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22
2025-12
The Risk of “Self-Suggesting” Technical Problems
Introduction
A fundamental but often underestimated issue in inventive step analysis is that the way the technical problem is defined may, silently and decisively, predetermine the answer. A recent judgment of the Supreme People’s Court of China (SPC) provides a particularly instructive illustration of this risk.
Background of the Case
On 13 November 2025, the SPC rendered its final administrative judgment in case (2023) Zui Gao Fa Zhi Xing Zhong No. 1164, concerning Japanese Steel Corporation’s invention patent entitled “Austenitic Stainless Steel tube with Excellent Steam Oxidation Resistance and Method for Manufacturing the Same” (Chinese patent No. ZL03119950.X). Claim 1 concerns an austenitic stainless steel tube defined by specific compositional ranges of elements such as C, Si, Mn, Cr, Ni, Ti, Nb, Al, N, and O, combined with a fine-grained microstructure (grain size number ≥ 7).
The patent was challenged for lack of inventive step based primarily on prior art document D1 (JP H07-258801 A), which discloses an Fe-Cr-Ni alloy with good corrosion resistance and workability. Certain embodiments of D1 overlap with the claimed invention in terms of Ti, O contents, and grain size, but D1 does not disclose the addition of Nb.
The China National Intellectual Property Administration (CNIPA) initially upheld the patent, reasoning that the claimed invention achieved its technical effects through a specific synergistic control of Nb, Ti, and O, leading to the formation of composite precipitates with Ti₂O₃ cores surrounded by Nb carbonitrides—an idea not taught by the prior art.
The first-instance court annulled that decision. On appeal, the SPC affirmed the annulment, focusing in particular on deficiencies in how the inventive step analysis had been conducted.
Key Reasoning of the SPC
The SPC emphasized that, absent special circumstances, inventive step should be assessed using the standard three-step framework, including:
1. identifying the closest prior art,
2. determining the distinguishing features, objectively determining the technical problem actually solved by those distinguishing features, and
3. assessment of technical motivation.
In the SPC’s view, the CNIPA failed to properly articulate the “technical problem actually solved” before concluding that no technical teaching existed in the prior art.
After identifying the distinguishing features—most notably the presence of Nb and a defined lower limit for oxygen content—the Court characterized the technical problem as:
how to generate composite precipitates consisting of Nb carbonitrides precipitated around Ti₂O₃ cores.
Since D1 did not disclose Nb, treated oxygen merely as an impurity, and pursued a different technical concept, the SPC found no motivation for the skilled person to arrive at the claimed solution.
Discussion: The Risk of a “Self-Suggesting” Technical Problem
In both Chinese practice and comparative jurisdictions, it is well accepted that the technical problem should be objectively derived from the technical effects of the distinguishing features, rather than being formulated to include the solution itself. Otherwise, the problem formulation becomes the strongest possible technical hint.
In the present case, defining the technical problem as “how to generate composite precipitates with Ti₂O₃ cores and Nb carbonitrides” raises methodological concerns.
For a skilled person, such a problem formulation almost inevitably points toward introducing the missing element—Nb—into the alloy system of D1 and adjusting its content accordingly. The absence of an explicit teaching in D1 about such precipitates does not, by itself, negate the motivation to explore known alloying elements once the problem is framed in this way.
More fundamentally, the formation of the composite precipitate is not the ultimate technical goal, but merely an intermediate mechanism.
As recognized by the Court itself, the value of these precipitates lies in their effects:
- they provide grain-refining effects comparable to conventional Nb or Ti carbonitrides; and
- they resist re-dissolution at high temperatures, allowing a fine-grained structure to be maintained during welding or high-temperature bending.
Seen in this light, the invention is not truly directed to how to form a particular precipitate, but to a higher-level and more engineering-relevant problem:
how to obtain a homogeneous fine-grained microstructure that remains stable under high-temperature processing conditions.
When the problem is formulated at this level, neither D1 nor common general knowledge provides a clear technical teaching that such stability could be achieved by deliberately forming Ti₂O₃-based Nb carbonitride composite precipitates in an austenitic stainless steel tube. Under this problem framework, the claimed solution more convincingly demonstrates its non-obvious character.
Concluding Remarks
This case offers a valuable illustration of how inventive step analysis can hinge on the formulation of the technical problem. In fields such as metallurgy and materials science—where mechanisms, microstructures, and intermediate phenomena are frequently described—it may be tempting to incorporate such mechanisms directly into the problem definition. Doing so, however, risks transforming the problem itself into a technical suggestion. The purpose of this commentary is not to dispute the final outcome of the judgment, but to highlight a methodological point of broader relevance:
the level of abstraction at which the technical problem is defined can silently shape the entire inventive step analysis.
Once the problem is over-specified or framed in terms that already contain the solution, the assessment of inventiveness may, in a logical sense, have already been decided.
Avoiding this form of “self-suggestion” remains one of the most critical—and most underestimated—tasks in inventive step evaluation.
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