Evaluation of Claim Amendments

S. Adams (DE)

Many practitioners who attempt to steer patent applications through the gauntlet of prosecution are painfully aware of the different ways the applications are assessed on opposite sides of the Atlantic. The difference in assessment is perhaps most visible with regard to claim amendments. While starting from virtually the same roots and having more similarities than might be initially apparent, the EPO and the USPTO approach changes to claims in patent documents very differently. Although the EPO might be accused of being biased against applicants when assessing amendments, particularly in comparison to their American counterpart, the approach of the USPTO seems to defy clear explanation.

Applicable Law and Brief Interpretation

The applicable law for assessing the formal allowability[1] of amendments to the claims before the USPTO is the "written description" requirement of 35 U.S.C. 112(a). It reads, in relevant part, as follows:

“The specification[2] shall contain a written description of the invention”.

In more detail, to meet the written description requirement, the applicant must convey “with reasonable clarity to those skilled in the art that, as of the filing date sought, he or she was in possession of the invention… now claimed” (Vas-Cath v. Mahurkar, Fed. Cir. 1991). Further, an applicant shows "possession" by describing the claimed invention with all of its essential novel elements (Lockwood v. American Airlines, Fed. Cir. 1997).

Under 35 U.S.C. Sec. 112, the “specification” contains a written description and concludes with the claims. Drawings are covered by Sec. 113, a separate provision. However, in the context of the written description requirement, “possession may be shown … by showing that the invention was ‘ready for patenting’ such as by the disclosure of drawings” (MPEP, 2163.02).

Also, a US Examiner should be “mindful of the prohibition against the addition of new matter in the claims or description” (MPEP, 2163.04, I).

The applicable law for a corresponding assessment before the EPO is Article 123(2) of the European Patent Convention. It reads, in relevant part, as follows:

“The European patent application … may not be amended in such a way that it contains subject-matter which extends beyond the content of the application as filed”.

Thus, claim amendments “are permitted within the limits of what the skilled person would derive directly and unambiguously, using common general knowledge[,] from the application as filed” (CLBA, II.E.1).

Similarities in the Approaches of the EPO and the USPTO When Assessing Claim Amendments

1. The requirements of 35 U.S.C. 112(a) and Art. 123(2) EPC serve a similar goal

In particular, the written description requirement prevents claim amendments that introduce "new matter" into the disclosure of the invention. “The proscription against the introduction of new matter in a patent application … serves to prevent an applicant from adding information that goes beyond the subject matter originally filed” (MPEP, 2163, I, B).

Similarly, as articulated by the Enlarged Board of Appeal of the EPO, “the underlying idea [of Article 123(2) EPC] is clearly that an applicant shall not be allowed to improve his position by adding subject-matter not disclosed in the application as filed” (G 1/93, reasons 9).

2. A requirement to submit a basis for claim amendments is also provided for

According to USPTO regulations, “[a]ll claims being currently amended … shall be … submitted with markings to indicate the changes that have been made” (37 CFR 1.121 (c)(2); see also MPEP, 714, II.C).

Further, “Applicant should… specifically point out the support for any amendments made to the disclosure” (MPEP, 2163, II , A) and when “the support for the [claim] limitation is not apparent, and applicant has not pointed out where the limitation is supported”, a statement from the Examiner to this effect may be enough to support a rejection[3] for lack of adequate written description (MPEP, 2163.04, I).

The EPO has implemented this requirement more concisely in Rule 137(4) EPC:

“When filing any amendments … the applicant shall identify them and indicate the basis for them in the application as filed”.

3. Subject matter must be disclosed to be available as a claim amendment.

“To comply with the written description requirement of 35 U.S.C. Sec. 112(a) … each claim limitation must be expressly, implicitly, or inherently supported in the originally filed disclosure” (MPEP, 2163, II, 3, (b)). What is claimed by the patent application must be the same as what is disclosed in the specification; claims directed to a “distinct invention from that disclosed in the specification” do not satisfy the written description requirement (Lockwood v. American Airlines, Inc. (Fed. Cir. 1997)).

Similarly, the EPO requires the claims to be directly derivable from the originally filed application, also taking into account any features implicit to a person skilled in the art in what is expressly mentioned in the document (GL, H-III, 2.1-2.2).

4. Rendering a claim amendment obvious is not sufficient

Although amendments based on what is implied by the original application are allowed by both the EPO and the USPTO, amendments rendered obvious by the original disclosure are not.

Referring to the case law of the Federal Circuit, “ a description that merely renders the invention obvious does not satisfy the [written description] requirement” (Ariad v. Eli Lilly, Fed Cir., en banc, 2010). “Entitlement to a filing date does not extend to subject matter which is not disclosed, but would be obvious over what is expressly disclosed. It extends only to that which is disclosed” (Lockwood v. American Airlines, Fed. Cir. 1997).

Similarly, in T 118/88, a Technical Board of Appeal of the EPO concluded that “[o]bviousness is not… an allowable replacement for disclosure. … in the examination of what has been disclosed, novelty criteria may be applied, but not … obviousness”. (T 118/88, reasons 4.4). Accordingly, “the question of what may be rendered obvious by [the] disclosure [of a document] in the light of common general knowledge is not relevant to the assessment of what is implied by the disclosure of that document” (T 823/96, emphasis added).

5. Literal disclosure of claim amendments is not required

Just as a disclosure rendering a claim obvious is not sufficient, there also seems to be common ground that literal disclosure of new claim language is not required.

Referring to the MPEP, the “subject matter of the claim need not be described literally … in order for the disclosure to satisfy the [written] description requirement” (MPEP, 2163.02). In Kennecott Corp. v. Kyocera International, Inc. the Federal Circuit held that ''the earlier and later applications need not use the identical words, if the earlier application shows the subject matter that is claimed in the later application, with adequate direction as to how to obtain it ... an invention may be described in different ways and still be the same invention" (1987).

Similarly, the Guidelines for Examination in the EPO specify that literal support is “not required by the wording of Art. 123(2)” (GL, H-IV, 2.2).

6. A claim amendment may be supported by a drawing

In the following, the USPTO seems to put drawings on the same level as other means of description, “An applicant shows possession of the claimed invention by describing the claimed invention with all of its limitations using such descriptive means as words, structures, figures, diagrams, and formulas” (MPEP, 2163.02).

Similarly, according to the Technical Boards of Appeal, “[t]he drawings are not treated differently from either the claims or the description as regards amendments made to the application or to the patent itself as governed by Article 123” (T 169/83, reasons 3.2.5). Put another way, regarding the allowability of claim amendments, “[d]rawings were to be treated on an equal footing with the other parts of the application” (CLBA, II.E.1.5, emphasis in original).

Differences in the Approaches of the EPO and the USPTO When Assessing Claim Amendments

1. Burden of proof

The allocation of the burden of proof might be the most important difference between the approaches of the EPO and the USPTO. In particular, it seems likely that the allocation of the burden of proof is one of the main reasons that objections to claim amendments are far more common before the EPO than the USPTO.

Before the USPTO, "the examiner has the initial burden of presenting evidence or reasoning to explain why persons skilled in the art would not recognize in the original disclosure a description of the invention defined by the claims" (MPEP, 2163, II, A). Accordingly, once an indication of support in the application for claim amendments has been provided, a US Examiner bears the initial burden of making a case that the amendments cannot be derived from the original disclosure.

Before the EPO, the applicant has the initial burden of establishing that the requirements of Art. 123(2) EPC have been met after amending the claims, even assuming that the applicant has already cited portions of the application supporting the amendments. The indication of the basis for the amendments required by Rule 137(4) EPC "should be understood as an opportunity for the applicant to provide convincing arguments to the [examining] division as to why the amendment(s) is/are directly and unambiguously derivable from the application as filed" (GL, H-III, 2.1). Simply citing passages of the description having wording similar to the claim amendment in question is often insufficient. If a connection between the amended claims and the original application is not immediately clear to an EP Examiner, the Examiner can (and often does) simply object to the claims, without making a case to support the objection.

For example, in T 1239/03, a Technical Board of Appeal answered the question as to “which requirements have to be satisfied by the author of the amendment(s) in order to [establish] that the requirements of Article 123(2) EPC have been met”. Upon examination of claims amended by the patent proprietor, the Board found that the patent proprietor “has not discharged the burden of proof which was on him” in meeting the requirements of Art. 123(2) EPC. Accordingly, the amendments were not allowed.

2. Standard for evaluating claim amendments

An applicant before the USPTO generally has much more freedom to depart from the literal wording of the description than his counterpart before the EPO.

When an applicant amends a claim before the USPTO, the support for the claim amendment in the original disclosure need not exclude all possibilities other than the claim amendment. In other words, the claim amendment does not need to be unambiguously derivable from the original disclosure.

For example, in Vas-Cath v. Mahurkar, a US District Court interpreted the written description requirement in a way that is not so different from a typical interpretation of Art. 123(2) EPC. The Court found that the drawings provided in a priority application did not provide an adequate written description of claim 1 of a patent relying on the drawings for a filing date.

Claim 1 of one of US 4,568,329 (Mahurkar) specifies a double lumen catheter in which the diameter of the return lumen is greater than one-half but less than the full diameter of the catheter tubing. The Court posed the following question: "how does [the priority application] necessarily exclude" other ratios? The Court also noted that "Mahurkar's patents… contain limitations that did not follow ineluctably from the [priority application]". The phrases "necessarily exclude" and "ineluctably" suggest that the Court was of the opinion that the claimed ratio and other claimed limitations must be unambiguously derivable from the original disclosure.

The Federal Circuit held that the district court “erred in applying a legal standard that essentially required the drawings of the [priority] application to necessarily exclude all diameters other than those within the claimed range… the proper test is whether the drawings conveyed with reasonable clarity to those of ordinary skill that Mahurkar had in fact invented the catheter recited in those claims” (Vas-Cath Inc. v. Mahurkar, Fed. Cir., 1991).

Accordingly, the Federal Circuit held invalid a legal standard in which the original disclosure must "necessarily exclude" all other possibilities and "ineluctably" lead to the amended claims in favor of a lower standard of "reasonable clarity".

In Lizardtech Inc. v. Earth Resource Mapping Inc. (2005), the Federal Circuit found that “a recitation of how to make and use the invention across the full breadth of the claim is ordinarily sufficient to demonstrate that the inventor possesses the full scope of the invention, and vice versa”. In other words, if the claims are enabled (i.e. sufficiently disclosed), then the claims ordinarily meet the written description requirement (i.e. the claim amendments are formally allowable).

As discussed above, both the EPO and the USPTO require claim amendments to be directly derivable from the original application. Unlike the USPTO, the EPO also requires the claim amendments to be unambiguously derivable (GL, H-IV, 2.1). In other words, starting from the original application, formal allowability under Art. 123(2) EPC requires that the skilled person would inevitably (or ineluctably) arrive at the amended claim.

For example, in T 824/06 the claim at issue was directed to the preservation of a slaughtered chicken. The claim was amended during opposition proceedings to associate a maximum temperature of 15°C for the surface of the chicken with both a first cooling step and a second cooling step. The application discloses that the temperature of the surface of the chicken "is brought to a maximum of 15°C". However, the Board found that this indication "can be understood as being the result of the overall process and not as a requirement for each individual cooling step".

The Board accepted the appellant's argument that providing for a maximum temperature of 15°C for the cooling steps would be a reasonable way to carry out the invention. The Board also indicated that the amendment would be "within the scope of the disclosure of the application as originally filed" and would meet a standard of "reasonable plausibility". Presumably, reasonable plausibility is similar to the standard of reasonable clarity articulated by the Federal Circuit. However, the Board rejected the amendment in view of the stricter requirement of "unambiguous disclosure", particularly because the application did not unambiguously disclose that the maximum temperature of 15°C was applicable to the claimed cooling steps.

3. Claim amendments derived via (intermediate) generalization

In contrast to EP practice, the US practice with regard to generalizations seems to be rather liberal. In particular, it appears that a preferred embodiment or a list of ranges can often be used to derive generic claim language, at least in the absence of inconsistencies or specific disclosure to the contrary.

For example, “where no explicit description of a generic invention is to be found in the specification ... mention of representative compounds may provide an implicit description upon which to base generic claim language” The disclosure of forty working examples was found to sufficiently describe the subject matter of claims directed to a generic process (In re Robins, 57 CCPA 1321, 1970).

In the case of In re Smith, the specification disclosed two methods of making polymers. The second method included starting materials “free of alkylatable groupings”, while the first method did not specify this particular limitation. The USPTO Board of Appeals held that the disclosure of the specification was not sufficient to support a broad claim for all polycationically active polymers free of alkylatable groups. A Technical Board of Appeal at the EPO might have agreed with the USPTO Board of Appeals.

The CCPA heard the appeal of the decision of the USPTO Board of Appeals in In re Smith, and did not agree. According to the CCPA, the specification did not contain ''language which corresponds identically to the language of the claims on appeal,'' but the ''tenor of the specification” was that the applicant had made a generic invention, not one limited only to certain particular polycationically active polymers (In re Smith, 481 F.2d 910, 1973).

From the opinion in Union Oil Co. of California v. Atlantic Richfield Co. (Fed. Cir., 2000), the “Appellant refiners assert that the specification does not describe the exact chemical component of each combination that falls within the range claims of the '393 patent. However, neither the Patent Act nor the case law of this court requires such detailed disclosure”, and citing an earlier decision, “ranges found in applicant's claims need not correspond exactly to those disclosed in [the specification]; [the] issue is whether one skilled in the art could derive the claimed ranges from the [ ] disclosure.” (Vas-Cath Inc. v. Mahurkar, Fed.Cir., 1991)

However, US judges occasionally offer stricter opinions. In his dissent in Union Oil Co. of California v. Atlantic Richfield Co. (2000), Judge Lourie argued that the specification is required to give “full, clear, concise, and exact direction” to a claimed combination of limitations in order to meet the written description requirement. Judge Lourie did not favor the “picking and choosing” from the specification that was required to arrive at the limitations of the claims at issue.

Also, the Federal Circuit invalidated claims broader than the disclosed embodiments because "[t]here is no evidence that the specification contemplates a more generic way" of performing the claimed invention (LizardTech Inc v. Earth Resource Mapping Inc., Fed. Cir. 2005).

Similarly, the Federal Circuit recently affirmed an examiner, who, in arguing that the written description requirement was not met, held that "while each element [of the claim] may be individually described in the specification, the deficiency was lack of adequate description of their combination" (Hyatt v. Dudas, Fed. Cir. 2007).

Claim amendments derived by generalizing features from the description are generally not allowed under EP practice. In particular, an amendment is not allowable under Art. 123(2) EPC when it replaces “a disclosed specific feature either by its function or by a more general term and thus incorporate[s] undisclosed equivalents into the content of the application as filed” (CLBA, II.E.1.2).

Judge Lourie’s description of “picking and choosing” features to arrive at the limitations of a claim appears to correspond to what the EPO refers to as an “intermediate generalization”. According to EPO practice, an intermediate generalization occurs when a claim is limited “by a feature extracted from a combination of features” (GL, H-V, 3.2.1).

In general, the EPO allows an intermediate generalization “only in the absence of any clearly recognisable functional or structural relationship among the features of the specific combination” (CLBA, II.E.1.2). This means that if a claim is to be restricted to a preferred embodiment, it is normally not permissible “to extract isolated features from a set of features which had originally been disclosed in combination for that embodiment” (Id.).

4. Different Goals of the Written Description Requirement and Art. 123(2) EPC

Article I, Section 8, Clause 8, of the US Constitution grants Congress the power "[t]o promote the progress of science and useful arts, by securing for limited times to authors and inventors the exclusive right to their respective writings and discoveries". This clause is the reason the US Congress is able to enact patent legislation. In order to comply with the cited clause of the US Constitution, the written description requirement should serve the goal of promoting the progress of science and useful arts.

Accordingly, "the written description requirement promotes the progress of the useful arts by ensuring that patentees adequately describe their inventions in their patent specifications in exchange for the right to exclude others from practicing the invention for the duration of the patent’s term" (MPEP, 2163, I). The term "adequate" is used in the context of the written description requirement at various other points in the MPEP (e.g. MPEP, 2103, IV, B), as well as in a number of decisions of the Federal Circuit (e.g. Vas-Cath Inc. v. Mahurkar, Fed. Cir., 1991).

In contrast, the Enlarged Board of Appeal held that adding undisclosed subject matter to an application "could be damaging to the legal security of third parties relying on the content of the original application" (G 1/93). Although legal security is not mentioned in the EPC, the Protocol on the Interpretation of Art. 69 EPC, for determining the extent of protection of a European patent or application, specifies that Art. 69 EPC "is to be interpreted as defining a position… with a reasonable degree of legal certainty for third parties".


The US approach to claim amendments can be characterized as more lenient than the "strict" approach of the EPO. Policy justifications have been brought forward for both approaches.

In an early decision discussing the assessment of claim amendments, a Technical Board of Appeal opined that under a lenient approach "there is a definite risk that the protection conferred by the patent would actually be extended if, as a result of amendments to clarify the granted claims, the claims may be more widely construed than a court would have construed them by the application of Article 69 EPC" (T 113/86, reasons 2.2).

In an even earlier decision of the CCPA, the Court held that a strict approach "places upon patent applicants, the Patent Office, and the public the undue burden of listing, in the case of applicants, reading and examining, in the case of the Patent Office, and printing and storing, in the case of the public, descriptions of the very many structural or functional equivalents of disclosed elements or steps which are already stored in the minds of those skilled in the arts, ready for instant recall upon reading the descriptions of specific elements or steps" (In re Smythe, 1973).

While the strict approach is sometimes less than ideal for patentees, it is questionable whether the lenient approach can be consistently applied. After listing various efforts of US courts to articulate the standard for adequate written description in his treatise on US patent law, Professor Donald Chisum wryly notes that "[i]t can seriously be questioned whether any of these articulations provide a standard clearer or more certain than the statutory language itself, which is, in simple terms, whether the specification describes to a person of ordinary skill in the art the invention later claimed" (Chisum on Patents, § 7.04[1][e], 2007).

Abbreviations used in this article
CCPA - United States Court of Customs and Patent Appeals (predecessor of the Federal Circuit)
CLBA – Case Law of the Boards of Appeal of the European Patent Office, Seventh Edition, 2013
CFR – Code of Federal Regulations (US)
EP - European
EPC – European Patent Convention
EPO – European Patent Office
Fed. Cir./Federal Circuit - United States Court of Appeals for the Federal Circuit
GL – Guidelines for Examination in the European Patent Office, 2015
MPEP - Manual of Patent Examining Procedure for the United States Patent and Trademark Office, Ninth Edition, November 2015 revision
USC – United States Code

  1. In examination proceedings before the EPO, "allowability" refers to the application of Art. 123(2) EPC, whereas "admissibility" refers to procedural requirements that must be met before compliance with Art 123(2) EPC is assessed. The term "formal allowability" occasionally appears in opinions of the Boards of Appeal of the EPO and is used in this article with respect to the assessment of claims before both the EPO and the USPTO.
  2. The EPC and EPO Examination Guidelines use the term “specification” differently than the US Patent Act. In the EPC (e.g. Art. 98, 103), the term “specification” refers to an entire published patent, including drawings, and is not used in the context of an application. In contrast, the US Patent Act (e.g. 35 U.S.C. Sec. 10-12) uses “specification” in the context of both applications and patents to refer to the description and claims while excluding the drawings.
  3. According to MPEP, 706.01, a "rejection" relates to the substance of a claim, whereas an "objection" is raised with respect to formal aspects of a claim.