The legal tests for novelty, inventive step and, less commonly, industrial application form the basis of the majority of patent litigation before the UK courts. However, well before a patent becomes the subject of litigation in the UK, its subject matter has already been assessed by the UK or the European Patent Office during prosecution to ensure that it satisfies the requirements for patentability. In the UK, these requirements can be found in s1(1) of the Patents Act 1977.

Whilst the requirements for patentability are well documented, the standard to which an applicant must establish patentability is less so. The nature of the standard of proof for patentability was recently considered in Blacklight Power Inc v The Comptroller-General of Patents by Mr Justice Floyd in the Patents Court.1


The case concerned an appeal by Backlight Power Inc from a decision of the Hearing Officer to reject two of its patent applications. The patent applications related to a plasma reactor which generates power and a novel hydrogen species and a laser operated by the same hydrogen species. Both applications were based on the inventor's "Grand Unifying Theory of Classical Quantum Mechanics", which was shorted in the Judgment to "GUTCQM".

The examiners of the applications objected to the subject of the applications on the basis that aspects of the invention were contrary to generally accepted physical laws and therefore not capable of industrial application as required by s1(1)(c) of the Patents Act. The examiners also objected on the basis that the specification did not comply with the requirement of sufficiency in section 14(3) of the Patents Act.

Decision of the Hearing Officer

In upholding both of the examiner's objections, the Hearing Officer identified the question which he had to address to be whether the underlying theory of GUTCQM was true. In doing so, he identified three criteria which he had to consider in determining whether a scientific theory was true, namely whether:

  1. the explanation of the theory is consistent with existing generally accepted theories. If it is not, it should provide a better explanation of physical phenomena then current theories and should be consistent with any accepted theories that it does not displace;
  2. the theory makes testable predictions, and the experimental evidence shows rival theories to be false and matches the predictions of the new theory, and whether
  3. the theory is accepted as a valid explanation of physical phenomena by the community of scientists who work in the relevant discipline.

Critically, the hearing officer went on to determine that he must satisfy himself that it was more probable than not that the theory was true. On this basis, the Hearing Officer found that he was not satisfied that the theory was true and therefore the claims in the applications which relied upon the theory were not patentable.

The Appeal

The appeal focused on whether the Hearing Officer had been right in considering the appropriate test to be whether the theory was true on the balance of probabilities. Blacklight contended that the test that should be applied is whether the theory is clearly contrary to well established physical laws. In considering this, the examiner should assess whether the applicant has a reasonable prospect of showing that his theory is a valid one should the patent be litigated in court. In making these arguments, Blacklight accepted that on the material before the Hearing Officer the theory was probably incorrect.

In considering the case Floyd J noted previous decisions of the Patents Court and Court of Appeal which indicated that during prosecution the benefit of the doubt should be given to the applicant, on the basis that a refusal to grant a patent based on a faulty appreciation of what was involved cannot be thereafter remedied. At the same time Floyd J recognised that if there is substantial doubt then the burden had not been fulfilled. In coming to the conclusion that the approach that had been applied in previous cases was in accordance with the statutory framework, he remitted the cases to the Patent Office to consider whether there is a reasonable prospect that on a full investigation with the benefit of expert evidence, GUTCQM would turn out to be a valid theory.


It is clear from this case that in assessing the validity of a patent, if an examiner is in doubt about an issue of fact which could lead to patentability, he should consider whether there is a reasonable prospect that the doubt will be allayed if the issue is fully investigated at trial. Examiners therefore need to anticipate the benefit of expert testimony and, where necessary, the results of any experiments carried for the purpose of the litigation. At the same time, the Court was careful to point out that it is not the law in the UK that any doubt, no matter how small, on an issue of fact would force the Patent Office to allow an application to proceed to grant. As Mr Justice Floyd commented "...mere optimism and a reasonable prospect of matters turning out differently are not the same thing." It is clear therefore that examiners will continue to perform a balancing act between giving patent applicants the benefit of the doubt and preventing the granting of patents for subject matter which does not satisfy the requirements of patentability.


1. [2008] EWHC 2763 (Pat)

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