The Canadian Commissioner of Patents published a decision rejecting a patent application by an artificial intelligence system and naming the AI as an inventor. Keeping with established practice, the commissioner accepted the advice of members of the Patent Appeal Board that an artificial intelligence system cannot be named as an “inventor”. The applicant, Stephen L. Thaler, has for years now filed patent applications in many jurisdictions naming his AI, DABUS, as an inventor. Most patent offices have refused his applications. So the result from Gatineau surprised no one. This refusal aligns with a global judicial trend rejecting AI inventorship.
In-depth summary of re Thaler (Stephen L.) – 2025 CACP 8
The background is of interest to those wanting to understand the patent process. You can read more about commissioner decisions in “Abstract ideas need not apply: Cracking the code of Canada’s patent eligibility requirements”.
Background procedural history
Stephen L. Thaler filed a PCT application (PCT. Appl. No. PCT/IB2019/057809) in 2019 and entered the national phase in Canada as Canadian patent application No. 3,137,161 entitled “Food Container and Devices and Methods for Attracting Enhanced Attention”. He identified the AI system DABUS as the inventor. (Note this application is thematically like a distress signal device created by DABUS filed elsewhere. E.g., EP3563896 “Devices and methods for attracting attention”.)
This case was never assigned to an examiner. In late 2021, the commissioner sent a letter explaining that the application didn’t comply with the Patent Act and Patent Rules. Dr. Thaler responded in mid-2022. In 2024, the commissioner replied, informing Dr. Thaler that they were referring the matter to the patent appeal board. Something normally done after examination.
The commissioner not the examiners grant patent applications. They also refuse them so per section 40 “Whenever the Commissioner is satisfied that an applicant is not by law entitled to be granted a patent, [t]he[y] shall refuse the application”. However, “the Commissioner has no discretion independent of the Patent Act to consider the public interest when granting or denying a patent” application. Harvard College v. Canada (Commissioner of Patents), 2002 SCC 76, (“Harvard Mouse”) ¶119.
Out of fairness and to aide in their recommendation, the board held a hearing in February 2025. Dr. Thaler’s patent agent and lawyer attended. The commissioner, on advice of the board, refused the application in its decision of 2025 June 5. CIPO took another three months to publish the decision – which is a typical delay.
Central issues
The board addressed two questions:
- Can an artificial intelligence system qualify as an “inventor” under Canadian patent law?
- Could Dr. Thaler, as the owner or operator of DABUS, serve as a legal representative to rectify any inventor-identification defect?
Must an inventor be a natural person?
The patent office in 2021 maintained that the application didn’t comply with §27(2) of the Patent Act.
(2) The prescribed application fee must be paid and the application must be filed in accordance with the regulations by the inventor or the inventor’s legal representative and the application must contain a petition and a specification of the invention.
The board pointed out “the term ‘inventor’ is defined neither in the Patent Act, nor in the Patent Rules.” They note the Patent Rules (§54(1)) require an application to indicate the “name and postal address of each inventor” and therefore an inventor must be a natural person. Given that companies have names and postal addresses, this is ridiculously light reasoning. Indeed, it is almost unreasoned. But it makes no difference in the decision.
The board also held that if there is no inventor, then there can be no inventor’s representative. This is a very reasonable position.
The board reviewed the principles of statutory interpretation and then considered the definition of inventor from various dictionaries. They briefly looked at the Patent Act’s language and considered how the Act refers to “other persons” and held that this suggested an inventor was also a person.
The applicant made a weak argument. They pointed out that “calculator” and “computer” at one time referred to people and not machines. They also argued that less weight should be placed on the grammatical and ordinary meaning of the text, and more weight should have been placed on parliament’s intent.
At this point, it is very hard to imagine that this decision was written by the three members of the Patent Appeal Board with advice from only the applicant and a patent examiner. It is unclear who else was at the hearing. That isn’t to say what the board did was wrong, just possibly something they should have left to the Federal Court.
The board considered some case law on the meaning of the word inventor. They cited Sarnoff Corporation v The Attorney General of Canada, 2008 FC 712 at ¶9, which discussed the matter and cited Apotex Inc v Wellcome Foundation Ltd, [2002] 4 SCR 153 (“AZT“) at ¶s 94 to 109. This case law is relevant and supports the board’s decision, but the cited parts of these prior reasons are obiter not ratio.
Roman law
The board considered something far removed from patent law. The applicant argued he “derives entitlement to the subject-matter of the invention through the ancient Roman principle of ‘accession’.”
Accession in Roman law was a foundational principle of property acquisition by which an accessory thing (accessorius) that becomes united with a principal thing (principale) automatically falls under the ownership of the principal’s owner.
Accession could occur naturally or artificially. Natural accession included land-to-land changes such as accretion (gradual soil deposit) and avulsion (sudden land separation), as well as the growth of fruits or offspring on owned land or animals. The framer who owns the cow also owns the calf. In each case, whatever “accreted” to the principal became owned by the principal’s proprietor.
Artificial accession covered a range of human-made unions:
- Movables to movables (e.g., sewing a button onto a tunic)
- Movables to land (e.g., buildings constructed on a plot; plantations that take root)
- Specification (specificatio), where raw materials are transformed into new products (e.g., bronze into a statue). Under these scenarios, the accessory’s identity merges or disappears, and the principal’s owner gains the whole, with equitable remedies in cases of good or bad faith.
As an aside, it is fun to think of what a Roman juror would think of the output of the Antikythera mechanism, some other orrery, or analogue computer. I’d argue that accession wouldn’t apply because the predicted astronomical event would have happened without the prediction, and thus, the output of the device is something the machine owner could claim. Analogue computers are as old as our legal traditions.
Returning to the accession argument, the applicant supported their arguments with reference to case law. For example, Banque Canadienne Nationale v Tencha, [1928] SCR 26 at 36.
The board found examples from around the world where this argument had been dismissed. See, for example, Thaler v Comptroller-General of Patents, Designs and Trade Marks [2023] UKSC 49.
Policy considerations for AI inventorship
The commissioner can invoke policy considerations when granting or refusing a patent application. These are broader public interest, legislative intent, and societal goals that inform the interpretation and application of the Patent Act. They are not explicitly defined in the law but serve as a guide especially in complex cases where the law’s language is not entirely clear. A hypothetical policy consideration could be something like if the commissioner allowed AI inventors the patent office would be flooded so as a matter of policy the application should be refused. (The commissioner is not say this.)
The applicant advanced policy considerations and the board addressed them but pointed out they had not relied on policy considerations. It is a bit of a reversal for an applicant to invoke policy considerations.
AI-assisted invention
The board discussed but did not opine on the validity of AI-assisted innovations. The applicant argued that if the commissioner allowed an inventor to file a patent application for an invention where the inventor was assisted by an AI, it would be an untrue material allegation in the petition for a patent. These are fatal. So the applicant argues that since the inventor wasn’t inventing, they can’t claim to be an inventor. The board, oddly, chose not to reference settled law on the role of an inventor, such as the AZT case and dismissed the argument. Adding “there would seem to be a healthy use of AI tools in the pharmaceutical domain, and no apparent barriers to innovation or the use of the patent system.”
Thus, for all you inventors out there that use an AI as part of your invention or application process, this decision suggests the board wouldn’t have a problem with that. But remember, the reasons of the board are not binding precedent on later panels or courts. They are possibly persuasive.
Conclusion on Thaler and DABUS
Nobody is surprised by this result. The board rarely recommends the commissioner allow applications.
This is an odd case. CIPO never assigned an examiner. The commissioner waited a year to issue a letter saying the application didn’t comply with the Act and Rules. The applicant replied six months latter. Two years later, the commissioner referred the matter to the board. The issues were questions of law only. Panels of the Patent Appeal Board construe claim language, not statutes.
The commissioner has only the discretion provided to them by law and not the ability to make law. For example, in Harvard Mouse, the Supreme flat out rejected the suggestion that the commissioner could refuse the claim “by law” by invoking constitutional grounds or the like.
Now, if Thaler appeals, I suspect the Federal Court would give zero deference to the PAB/CD here. But I think if the Court were to do its own statutory construction, it would likely land on the same result.
Finally, if your company uses AI in its innovation process to help people invent, this decision doesn’t affect you.
