Assessment of Inventive Step under UK Patent Law

Kiran S Bettadapur

November 2, 2025

The House of Lords’ judgment in the Technograph Printed Circuits Ltd. v. Mills & Rockley (Electronics) Ltd. and Others (1972)[1] case is a seminal authority on assessing inventive step (or, non-obviousness). The ruling provided a structured and practical approach for courts to determine whether a claimed invention entails an inventive step or is merely an obvious application of existing knowledge to a skilled person.

Case Background

The appellant, Technograph Printed Circuits Ltd. owned a patent in respect of methods for producing printed circuit boards, using a laminate composed of a thin metal foil bonded to an insulating base by an adhesive layer. The innovation lay in the choice and combination of materials and the technique of bonding, which was claimed to produce an improved product suitable for mass production.

The defendants, Mills & Rockley (Electronics) Ltd., were accused of infringing the Technograph patent. Respondent, Mills & Rockley denied infringement and counter-claimed for revocation of the patent on the ground of obviousness.

The defendants’ arguments hinged on the contention that the invention merely applied known methods and materials in an expected manner. Prior art was cited to demonstrate the use of similar laminates and adhesives in related contexts. The essence of their counter was that any competent engineer in the field would have arrived at the claimed combination as a matter of routine experimentation.

The trial court and the Court of Appeal ruled that the claimed invention was obvious.

Hence, Technograph appealed to the House of Lords.

Issue Before the House of Lords

The central question before the House of Lords was:

"Whether the claimed invention involved an inventive step, or whether it would have been obvious to a person skilled in the relevant art in light of the prior art."

Final Verdict and Rationale

The House of Lords dismissed the appeal, affirming that the claims lacked an inventive step.

Lord Reid, Lord Morris, and Lord Diplock each offered guidance on the proper approach to determining obviousness. The Lords emphasized that while hindsight must be avoided, the ultimate test is a practical question of fact and degree, based on what a notional “person skilled in the art” would have done at the priority date.

Describing the hypothetical skilled person as "skilled, but unimaginative”, the judgment clarified that, while combining prior artis permissible to demonstrate obviousness, this "mosaic" must be one that such an unimaginative person could assemble without inventiveness.

It was further enunciated that when examining obviousness, unlike novelty, it is surely permissible to make a "mosaic" out of the relevant documents. However, such ‘mosaicing’ must be put together by an unimaginative man with no inventive capacity.

Critical Legal Principles Elaborated on

  1. The “Person Skilled in the Art”: The assessment of inventive step is made from the perspective of an ordinary practitioner in the field, who is neither a genius nor a dullard, but possesses ordinary technical knowledge and skill. It is also assumed that such an imaginary ‘skilled technician’ is well acquainted with workshop technique and has carefully read the relevant literature. While having unlimited capacity to assimilate the contents of prior art, he is  incapable of even a scintilla of invention.
  2. Avoiding Hindsight: The court must put itself in the shoes of such person skilled in the art at the time of filing of the claimed invention and seek answer to the question: “Would this solution have been obvious to try at that time?
  3. Combination of Known Elements: An aggregation or sequencing of known elements in prior art is not patentable unless their combination yields a new or unexpected result. The fact that the combination works better does not automatically confer inventiveness if such improvement was predictable.
  4. Practical Test for Obviousness: A common-sense test was also proposed. If the steps leading to the invention would have been taken by a skilled worker facing the same problem with the available materials and methods, then the invention is obvious.
  5. Secondary Considerations: Commercial success, long-felt need, or failure of others may support inventiveness, but they cannot substitute for the absence of a genuine inventive step.

Significance and Legacy

The Technograph case remains a cornerstone of UK patent law; the case cemented the foundational definition of “skilled person”. It affirmed that ascertainment of non-obviousness is a matter of not abstract logic, but practical judgment.

Novelty applies even to the adaptation of a known process for producing a new article. If there is an earlier specification for the very same ‘new article’, then the second invention is not new. On the contrary, if the two things are different, then nature and extent of differences have to be considered for establishing novelty.

 

The decision influenced later leading cases such as Windsurfing International Inc. v. Tabur Marine (Great Britain) Ltd. (1985)[2], which formalized a step-by-step test derived from Technograph, and Pozzoli v. BDMO SA (2007)[3], which refined that approach.

In essence, Technograph established that patent protection is reserved for true technical advances, not for routine workshop modifications of known technology. The judgment balanced the need to reward innovation against the public interest in keeping obvious enhancements free and accessible for all to use and benefit from.

At Blaze Ventures, we have qualified professionals and elaborate processes for helping enterprises and inventors file patent applications for ‘non-obvious’ ideas, innovations and inventions.

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[1] [1972] RPC 346 (HL)

[2] [1985] RPC 59

[3] [2007] EWCA Civ 588

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