Why Do Examiners Fail to Recognize the Importance of my “Parameter Features”?

The Impact of Parameter Features on Inventiveness

”Parameter features” – numerical or mathematical expressions that define the quantity or physical properties of a subject – frequently appear as technical features within a claim. Often described as numerical ranges or measurements, they frequently play a critical role in addressing technical problems. However, in practice, Examiners and courts often disregard or devalue the inventive contribution of these “parameter features”, leading to considerable confusion among inventors.

Recently, the China National Intellectual Property Administration (CNIPA) released the 2023 Compilation of Key Decisions in Patent Reexamination and Invalidation Cases. Among the cases discussed, two decisions (Cases No. 24 and 25) provide valuable insights into how the parameters of chemical composition and physical properties of a subject influence the determination of inventive step.

Case No.24¹ (Reexamination Case No. 4W116011)

This case involved a polyurethane polishing pad. The distinguishing technical features between claim 1 and the closest prior art (Evidence 1) were as follows:

1. The type of curing agent (MCDEA) used was different.
2. Evidence 1 did not disclose the physical properties of the polyurethane polishing pad.

The central issue was whether the distinguishing technical features (which includes certain parameter features) should be regarded as a whole together with other components of the polyurethane polishing pad. The Reexamination Board determined that distinguishing technical features together with the other components as a whole led to an improvement in planarization and copper recess performance, and such technical effect was supported by experimental data disclosed in the specification.

The Board emphasized that when a claim includes multiple distinguishing technical features—such as chemical composition, concentration, and physical property parameters—an examiner should consider these features holistically from the perspective of a skilled person in the art, and consider whether the claimed features interact synergistically to solve the stated technical problem and achieve an unexpected technical effect.

Despite the fact that parameter features describe “measured” observable characteristics of a structure and composition (as opposed to explicit modifications of such structures or compositions), they should not be dismissed as mere claim limitations (that don’t contribute to the invention). Instead, their technical significance must be objectively examined in light of the disclosure in the specification. In this case, the claim was ultimately upheld.

Case No.25¹ (Reexamination Case No. 4W115533/4W115534)

This case involved an acidic oil-in-water emulsion liquid seasoning containing sesame. Claim 1 differed from the closest prior art (Evidence 1) in three respects:

1. pH range was 3.0–4.6.
2. contained whole sesame seeds (including seed coats) in an amount of 1%–20%.
3. included sorbic acid, with an acetic acid-to-sorbic acid ratio of 1:0.005 to 1:1.

The Board determined that:

• A skilled person in the art could readily determine an appropriate pH value based on Evidence 1.
• The amount of sesame constituted a routine selection within the field.
• Sorbic acid is a commonly used preservative.

In essence, claim 1 closely resembled evidence 1 in terms of composition, concentration, and technical effect, differing primarily in its use of parameter-based limitations.

The Board emphasized that when a claimed invention is distinguished only by numerical parameters, it is essential that the specification provide experimental data demonstrating that the specific parameter ranges cause the unexpected technical effect. In this case, the specification failed to establish how the claimed parameters influenced the composition, concentration, or performance of the product, and thus could not demonstrate that such parameter limitations produced any significant technical advancement. The claim was ultimately invalidated for lack of inventive step.

EIP Thoughts

The above cases underscore a fundamental principle in Chinese patent practice: the ability of parameter features to contribute to inventiveness hinges on whether the specification includes corresponding experimental data that links the parameter features to one or more unexpected technical effects.

At first glance, ensuring compliance with these requirements during the drafting stage may seem straightforward. However, in practice, achieving this is far more challenging.

How Much Parameter Data is Enough?

It’s one thing to draft and provide strong data demonstrating how certain parameters are linked to an unexpected technical effect. However, applicants may never be able to fully anticipate and prepare sufficient experimental data in advance. After all, it is difficult for an inventor to predict what prior art will arise during prosecution. Regardless of how much data is initially submitted, there is always a risk that different prior art is cited during prosecution, leading to the need for different types of comparison data or supporting evidence.

Additional factors can further contribute to data insufficiency:

Applicants may intentionally withhold certain experimental data to prevent competitors from easily identifying the optimal parameter range from publicly available documents. This may involve disclosing only partial or non-optimal experimental results.

Applicants may deliberately broaden the parameter ranges in their claims to obtain broader protection, even if doing so extends the claim scopes beyond the ranges for which they have robust experimental support.

The Post Filing Data Approach

In such cases, we recommend submitting undisclosed experimental data as “post-filing data” or providing experimental data in a targeted manner during prosecution while carefully adhering to the applicable restrictions², including:

The specification must describe the technical effect associated with the parameter feature. That is, while the specification may not include explicit experimental data, it must provide a clear assertion of the technical effect produced by the claimed parameter (or range). Without such disclosure, the Examiner will not accept the post-filing data because a person skilled in the art would be unable to verify whether the claimed technical effect is valid based solely on the teachings of the original application.

Post-filing data cannot be used to remedy inherent deficiencies in the original patent application. In other words, such data should only serve as corroborating evidence to substantiate facts that were explicitly or implicitly disclosed in the original specification. It cannot be relied upon to introduce new, previously undisclosed technical effects or to cure an insufficient disclosure in the original application.

Risks of Overly Broad Claims & Best Practices

It is also crucial to highlight the risks associated with claiming overly broad parameter ranges without sufficient experimental support. During prosecution or an invalidation, if a prior art reference discloses any single value within a claimed parameter range, it may anticipate or render the entire range obvious. Without experimental data to support the inventiveness of the claimed parameter ranges, the entire claim will likely fail for lack of inventive step. Expanding the parameter range (without drafting layers of back-up ranges) increases the likelihood that prior art will fall within the claimed scope, ultimately increasing the risk of rejection or invalidation.

To mitigate these risks, we recommend adhering to the following best practices when developing technology and drafting parameter-based claims:

Define parameter ranges as precisely as possible and ensure they are well-supported by experimental data.

Clearly demonstrate a significant technical distinction between the claimed parameter range and the prior art, particularly in terms of unexpected technical effects.

Consider subdividing broad parameter ranges into smaller, well-supported subranges, which enhances flexibility in claim amendments during prosecution.

Ensure that the original application includes sufficient experimental data to support the claimed parameter range and to withstand scrutiny during prosecution and potential invalidation challenges.

By following these strategies, applicants can strengthen the patentability of parameter-based claims and enhance their ability to withstand prosecution and post-grant challenges.

This article is for general informational purposes only and should not be considered legal advice or a legal opinion on a specific set of facts.

1. https://www.cnipa.gov.cn/module/download/downfile.jsp?classid=0&showname=2023%E5%B9%B4%E5%BA%A6%E4%B8%93%E5%88%A9%E5%A4%8D%E5%AE%A1%E6%97%A0%E6%95%88%E5%85%B8%E5%9E%8B%E6%A1%88%E4%BB%B6%E5%86%B3%E5%AE%9A%E8%A6%81%E7%82%B9%E6%B1%87%E7%BC%96.pdf&filename=bfb092fbe1af43608d88bdc912cd7566.pdf↩︎
2. https://ipc.court.gov.cn/zh-cn/news/view-3050.html↩︎