A recent decision from the Delhi High Court has shown that proving inventive step in India is not just about having a creative idea, but on conducting experiments carefully and sharing the results clearly. Ranjan Narula and Survana Pandey explain how well-planned experiments, thorough documentation, and clear reporting are essential to show that the invention truly offers a technical improvement and to successfully address objections based on prior arts. 

 

Saint Gobain Glass France v. Assistant Controller of Patents & Asahi India Glass (C.A. (COMM.IPD-PAT) 13/2024 Delhi High Court 

A recent decision from the Delhi High Court has shown that proving inventive step in India is not just about having a creative idea, but on conducting experiments carefully and sharing the results clearly. The dispute centres around Indian Patent Application No. 201717045317, titled “Material comprising a stack of thin layers” filed by Saint Gobain Glass, a French company specializing in glass products for architectural, automotive and industrial applications. Saint Gobain Glass is known globally for innovations in high-performance glazing, solar-control coatings, and multilayer functional glass. 

The Indian application was filed as a national phase entry under the Patent Cooperation Treaty (PCT), claiming priority from French application FR1556502 dated July 9, 2015. The corresponding European patent application was eventually granted by the European Patent Office (EPO) after undergoing examination and opposition procedures. 

In India, a pre-grant opposition was filed by Asahi India Glass (Respondent No. 2), challenging the patentability of the application. The opposition raised issues of lack of inventive step, obviousness and insufficiency of disclosure, with a focus on whether the claimed multilayer coating structure offered any technical advancement over existing knowledge in the field. 

The invention relates to a glass substrate coated with a stack of thin layers, including a silver-based functional layer, designed to achieve specific optical properties (neutral transmission colours, glossy silver reflection, high external reflection, and maintained solar performance). 

Controller’s decision and appeal 

On January 5, 2024, the Controller of Patents refused the patent application. The Controller's decision cited a lack of inventive step, asserting that the claimed invention was obvious in light of prior art. The decision relied on multiple prior arts, including international and Indian patent applications, which disclosed glass substrates with multilayer coatings containing silver and blocking layers. 

Saint Gobain Glass France filed an appeal under Section 117A of the Indian Patents Act, 1970, challenging the refusal before the Delhi High Court. The patent appeal raised key issues regarding the demonstration of inventive step, the sufficiency of experimental data, and whether the mosaicing of prior arts by the Controller constituted impermissible hindsight. 

Core issues before the appeal court 

The core issues on appeal before the Delhi High Court were: 

1. Inventive step and obviousness. Was the invention non-obvious over prior art? 

2. Technical advancement. Did the invention show technical advancement over existing knowledge? 

3. Sufficiency of disclosure. Was the experimental data adequate to support the claimed advancement? 

4. Mosaicing of prior art. Was it permissible to combine multiple prior art references to assess obviousness? 

5. Person skilled in the art (PSITA). What is the correct standard for PSITA in Indian law? 

6. Territorial patent rights. Does a foreign patent grant affect the Indian decision? (The corresponding EP patent application was granted by the EPO) 

Our analysis focuses on what is required to show technical advancement over existing knowledge and overcome the objection of obviousness over prior art: 

1. When an invention involves modifications that might appear obvious at first glance, comparative experimental results become crucial in determining the inventive step (or non-obviousness) of a patent application.  

2. The experiment results help demonstrate that the claimed invention provides a technical advantage or achieves an unexpected effect compared to the closest prior art. 

3. The applicant to overcome the objection that the invention is not merely a predictable outcome of existing knowledge in such cases must provide data based on experiments that clearly shows improved performance, enhanced properties, or surprising results.  

4. The evidence is often essential in rebutting objections raised by patent examiners and in establishing that the invention solves a technical problem in a non-obvious way.  

5. To be effective, the experimental results must directly compare the invention with the relevant prior art and clearly highlight the advantages, thereby strengthening the case for patentability. 

The court’s analysis of the technical advancement 

1. The applicant submitted comparative data based on minor differences in thickness of the layers between the claimed stack and comparative examples, highlighting that optical parameters such as light transmission (LT%), external reflection (LRext%) and colour values (aext, bext) were different in the comparative stacks. 

2. The court observed that the comparative data provided included configurations containing a lower blocking layer (LBL), which was subsequently excluded by amendment to independent Claim 1. As such, the absence of supporting data for the invention without the LBL is a material deficiency in establishing technical advancement. Since all the experiments included LBL, it was apparent that LBL is not an optional layer rather an essential layer to achieve the claimed properties. 

3. The appellant (Saint Gobain) submitted an expert affidavit for curing the above deficiency. However, the court held that the selective presentation of data, inconsistent with the broader technical objectives stated in the specification, diminishes the probative value of the affidavit and the appellant failed to demonstrate that the claimed invention, achieves any significant technical improvement over the prior art. The court stated: “The fact that an expert affidavit is filed at the appellate stage does not compensate for missing comparative experimental results in the specification. Such afterthefact data carries limited weight.” 

4. The court found that each prior art cited by the Controller pertains to the same technical field as the claimed invention namely, glazing comprising a transparent substrate coated with a stack of thin layers, including a silver-based functional layer. All the prior arts address coatings involving silver and nickel/chromium blocking layers for solar or optical control, falling squarely within the domain of the claimed invention. 

5. A person skilled in the art would naturally be motivated to consult and combine these prior arts to solve the technical problem existing at the time of filing. When all the cited prior arts pertain to the same technical field as the invention, the analysis does not constitute hindsight mosaicing but rather represents a legitimate combination of directly related teachings within the same field that a person skilled in the art would naturally consult to solve a similar technical problem. 

6. The court mentioned that “each cited prior art relates to glazing comprising a transparent substrate coated with a stack of thin layers including a silverbased functional layer … a person skilled in the art would therefore be motivated to consult and combine these prior arts in order to address the problem existing in the field at the time of filing.” 

7. The court observed that the distinguishing features relied upon by the appellant do not establish any unexpected technical advancement over the cited prior arts. When viewed collectively, the prior arts disclose all essential elements of the invention. The court held that the appellant has not demonstrated any surprising or non-obvious effect that would preclude a skilled person from combining these teachings. 

Role of European Patent Grant EP3319920B1 

The appellant relied on the grant of the corresponding European patent by the EPO, arguing that this should influence the Indian proceedings. The court, however, held that “the appellant’s reliance on the grant of patents for corresponding applications in foreign jurisdictions, including the European Patent Office (EPO), is misplaced. Patent rights are territorial in nature, and their grant in one jurisdiction does not bind the Controller in any way whatsoever.”  

The court further emphasized that “this contention is untenable as it is no longer res integra that patent rights are territorial in nature. A patent granted in one jurisdiction, such as France, has no bearing or enforceability in India, and does not entitle the applicant to a patent as a matter of right in this country. The Patent regime in every country requires an independent assessment of novelty, inventive step, and industrial applicability in accordance with its own statutory standards.”  

Therefore, the European patent grant, even after opposition proceedings, had no impact on the determination of inventive step or technical advancement under Indian law. 

Key takeaways  

The objective comparative experimental data is the best way to establish technical advancement over prior art. For comparative experiments, such as results comparing the claimed invention with respect to prior art or existing products, extra caution is necessary. These experiments should be conducted and presented carefully to clearly show a technical advancement over existing knowledge or technology. The comparative data should provide convincing evidence that the invention offers a technical advancement. 

If the claimed invention’s performance is similar to or only marginally better than prior art, it will likely fail the inventive step test. Incremental improvements must be supported by measurable data; otherwise, the enhancement may be regarded as a routine optimization, which a skilled person could derive through ordinary experimentation. This principle underscores the necessity of direct comparisons with the closest prior art, rather than presenting isolated or selective experimental results. 

Combining multiple prior art documents (mosaicing) is allowed if a person skilled in the art would be motivated to do so. The key is whether the prior arts are related to the inventive concept and whether their combination would be obvious to a skilled person. The court clarified that mosaicing is legitimate when all cited references relate to the same technical field and provide complementary teachings that a skilled person would naturally consult to solve the same problem. This ruling highlights that while applicants may argue against cherry-picking or hindsight in combining prior art, courts will assess whether the combination reflects logical problem-solving within the technical domain rather than an improper reconstruction. 

Consistency between the complete specification, claims and supporting affidavits is essential. The application should avoid any conflicting or contradictory results. Consistency in the data and results presented helps demonstrate the reliability and credibility of the invention. Conflicting results can create doubt about the validity or reproducibility of the invention. As seen in this case, the expert affidavit submitted to address deficiencies in the comparative data carried limited weight because it was inconsistent with the broader technical objectives stated in the specification. Therefore, a robust patent application must maintain internal consistency and clarity, presenting experimental results that reliably support the claimed technical advantages. This holistic approach strengthens the applicant’s position in demonstrating inventive step, ensuring that the claimed technical advancement is both credible and legally defensible. 

In simple terms, the court’s observations highlight that proving an inventive step is not just about having a creative idea, rather it depends on conducting experiments carefully and sharing the results clearly. Well-planned experiments, thorough documentation, and clear reporting are essential to show that the invention truly offers a technical improvement and to successfully address objections based on prior arts. 

Asahi India Glass Limited, Respondent No. 2, was represented by the team of patent attorneys from RNA, IP Attorneys, both before the Delhi High Court and as the opponent in the pre-grant opposition proceedings before the Indian Patent Office.