While browsing patents.google.com I stumbled on this invention that was patented in 2020. Its a repellent that's primarily based on the bitterant Denatonium and can be used to make certain plants unedible for pests. However this particular invention is not exactly novel because people have been aware of Denatonium's repellent properties for a long time before 2020.

Two of the main conditions for filing a patent are that the invention must be:

  1. Novel: The idea must be new and not disclosed or publicly available before the date of filing. It should not have been previously patented, published, or in public use or on sale.

  2. Inventive/Non-obvious: The idea should involve an inventive step or be non-obvious to a person skilled in the relevant field. This means it must not be something that would be considered obvious or easily deducible by someone knowledgeable in the field.

(source ChatGPT).

There are examples of people already using this substance as a pest repellent before 2020. For instance this internet article from 2018 states that Bittrex (which is the brand name for Denatonium) can be used to repel rabbits. There's even a patent filed in 2006 for a similar product that is based on asphalt and denatonium benzoate and helps prevent animals from damaging trees or other exterior surfaces.

So how is it possible that someone else was able to file another patent for a similar denatonium based animal repellent in 2020? Is it because the patent has an increased scope? I've read that it can also be used for snake and snail repellent.

  • I’ll look into this more when I have time, but for now I’d like to point out that the linked document is only an application, not a patent. It may not be granted.
    – Eric S
    Commented Jun 11, 2023 at 20:33

1 Answer 1


First of all, the cited document is an application, not a patent. Applications do not necessarily get granted and even if they do, it is common for the claims to be narrowed.

With respect to the US patent you listed as potential prior art, it patents the use of denatonium as an animal deterrent. WO2020170186A1 is claiming the use of denatonium as an insect repellent. This is not unlike developing a drug to cure one disease, and late discovering it has value treating a different disease. You can get separate patents for both indications. There is the question as to whether using a compound for repelling mammals, reptiles and snails makes it obvious that it can also be used to repel insects. I won't pass judgement on this, but the patent examiner will. In any case, if you could find a document (not just in patent literature) disclosing the use of denatonium to repel insects prior to the filing date of WO2020170186A1 that that would clearly be prior art.

  • if you could find a document (not just in patent literature) disclosing the use of denatonium to repel insects prior to the filing date of WO2020170186A1 that that would clearly be prior art.. Here's a research paper from 1995 that describes the antifeeding effect of denatonium on aphids. I understand the patent hasn't been granted yet, but aren't their rules for applying for a patent too?
    – Maurice
    Commented Jun 12, 2023 at 20:27
  • 1
    @Maurice That looks like a good example of prior art. There may be ways to provide that reference to the European and US patent offices. The patent examiner may or may not find it themselves. I believe there are other questions/answers related to the process for third parties to present prior art to patent offices. I'm pretty sure it depends on where in the process a patent application is. Or else you could present a new question.
    – Eric S
    Commented Jun 13, 2023 at 3:51

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