Eagle Mfg. Co., 151 U.S. 186, 38 L. Ed. 121, 14 S. Ct. 310 (1894).
9 By way of example I refer to Pierce v. Allen B (1961) and Agrizap v. Woodstream Corp. (2008).
4

applications must itself be inventive. This will be discussed more in depth in the next chapter
(standard of duplicity).
2.2.2 Europe
Although the European Patent Convention (hereafter cited as EPC) does not contain any
specific provisions relating to double patenting, the EPO have however addressed the issue in
several cases. 10
Before we get to the EPO case law, it is important to point out the reason why the concept of
double patenting never got codified on the European level. In the preparatory documents of
the EPC 1973, the issue of double patenting was extensively discussed. Since double
patenting was regarded as an issue relating to patents, not to patent applications, and the EPC
did not relate to the maintenance of patents, it was left to the contracting states to permit or
prohibit simultaneous protection (Preliminary Works 1969, BR/7 e/69, p. 8 point 17). As a
consequence, the EPC does intentionally not (until today) contain a prohibition on double
patenting.
For many years, the EPO accepted that the double patenting doctrine can be found in the
European Patent Convention. However, the decision T 587/98 called this into question.
Although the official Guidelines for Examination at the EPO, more specifically C-IV, 6.4,
seem to be quite clear (“it is an accepted principle in most patent systems that two patents
shall not be granted to the same applicant for one invention”), the EPO considered in case T
587/98 whether there is any legal basis for the above practice. 11
10 In this paper, I especially focus on the recent EPO case law, more specifically: after the ratification of “EPC
2000”, the diplomatic conference held in Munich to revise the Convention on the grant of European patents of 5
October 1973, amongst other things to integrate in the European Patent Convention new developments in
international law, especially those of the TRIPS agreement and the Patent Law Treaty, and to add a level of
judicial review of the Boards of Appeal decisions. However, it should be stressed that European patent law
courts and agencies already discussed the double patenting issue before.
11 Decision of 12 May 2000, Case Number: T 587/98.
5

The T 587/98 case was all about a divisional application 12 of which the applicant argued that
the claims of the parent and divisional were not for “the same invention”. Besides he
considered a ban on double patenting had no basis in the EPC. The EPO held 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.” In other words: for a particular set of facts the EPO ruled that two patents with
overlapping claims could be granted in a parent application and an application divided there
from. However, the Board was careful not to reach any conclusions with wider applicability
to the case of double-patenting.
On the contrary, in June 2007, the Enlarged Board of Appeal of the EPO in cases G 1/05 and
1/06 13 accepted by way of obiter dictum that “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 therefore.”
Moreover, soon after in July 2007, the Technical Board in case T 307/03 14 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 Technical Board here fore found support on the
12
A divisional patent application is a type of patent application which contains matter from a previously filed
application (the so-called parent application).
13
Decision of 28 June 2007, Case Number G 1/05 of the Enlarged Board of Appeal of the EPO.
14
Decision of 3 July 2007, Case Number T 307/03 of the Technical Board of Appeal of the EPO.
6

wording of article 60 EPC 15 which states that "[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”. Besides, it is
noteworthy that the Board explicitly disagrees a few paragraphs later with the apparent
conclusion of the earlier decision T 587/98 that there would be no basis in the EPC
prohibiting conflicting claims.
3. THE STANDARD OF DUPLICITY
3.1 United States
3.1.1 Statutory double patenting / identity test
There are two types of double patenting. The first is termed “statutory double patenting” or
“identity standard” and is never permitted. As its name suggests, it is raised solely based on
statutory grounds and is governed by 35 U.S.C. 101 that states “whoever invents or discovers
any new and useful process, machine, manufacture, or composition of matter or any new and
useful improvement thereof, may obtain a patent 16 therefore, subject to the conditions and
requirements of this title.” Therefore, when a claimed subject matter of a patent application
exactly corresponds to a claimed subject matter of another granted patent or a patent
application then the claimed subject matter is rejected under 35 U.S.C. 101 on a statutory
basis. Referring to the case law discussed above, the identity test finds some support in
15 Some scholars however do not agree with the EPO’s opinion, stating that article 60 EPC relates to who has the
right to a patent, not to the constitution of the right.
16 Note the single article “a” in “a patent”, which provides a textual argument for the identity standard.
7

Suffolk Mfg. v. Hayden, McCreary v. Pennsylvania Canal and one interpretation of Miller v.
Eagle Mfg. 17
It was judge Hand, who wrote many influential opinions in the area of patent law, who shaped
the identity standard in the Traitel Marble case in 1927. 18 The patents in question were for a
pattern and guide strip for terrazzo flooring. Hand indicated or at least seemed to indicate that
a second patent need only be for a separate invention and need not show invention over the
first patent. When it comes to the disclosures of the first patent, as good as all scholars cannot
agree more. However, when judge Hand also indicates that the claims of the second need not
show invention over the claims of the first, the majority of the scholars make a mockery of his
opinion; indeed the requirement that the improvement must be patentably distinct from the
basic invention in order to support a separate patent cannot be eliminated. In other words, we
have come to the prevailing view today: the patentability test. 19
3.1.2 Non-statutory (obviousness) double patenting / patentability test
The other type of double patenting is termed “obviousness double patenting” or “non-
statutory double patenting”. In this case, the double patenting rejection is based on a
judicially created doctrine specifically proposed to avoid extension of patent term beyond 20
years. This rejection is raised to prevent grant of claims of a patent application that are not
patentably distinct from claims of a granted patent or a patent application cited by an
examiner. This standard equates double patenting with the nonobviousness or “invention”
requirement of patentability. Referring to the case law discussed above, the identity test finds
17
Suffolk Mfg. v. Hayden, 70 U.S. (3 Wall.) 315, 18 L. Ed. 76 (1866); McCreary v. Pennsylvania Canal, 141
U.S. 459, 35 L. Ed. 817, 12 S. Ct. 40 (1891); Miller v. Eagle Mfg. Co., 151 U.S. 186, 38 L. Ed. 121, 14 S. Ct.
310 (1894).
18
Traitel Marble Co. v. U.T. Hungerford Brass & Copper, 22 F.2d 259 (2d Cir. 1927).
19
As a consequence, the identity test seems to be the minority view.
8

some support in Mosler Safe & Lock v. Mosler, Underwood v. Gerber, and an alternative
interpretation of Miller v. Eagle Mfg. 20 Moreover, this standard is the prevailing view today.
It is important to stress that unlike the identity test, the patentability test constitutes a bar only
if the applicant fails to enter a terminal disclaimer which ties the two patents together as to
ownership and expiration date. This will be discussed more in depth in the next chapter.
When it comes to the patentability test, without any doubt the landmark case is Weatherhead
v. Drillmaster Supply Co. (1955). 21 In this case, the first patent disclosed and claimed a
certain metal packing ring for use as a joint for pipe connections; the second patent claimed
the same subject matter expect that it specified that the metal be “low carbon steel which has
been surface hardened by means of a potassium cyanide bath.” The Supreme Court clearly
held that the proper test was whether the claim of the later patent showed invention beyond
the claim of the first: “when determining whether or not double patenting exists only the
claims are compared, and the claim of the later patent must show an invention beyond the
claim of the first.”
3.2 Europe
As described above, there was a time that the EPO questioned the double patenting principle
being codified in EPC (case T 587/98). However, since the ruling on case T 307/03 the EPO
held that a principle of prohibition of double patenting was applicable under EPC, hereby
making a legal U-turn.”
3.2.1 Case T 1391/07 22
20 Mosler Safe & Lock v. Mosler, 127 U.S. 354, 32 L. Ed. 182, 8 S. Ct. 1148 (1888); Underwood v. Gerber, 149
U.S. 224, 37 L. Ed. 710, 13 S. Ct. 854 (1893); Miller v. Eagle Mfg. Co., 151 U.S. 186, 38 L. Ed. 121, 14 S. Ct.
310 (1894).
21 Weatherhead Co. v. Drillmaster Supply Co. (7 Cir. 1955), 227 F.2d 98, 102.
22 Decision of 7 November 2008, Case Number: T1391/07.
9

More recently, in November 2008, the EPO has made an all by all controversial ruling
concerning the double patenting doctrine. The Board held that a double patenting objection
did not arise when the claims of two applications only overlap. In other words, when there is a
partial overlap in the respective scopes of protection, there is at least one technical feature in
each of divisional claim 1 and parent claim 1 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 was found by the Board to be in line with previous decisions such as the obiter dictum in
decisions G 1/05 and G 1/06 as discussed above. 23 Some scholars however, were not too
convinced of the Board’s decision.
3.2.2 Case T 1423/07 24
Another remarkable recent case ruled by the EPO is case T 1423/07 in which the EPO
disagreed with the opinion of the Examining Division, according to which a second
application cannot be granted on the grounds that the claims on file were identical to the
claims granted in the first application from which priority was claimed.
Unlike the Examining Division, the EPO denied existence of an "accepted principle in most
patent systems" and disagreed the above-sketched EPO case law, since, firstly, the EPC does
not contain an explicit provision prohibiting double patenting and, secondly, since most
Contracting States have provisions prescribing that a national patent ceases to have effect in
case of double patenting with a European patent, which are, however, not related to double
patenting in the pre-granting stage. In fact, the Board did not find a principle of procedural
23 Decision of 28 June 2007, Case Number G 1/05 of the Enlarged Board of Appeal of the EPO.
24 Decision of 27 April 2010, Case Number: T 1423/07.
10

law generally accepted in the Contracting States that the refusal of an application for double
patenting is provided for.
As described above, the Board in case T 307/03 based its ruling that a patent cannot be
granted on a divisional application claiming the same subject-matter as the parent application
on article 60 EPC. On the contrary, in case T 1423/07, the EPO concluded that there is no way
that this article could provide a basis for refusing a European application under article 97(2)
EPC for double patenting. More concretely, the Board found that “the fact that the EPC does
not contain any specific provisions relating to double patenting is decisive: in the absence of
such provisions, a refusal of a European patent application for double patenting is not
possible irrespective of whether or not double patenting is a rare occurrence.”
Furthermore, the Board addresses the German law under which the earlier application from
which priority is claimed is deemed withdrawn with the declaration of priority. In this
situation double patenting cannot arise.
Finally, the Board argued that also the situation in G 1/05 was considered different to that of
the underlying appeal, since in G 1/05 the parent and its divisional application had the same
filing date, while in T 1423/07 the term of the patent to be granted on the second application
is to be calculated from its own filing date and not from the filing date of the priority
application. Thus, the applicant has a legitimate interest in obtaining longer protection based
on his second application.
The case T 1423/07 has lead to a major debate within the legal doctrine and even led some
scholars use bold slogans such as “double patenting is possible according to the EPC,” 25
which in my humble opinion is a little too far-reaching and far-fetched. Indeed, the EPC does
not suddenly allow double patenting but simply makes a distinction between what does fall
25 See http://www.visaepatentes.com/.../t-142307-double-patenting-is-possible.html.
11

under the double patenting principle and what does not, hereby providing reasonable
arguments.
4. THE TERMINAL DISCLAIMER PRINCIPLE IN US PATENT LAW
4.1 Definition
Nowadays, US patent law (US Patent Act § 253) allows any patentee or applicant “to disclaim
or dedicate to the public the entire term, or any terminal part of the term, of the patent
granted or to be granted”. 26 Basically, the idea is that a terminal disclaimer which causes a
second patent to the same inventor to expire on the same date as the first, will cure the double
patenting problem in all situations except where two patents are for identical subject matter.
The terminal disclaimer principle was adopted in a line of decisions of the Court of Customs
and Patent Appeals (hereafter cited as CCPA), which will be discussed below.
4.2 Historical development
Regarding the historical development of the terminal disclaimer principle, two CCPA cases
are noteworthy.
Firstly, the In re Siu case (1955) 27 which involved an application by Siu for a patent on a
method of making glass wool. Siu filed a disclaimer under section 253 of any part of his
patent as would extend beyond the expiration date of the first patent. The Board of Appeals of
the Patent Office declined to give effect to the disclaimer, noting that extension of the
monopoly was only one of the evils of double patenting. Although the solicitor of the Patent
office seemed to give somewhat more significance to terminal disclaimers than did the Board
of Appeals, the CCPA indicated that it agreed with the decision by the Board and affirmed
26
Please note that US patent law has long provided for the disclaimer of invalid claims. Only in the Patent Act of
1952, Congress provided in the disclaimer section (253) that in like manner a patentee or applicant can disclaim
all or a terminal part of the statutory term of monopoly.
27
222 F.2d 267, 105 U.S.P.Q. 428 (C.C.P.A. 1955).
12

without further and unnecessary comment. Thus, despite the fact that the holding of the Siu
decision is far from clear (it did not indicate precisely how much of the reasoning of the
Board of Appeals and the solicitor it was adopting), it clearly discouraged the use of terminal
disclaimers.
However, in the Robeson case (1964) 28 the court clearly distinguished and finally discarded
the implications of the Siu decision. Judge Worley noted that the terminal disclaimer obviated
the primary objection to double patenting: extension of the monopoly. He distinguished Siu
by arguing that the application in question did involve “an obvious variation” but more than a
“mere colorable variation.”
Cases after Robeson abandoned the concept of the “colorable variation” and recognized the
efficacy of the terminal disclaimer. Nowadays, the principle is fully adopted by both US case
law and legal doctrine.
5. CONCLUSION
In this paper I have provided an overview of the concept of double patenting in both US and
European patent law.
It is clear that the discussion on double patenting is far from over, on the contrary is very
much alive, especially when it comes to the European patent law (in this regard I refer to the
above discussed recent EPO case law). In my opinion, there are two main reasons here for.
First of all the fact that United States nor European patent statutes have ever expressly
codified the doctrine of double patenting. Indeed, the doctrine was only adopted by case law.
It is quite surprising that such a broadly supported principle has not been codified at the
28 331 F.2d 610, 141 U.S.P.Q. 485 (C.C.P.A. 1964).
13

international level. 29 It becomes even more bizarre given the specific legislation of national
patent laws such as UK patent law which contains an express provision relating to the
prohibition of double patenting (see UK Patents Act 1977, section 18(5)). Thus, codifying the
doctrine of double patenting on the international level could be a solution to provide more
legal certainty as well avoid any more discussion concerning the existence of the double
patenting principle.
Secondly, the absence of the terminal disclaimer principle in European patent law. As judge
Worley already indicated decades ago concerning US patent law, the terminal disclaimer
principle obviates the primary objection to double patenting: extension of the monopoly.
Thus, fully adopting this principle into European patent law (either by way of case law or
legislation) would withhold the EPO to rule such cumbersome and debatable case law.
29
Especially when it comes to Europe, the legislator clearly missed the opportunity of the EPC2000 to introduce
the prohibition in the law.
14

6. BIBLIOGRAPHY
6.1 US patent law
6.1.1 Books
D.S. CHISUM, Patents. A treatise on the Law of Patentability, Validity and Infringement,
Matthew Bender, 1987, 1393 pages.
S.P. LADAS, Patents, Trademarks, and Related Rights: National and International
Protection, Harvard University Press, 1990, 1888 pages.
J. DRATLER, Intellectual Property Law: Commercial, Creative and Industrial Property,
Lawcatalog, 1991, 2500 pages.
H.J.A. CHARMASSON and J. BUCHACA, Patents, Copyrights and Trademarks for
Dummies, Wiley Publishing, 2008, 384 pages.
7.1.2 Websites
http://www.uspto.gov/web/offices/pac/mpep/documents/0800_804.html
http://www.ipproinc.com/admin/uploads/Double_Patenting_74.pdf
7.2 European patent law
7.2.1 Books
I. MUIR, M. BRANDI-DHORN and S. GRUBER, European Patent Law: Law and
Procedure under the EPC and PCT, Oxford University Press, 2003, 448 pages.
M. SINGER and D. STAUDER, European Patent Convention: a commentary,
Thomson/Sweet & Maxwell, 2003, 653 pages.
7.2.2 Websites
15

www.epo.org/patents.html
www.wipo.int/about-ip/en/
www.visaepatentes.com/.../t-142307-double-patenting-is-possible.html
http://ipkitten.blogspot.com/2009/03/derk-visser-on-double-patenting.html
16