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Thaler v Comptroller General of Patents, Trade Marks and Designs: Court of Appeal Judgment on Machine Inventors

The Court of Appeal (Arnold LJ, Laing LJ and Birss LJ) handed down its judgment in Thaler v Comptroller General of Patents Trade Marks And Designs on 21 September 2021. The court held, with Birss LJ dissenting, that the judge of first instance (Marcus Smith J) was correct in his dismissal of the appeal.

The appellant, Dr. Thaler, had originally applied for two patents at the UKIPO, listing his artificial intelligence (“AI”) machine DABUS as the inventor for both. The UKIPO found that DABUS is not a person as envisaged by s. 7 and s. 13 of the UK Patents Act 1977 (the “1977 Act”) and so cannot be considered an inventor, and that Dr. Thaler had not provided a satisfactory derivation of his right to be granted the patents. The patent applications were therefore deemed withdrawn. Dr. Thaler then appealed this decision to the High Court, where his appeal was dismissed by Marcus Smith J.

This case is notable because it considers whether a machine can constitute an inventor for the purposes of UK patent law. In the context of advanced artificial intelligence, this question is becoming increasingly relevant. Many companies now own technology that may broadly be described as AI, and such technology is often used during the creation of inventions.

The court’s unanimous decision was that nonetheless an AI machine cannot be an “inventor”. Indeed, the court ignored all policy arguments for and against machine inventorship, and simply proceeded with textbook methods of statutory interpretation. Their finding thereby indirectly confirms that the existing practice of naming a human as the inventor of any patentable output produced by AI remains the most commercially sound option. The court was split 2-1 (Birss LJ dissenting), however, as to the formal issues of how to correctly process patent applications through the Patent Office when an applicant identifies an AI machine as the inventor and their ownership of an AI machine as the basis for being entitled to the grant of a patent.


Section 7: Machine Inventorship

Turning first to the issue of machine inventorship, the court unanimously found that the inventor of an invention under the 1977 Act must be a natural person. The court was not asked to consider whether DABUS actually invented the claimed technology, or even if the invention is worthy of a patent. The issue at hand relates specifically to whether a machine can be considered an inventor under UK patent law. The relevant legislation is s. 7 of the 1977 Act, which states:

Right to apply for and obtain a patent.

(1) Any person may make an application for a patent either alone or jointly with another.

(2) A patent for an invention may be granted—

(a) primarily to the inventor or joint inventors;

(b) in preference to the foregoing, to any person or persons who, by virtue of any enactment or rule of law, or any foreign law or treaty or international convention,
or by virtue of an enforceable term of any agreement entered into with the inventor before the making of the invention, was or were at the time of the making of the invention entitled to the whole of the property in it (other than equitable interests) in the United Kingdom;

(c) in any event, to the successor or successors in title of any person or persons mentioned in paragraph (a) or (b) above or any person so mentioned and the successor or successors in title of another person so mentioned; and to no other person.

(3) In this Act “inventor” in relation to an invention means the actual deviser of the invention and “joint inventor” shall be construed accordingly.

Birss LJ, in finding that machines are not inventors within the meaning of the 1977 Act, relied heavily on his interpretation of the term “actual deviser” from prior legislation. Birss LJ, through his own research, identified that this term was actually taken from s. 16 of the Patents Act 1949, where it specifically meant the person who actually devised the invention. Therefore, together with the express wording of s.7 in the 1977 Act referring to “person” in various instances, Birss LJ concluded that the inventor had to be the person who actually devised the invention.

Arnold LJ, with whom Laing LJ agreed, instead applied a systematic interpretation of the surrounding provisions in the 1977 Act, but nonetheless reached the same conclusion. Arnold LJ applied the dictionary definition of “deviser” and found it to mean “a person who devises; a contriver, a planner, an inventor”. In addition, similar to Birss LJ, Arnold LJ relied upon the various reference to “person” in s. 7 of the 1977 Act. On his reading, it is plain that only a person can fall within the ambit of section 7.

As such, given that an AI machine is not a person, it cannot be an inventor for the purposes of the 1977 Act, irrespective of whether a machine has actually created the invention.


Section 13: Mention of Inventor

Separately to claiming that DABUS could constitute an inventor, Dr. Thaler also brought his appeal on the grounds that the UKIPO had misapplied s. 13 of the 1977 Act. S. 13 provides:

Mention of inventor.

(1) The inventor or joint inventors of an invention shall have a right to be mentioned as such in any patent granted for the invention and shall also have a right to be so mentioned if possible in any published application for a patent for the invention and, if not so mentioned, a right to be so mentioned in accordance with rules in a prescribed document.

(2) Unless he has already given the Patent Office the information hereinafter mentioned, an applicant for a patent shall within the prescribed period file with the Patent Office a statement—

(a) identifying the person or persons whom he believes to be the inventor or inventors; and

(b) where the applicant is not the sole inventor or the applicants are not the joint inventors, indicating the derivation of his or their right to be granted the patent;

and, if he fails to do so, the application shall be taken to be withdrawn.

In his patent application, Dr. Thaler’s response to s. 13(2) (a) was to identify a non-person inventor in DABUS, and his response to s. 13(2)(b) was to assert that he derived his right to grant from his ownership of DABUS.

In their interpretation of this section, Arnold LJ and Laing LJ found that Dr. Thaler had failed to comply with s. 13(2)(a) and (b) because his responses were legal impossibilities, and therefore the withdrawal of his application was an inevitability.

On s. 13(2)(a), it is not possible to comply with this section by not identifying a person and instead positively asserting that the inventor is not a person. Both judges referred to the above analysis on machine inventorship, noting that s. 7 clearly requires an inventor to be a person. Therefore, refusing the application on these grounds was not an example of the Patent Office examining an applicant’s claimed entitlement, but was the natural result of non-compliance.

On s. 13(2)(b), Arnold LJ and Laing LJ also both found that Dr. Thaler had failed to properly indicate the derivation of his right, because the rule of law that he invoked does not exist.

Dr. Thaler attempted to claim that he derived his right to entitlement under s. 13(2)(b) because he owned DABUS, and therefore he owned any output that DABUS produced. This is the common law doctrine of accession. In essence, where one piece of property produces another piece of property, the owner of the former will generally own the latter by virtue of exclusive possession (e.g. the owner of an apple tree will also own the fruit of the tree).

However, the court held that such a doctrine has never applied where a piece of property produces intellectual property. This is because intellectual property is not susceptible to the doctrine of exclusive possession. An unlimited number of parties can use an invention simultaneously. On this basis, applying much the same logic as with s. 13(2)(a), Arnold LJ and Laing LJ also found that Dr. Thaler had therefore failed to comply with his statutory duty under s. 13(2)(b) by indicating a derivation that was legally impossible.

Birss LJ, dissenting from the majority, found that Dr. Thaler had in fact complied with his obligations under s. 13(2) and allowed the appeal on these grounds. He noted that the purpose of s. 13 was not to provide a mechanism for the Patent Office to evaluate the accuracy of the information on inventorship and entitlement, but was simply to provide information that will be made public. Birss LJ found that Dr. Thaler had complied with his statutory duty by providing the information sought.



In terms of actually protecting inventions that AI technology were used to create, this judgment confirms the practice of naming the humans that are responsible for devising inventions where the inventive process has involved the use of AI technology. Birss LJ actually stated that: “if only Dr Thaler was not such an obsessive and, instead of calling DABUS the inventor, he named himself then none of these problems would arise.”1 Indeed, some organisations have already adopted this strategy.

However, Dr. Thaler’s reasons for bringing the case were not about protecting a potentially valuable piece of intellectual property, but were instead about actively attempting to change the law on machine inventorship. For the proponents of this concept, the present case has undoubtedly confirmed that parliament, as opposed to the courts, is the proper forum to effect such change. As Arnold LJ observed, “modern patent law is almost entirely a creature of statute”.2


Thaler v Comptroller General of Patents Trade Marks And Designs [2021] EWCA Civ 1374 (21 September 2021), Paragraph 81.
Thaler v Comptroller General of Patents Trade Marks And Designs [2021] EWCA Civ 1374 (21 September 2021), Paragraph 136.


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