Claim Scope and Disclosure in U.S. and Chinese Patent Law: Written Description, Support, Sufficient Disclosure, and the Forum-Specific Nature of Review

Introduction

The easiest comparative mistake is to say that U.S. “written description” and Chinese “support by the description” are the same doctrine under different names. They are not. They respond to a similar overclaiming problem, but they operate through different statutory provisions, different institutional settings, and different vocabularies.

In the United States, the central doctrine is the written-description requirement of 35 U.S.C. § 112(a). It asks whether the specification shows that the inventor possessed the claimed invention as of the filing date. Ariad Pharms., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1351 (Fed. Cir. 2010) (en banc). In China, there is no exact doctrinal counterpart to U.S. written description. The closer comparison is a cluster of rules: Article 26(3), requiring sufficient disclosure; Article 26(4), requiring claims to be based on the description; and Article 33, barring amendments beyond the original disclosure. Patent Law of the People’s Republic of China arts. 26(3)–(4), 33 (promulgated Mar. 12, 1984, amended Oct. 17, 2020) (China). CNIPA’s English translation states that the description must clearly and comprehensively describe the invention so that a skilled person can carry it out, that the claims must be based on the description, and that amendments to invention and utility-model applications may not go beyond the original description and claims.

This article’s comparative point is narrower than a general survey: Article 26(4) support is the closest Chinese analogue to U.S. written description, but it is not a possession doctrine. In Chinese materials, the inquiry is framed around whether the claimed technical solution can be obtained or reasonably generalized from the sufficiently disclosed contents of the description and drawings. That difference is not cosmetic. It changes how a lawyer should draft specifications, argue invalidity, defend amendments, and present foreign-law comparisons.

Part I explains the U.S. distinction between written description and enablement, including the post-Amgen v. Sanofi enablement overlay for broad genus claims. Part II defines the Chinese concept of “technical solution” and separates CNIPA examination, CNIPA invalidation, and judicial review. Parts III through VI compare Article 26(4) support, Article 26(3) sufficient disclosure, biological genus claims, and Article 33 added matter. Part VII identifies drafting and litigation implications.

I.             U.S. Law: Written Description as Possession, Enablement as Full-Scope Teaching

The modern U.S. written-description doctrine is anchored in Ariad. The Federal Circuit held en banc that § 112(a) contains a written-description requirement separate from enablement. Ariad, 598 F.3d at 1344–45. The operative test is whether the specification “reasonably conveys to those skilled in the art that the inventor had possession of the claimed subject matter as of the filing date.” Id. at 1351. The inquiry is objective, made from the perspective of a person of ordinary skill in the art, and focused on the four corners of the specification. Id.

That possession test grew out of earlier priority and new-matter cases. Vas-Cath Inc. v. Mahurkar framed the issue as whether the disclosure reasonably conveys possession of the later-claimed subject matter and held that drawings can provide written-description support when they convey the claimed invention with sufficient clarity. 935 F.2d 1555, 1563–66 (Fed. Cir. 1991). In re Ruschig supplied the classic “blaze marks” principle: a broad disclosure of possible chemical choices does not necessarily describe a later-claimed species unless the specification directs the skilled artisan to that species. 379 F.2d 990, 994–96 (C.C.P.A. 1967). Lockwood v. American Airlines, Inc. sharpened the point for priority chains: an earlier application must itself describe the claimed invention with all limitations; it is not enough that the later claim would have been obvious from the earlier disclosure. 107 F.3d 1565, 1571–72 (Fed. Cir. 1997).

The overbreadth cases show the doctrine’s bite outside the chemical context. In Tronzo v. Biomet, Inc., the parent application disclosed conical acetabular cups, but later claims attempted to cover cup shapes generically; the Federal Circuit denied the broader claims the parent’s filing date. 156 F.3d 1154, 1159–60 (Fed. Cir. 1998). In Gentry Gallery, Inc. v. Berkline Corp., the patent described the recliner controls’ console location as central to the invention, yet later claims tried to omit that limitation; the Federal Circuit held the broader claims lacked written-description support. 134 F.3d 1473, 1479–80 (Fed. Cir. 1998).

Biotechnology and chemistry cases are more demanding because they often involve unpredictable structure-function relationships. In Regents of the University of California v. Eli Lilly & Co., disclosure of rat insulin cDNA did not support claims to vertebrate, mammalian, or human insulin cDNA because the specification did not adequately describe the broader genus. 119 F.3d 1559, 1566–69 (Fed. Cir. 1997). In Fiers v. Revel, a DNA molecule claimed by biological function was not adequately described by a method for obtaining it; the disclosure looked more like a research plan than a description of the claimed DNA. 984 F.2d 1164, 1170–71 (Fed. Cir. 1993). In University of Rochester v. G.D. Searle & Co., claims to methods of selectively inhibiting COX-2 failed because the patent disclosed screening assays but no compounds capable of performing the claimed method. 358 F.3d 916, 927–28 (Fed. Cir. 2004). In Boston Scientific Corp. v. Johnson & Johnson, claims to rapamycin analogs on drug-eluting stents lacked written description where the specification disclosed rapamycin but no representative analog structures, formulas, or species. 647 F.3d 1353, 1365–67 (Fed. Cir. 2011).

Functional language is not forbidden. Enzo Biochem, Inc. v. Gen-Probe Inc. recognized that functional characteristics can contribute to written description when coupled with a known or disclosed correlation between function and structure, and that biological deposits can, in appropriate circumstances, describe deposited material. 323 F.3d 956, 964–68 (Fed. Cir. 2002). The written-description defect is narrower: the patentee cannot claim a functionally defined genus while disclosing only a desired result, a research plan, or an insufficient set of species.

Enablement must be kept separate. The Supreme Court’s 2023 decision in Amgen Inc. v. Sanofi was not a written-description case, but it is now unavoidable in any analysis of broad genus claims. 598 U.S. 594 (2023). The Court held that when a patent claims an entire class, the specification must enable the skilled artisan to make and use the full scope of that class; “the more one claims, the more one must enable.” Id. at 610–11. The Court rejected Amgen’s “roadmap” and “conservative substitution” disclosures because they amounted to research assignments rather than full-scope enablement. Id. at 612–14. Thus, for U.S. genus claims, Ariad asks whether the inventor described possession of the claimed genus, while Amgen asks whether the specification enables the full claimed scope without undue experimentation.

II.          Chinese Law: “Technical Solution” and the Three Institutional Settings

Chinese patent discourse is organized around “technical solution” (技术方案), “technical problem” (技术问题), and “technical effect” or “beneficial effect” (技术效果 / 有益效果). Article 2 of the Patent Law defines an invention as a “new technical solution” proposed for a product, process, or improvement, and a utility model as a new technical solution for product shape, structure, or their combination. Patent Law art. 2 (China). CNIPA’s Patent Examination Guidelines instruct that the specification should state the technical problem, the technical solution used to solve it, and the beneficial effects, and that these elements should be mutually adapted rather than contradictory or unrelated. CNIPA, Patent Examination Guidelines pt. II, ch. 2, § 2.1.1 (2023) (China).

For a U.S. audience, “technical solution” should not be understood as merely the words of the claim. It refers to the set of technical means adopted to solve a technical problem and achieve a technical effect. That vocabulary shapes both support and sufficiency analysis. In a Chinese support dispute, the question is often not simply whether claim words appear somewhere in the application; it is whether the claimed technical solution is justified by the disclosed technical teaching.

The institutional setting matters. The same statutory words can appear in three different postures: CNIPA examination, CNIPA invalidation, and judicial review of CNIPA decisions.

A. CNIPA Examination

During prosecution, CNIPA examines whether the application complies with the Patent Law, Implementing Regulations, and the Patent Examination Guidelines. The Patent Law provides that, after substantive examination, if CNIPA finds that an invention application does not conform to the law, it shall notify the applicant and require observations or amendment; if the application still does not conform, it shall be rejected. Patent Law arts. 37–38 (China).

In this setting, Article 26(4) support operates as an examination standard. CNIPA’s Guidelines state that “claims shall be based on the description” means that the claims must be supported by the description, and that each claimed technical solution must be obtainable or generalizable by the skilled person from the fully disclosed contents of the description and must not exceed the scope disclosed. CNIPA, Patent Examination Guidelines pt. II, ch. 2, § 3.2.1 (2023) (China). The Guidelines further provide that if a broad generic or Markush-style generalization contains speculative subject matter whose effect is difficult to predict or evaluate, the generalization may exceed the disclosed scope; if the skilled person has sufficient reason to doubt that one or more lower-level concepts or alternatives solve the technical problem and achieve the same effect, the claim is unsupported. Id. 

This is also where the source of the “sufficient reason to doubt” phrasing should be cited precisely. CNIPA’s Jan. 18, 2024 explanation of the 2023 Guidelines amendments states that, in Part II, Chapter 2, § 3.2.1, three instances of “reason to doubt” were changed to “sufficient reason to doubt,” and that the plant-seed example was revised to add reasoning based on differences in low-temperature tolerance among different plant seeds. CNIPA, Explanation of the 2023 Amendments to the Patent Examination Guidelines (III) (Jan. 18, 2024) (China). CNIPA described the revision as emphasizing adequate reasoning when examiners conclude that a claim lacks support, and as avoiding conclusory assertions unsupported by analysis. Id. 

B. CNIPA Invalidation

After grant, the setting changes. Article 45 allows any entity or individual to request invalidation of a granted patent, and Article 46 requires CNIPA to examine the request, issue a decision, and notify the requester and patentee; a dissatisfied party may then file suit in a people’s court. Patent Law arts. 45–46 (China).

In invalidation, Article 26(3), Article 26(4), and Article 33 become grounds for attacking or maintaining a granted patent. Amendment practice is also more constrained than ordinary prosecution amendment. CNIPA’s Guidelines state that, in invalidation, amendments to invention or utility-model patent documents are limited to the claims; they must respond to invalidity reasons or defects identified by the panel; they must not change the subject name of the original claim, broaden the granted scope, exceed the original description and claims, or generally add technical features not included in the granted claims. CNIPA, Patent Examination Guidelines pt. IV, ch. 3, § 4.6.1 (2023) (China). The same section states that permissible amendment modes are generally limited to deletion of claims, deletion of technical solutions, further limitation of claims, and correction of obvious errors. Id. § 4.6.2.

This means that a Chinese invalidation strategy cannot be reduced to the abstract question “does the claim have support?” The patentee’s ability to repair a support or sufficiency problem may depend on the invalidation amendment rules. A narrowing amendment that might have been possible during prosecution may be unavailable or procedurally constrained after grant.

C. Judicial Review of CNIPA Decisions

Judicial review is a third posture, not simply another round of examination. The Supreme People’s Court’s patent grant-and-confirmation provisions define patent grant administrative cases as suits challenging CNIPA reexamination decisions and patent confirmation administrative cases as suits challenging CNIPA invalidation decisions. Provisions of the Supreme People’s Court on Several Issues Concerning the Application of Law in the Trial of Administrative Cases Involving Patent Grant and Confirmation (I), Fa Shi [2020] No. 8, art. 1 (promulgated Sept. 10, 2020, effective Sept. 12, 2020) (China) [hereinafter SPC Patent Grant & Confirmation Provisions].

For Article 26(3), SPC Article 6 frames the sufficient-disclosure inquiry as whether insufficient disclosure of particular technical content causes one of three filing-date defects: the claimed technical solution cannot be implemented; implementing it cannot solve the technical problem; or confirming that it solves the technical problem requires undue labor. SPC Patent Grant & Confirmation Provisions art. 6. Article 6 also states that a party cannot rely only on insufficiently disclosed technical content to argue that related claims are supported by the description under Article 26(4). Id. 

For Article 26(4), SPC Article 8 provides the closest judicial-review analogue to U.S. written description: if the skilled person, after reading the description and drawings, cannot obtain or reasonably generalize the claimed technical solution as of the filing date, the court should find the claim unsupported. SPC Patent Grant & Confirmation Provisions art. 8. Article 9 separately addresses functional or effect-defined technical features; if the claims, description, and drawings disclose no specific embodiment capable of achieving the function or effect, the court should find the description and the claims containing that feature noncompliant with Article 26(3). Id. art. 9.

The evidentiary posture also differs in court. SPC Article 10 provides that, in pharmaceutical patent grant-and-confirmation cases, courts shall examine supplementary experimental data submitted after the filing date when the applicant relies on that data to prove compliance with inventiveness or sufficient-disclosure requirements. Id. art. 10. Articles 29 and 30 distinguish new evidence submitted by patent applicants or patentees from new evidence submitted by invalidation requesters: applicants and patentees may generally submit new evidence to show an application should not be rejected or a patent maintained, while invalidation requesters’ new evidence in confirmation litigation is generally not examined except for listed categories. Id. arts. 29–30.

III.      Article 26(4) Support Compared with U.S. Written Description

Article 26(4) support is the closest Chinese analogue to U.S. written description because both doctrines prevent claims from outrunning the disclosure. But they do not use the same conceptual test.

U.S. written description asks whether the specification shows possession of the claimed invention. Ariad, 598 F.3d at 1351. The concern is disclosure of the invention as claimed: representative species, common structural features, identifying characteristics, or other disclosure sufficient to show that the inventor actually invented the claimed scope. Id. at 1350–52.

Chinese support doctrine, by contrast, is framed in terms of whether the claimed technical solution can be obtained or reasonably generalized from the specification. CNIPA’s examination guidance says each claimed technical solution must be obtainable or generalizable from the fully disclosed contents and must not exceed the disclosed scope. CNIPA, Patent Examination Guidelines pt. II, ch. 2, § 3.2.1 (2023) (China). The SPC judicial-review formulation says that if the skilled person cannot obtain or reasonably generalize the claimed technical solution after reading the description and drawings, the claim is unsupported. SPC Patent Grant & Confirmation Provisions art. 8.

The difference matters in advocacy. A U.S. brief may properly say that the patentee lacked possession of the full genus. A Chinese brief should generally avoid translating that assertion mechanically. The better argument is that the claim’s technical solution cannot be obtained or reasonably generalized from the disclosed technical content, or that the generalization includes alternatives that the skilled person has sufficient reason to doubt will solve the technical problem and achieve the same effect.

IV.       Article 26(3) Sufficient Disclosure Compared with U.S. Enablement

Article 26(3) is closer to U.S. enablement than to U.S. written description, though again the fit is imperfect. U.S. enablement asks whether the specification teaches the skilled artisan to make and use the claimed invention without undue experimentation. In re Wands, 858 F.2d 731, 736–37 (Fed. Cir. 1988). After Amgen, broad genus claims must be enabled across the full claimed scope, with reasonableness of experimentation depending on the nature of the art. Amgen, 598 U.S. at 610–14.

Chinese judicial materials frame sufficient disclosure through implementation, problem-solving, and technical effect. SPC Article 6 identifies lack of sufficient disclosure where the insufficiently disclosed content means the claimed technical solution cannot be implemented, cannot solve the technical problem, or requires undue labor to confirm that it solves the problem. SPC Patent Grant & Confirmation Provisions art. 6.

The SPC’s Warner-Lambert atorvastatin-crystal judgment illustrates the role of technical problem and implementability. The SPC stated that, under Article 26(3), the object of clear and complete disclosure is the invention or utility model, and that the analysis should first determine what the invention is and then whether the skilled person can implement the technical solution, solve the technical problem, and produce the expected technical effect. Patent Reexamination Bd. v. Warner-Lambert Co., (2014) Xing Ti Zi No. 8 (Sup. People’s Ct. 2014) (China). The judgment also records the invalidation decision’s chemical-crystal analysis: for a chemical crystal, the disclosure should identify composition and crystal structure, provide physicochemical parameters such as qualitative or quantitative data and spectra to prove composition and microstructure, and disclose at least one preparation method enabling implementation. Id. 

The lesson for comparative drafting is straightforward. U.S. written description focuses on whether the patentee described possession of the invention. Chinese Article 26(3) asks whether the description enables the skilled person to implement the technical solution, solve the technical problem, and achieve the expected technical effect. The doctrines may attack the same weakness in a patent, but the statutory hooks and evidentiary emphasis differ.

V.          Biological Genus Claims and the Novozymes Caveat

Biological genus claims expose the practical difference between U.S. possession and Chinese reasonable generalization.

In the United States, broad functional genus claims are vulnerable under both written description and enablement. For written description, Ariad and Eli Lilly require disclosure of representative species, common structural features, or other identifying characteristics sufficient to show possession of the genus. Ariad, 598 F.3d at 1350; Eli Lilly, 119 F.3d at 1568–69. For enablement, Amgen requires the specification to teach the skilled person to make and use the full scope of the claimed class, not merely to conduct a screening program. Amgen, 598 U.S. at 610–14.

The Chinese Novozymes thermostable glucoamylase case is useful but easy to overread. In Patent Reexamination Board & Novozymes A/S v. Jiangsu Boli Bioproducts Co., the SPC case summary states that the claims recited an isolated enzyme with glucoamylase activity, at least 99% homology with the full-length sequence shown in SEQ ID NO:7, an isoelectric-point limitation, and source limitations to Talaromyces emersonii species or the strain T. emersonii CBS 793.97. (2016) Zui Gao Fa Xing Zai No. 85 (Sup. People’s Ct. 2016) (China). The summary states that the combination of 99% homology and source or strain limitations narrowed the claims to an extremely limited group of enzymes, and that the claims also included isoelectric-point and glucoamylase-activity limitations. Id. 

That case should not be cited as a general endorsement of homology claiming. Its support holding depended on multiple narrowing features: high sequence homology, biological source, in some claims a specific strain, enzymatic activity, and isoelectric point. The SPC summary itself describes the case as clarifying judgment rules for biological sequence claims using homology plus source and function limitations. Id. A claim defined only by a high identity percentage, without source or function limits and without disclosure making the claimed breadth predictable, could still fail Article 26(4) support or Article 26(3) sufficiency.

VI.       Article 33 Added Matter Compared with U.S. Priority and New-Matter Cases

Article 33 should be kept separate from Article 26(4). Article 33 concerns amendments; it provides that amendments to invention or utility-model applications may not go beyond the scope of disclosure contained in the original description and claims. Patent Law art. 33 (China). Article 26(4), by contrast, concerns whether claims are based on the description. Patent Law art. 26(4) (China).

U.S. written-description doctrine often handles comparable issues through § 112(a) and priority under § 120. Lockwood states that priority extends only to what the earlier application discloses, not to subject matter that would have been obvious from that disclosure. 107 F.3d at 1571–72. Tronzo applies that principle where a parent disclosed only conical cups but later claims reached cup shapes generically. 156 F.3d at 1159–60.

In China, amendment analysis may appear during prosecution, invalidation, or judicial review, but the procedural rules differ. During prosecution, Article 33 constrains amendment to the original disclosure. During invalidation, CNIPA’s Guidelines further restrict patent-file amendments to claim amendments that do not broaden the granted scope, do not exceed the original description and claims, and generally do not add features not included in the granted claims. CNIPA, Patent Examination Guidelines pt. IV, ch. 3, § 4.6.1 (2023) (China). That institutional difference is a major reason not to collapse Chinese Article 33 into U.S. written description.

VII.   Practical Implications

For U.S. drafting, the lesson is to treat written description and enablement as separate gates. A specification should disclose representative species, structural features, sequence information, deposits, assays tied to structure, and technical rationale sufficient to show possession of the claimed scope. For broad genus claims, the same disclosure must also enable the full scope after Amgen. A roadmap that merely tells the skilled person to find working embodiments may fail enablement even if some species are disclosed. Amgen, 598 U.S. at 612–14.

For Chinese drafting, the specification should make the technical problem, technical solution, and technical effect explicit and mutually consistent. CNIPA’s Guidelines require the specification to state the technical problem, the technical solution used to solve it, and the beneficial effects, and to avoid inconsistency among those elements. CNIPA, Patent Examination Guidelines pt. II, ch. 2, § 2.1.1 (2023) (China). The claims should then be drafted at a level of generality that the skilled person can obtain or reasonably generalize from the fully disclosed content. CNIPA, Patent Examination Guidelines pt. II, ch. 2, § 3.2.1 (2023) (China); SPC Patent Grant & Confirmation Provisions art. 8.

For Chinese invalidation and judicial review, counsel should identify the procedural posture before selecting the doctrinal frame. In CNIPA invalidation, amendment constraints may determine whether a support or sufficiency defect can be cured. CNIPA, Patent Examination Guidelines pt. IV, ch. 3, § 4.6.1 (2023) (China). In judicial review, the court is reviewing CNIPA’s reexamination or invalidation decision, and SPC Articles 6, 8, 9, 10, 29, and 30 provide specific judicial rules for sufficient disclosure, support, functional features, supplementary pharmaceutical data, and new evidence. SPC Patent Grant & Confirmation Provisions arts. 6, 8–10, 29–30.

VIII.                  Conclusion

The U.S. and Chinese systems share an anti-overclaiming instinct, but they do not share a single disclosure doctrine. U.S. written description is a possession doctrine under § 112(a), operating alongside enablement after Amgen. Chinese law distributes comparable concerns across Article 26(4) support, Article 26(3) sufficient disclosure, and Article 33 added matter. The rule also behaves differently depending on whether the case is in CNIPA examination, CNIPA invalidation, or judicial review.

The best comparative formulation is therefore not “China has written description too.” It is this: Chinese Article 26(4) support performs some of the claim-scope policing work that U.S. written description performs, but it does so through the language of technical solution, sufficient disclosure, and reasonable generalization rather than possession. That distinction is not merely terminological. It is the difference between a plausible comparative article and an argument that a court, CNIPA panel, or cross-border patent team can actually use.