Have you received a patent infringement letter?

No one likes receiving a letter claiming that they, or their business, are infringing a patent. It is typically a surprise, and almost always disruptive. So, what should you do if you ever receive one? Well, there are two things you shouldn’t do: (a) don’t panic; and (b) don’t ignore it. Consulting an IP professional is the best way to avoid either response.

Patent owners will typically seek for you to either stop engaging in a particular conduct (e.g. selling a particular product) or pay a licence fee to continue that activity. In response the alleged infringer would typically have several options:

  1. demonstrate that the conduct does not infringe the patent;
  2. demonstrate that the patent is invalid and cannot be enforced; or
  3. failing options (a) and (b), comply with the patent owner’s demands, and either stop the conduct or negotiate a licence.

Is your conduct infringing the patent?

Let’s say the relevant conduct relates to sale of a particular product. Does this product actually infringe the patent? This requires a comparison of ‘claims’ found in the patent document against the features of the product.

To infringe any claim of the patent, the product will need to take all essential features of that claim. So, if a claim requires a product to be made of metal, but your product is made of plastic, then your product does not fall within that claim. Similarly, if a claim requires a product to include a handle, but your product has no handle, then your product does not fall within that claim.

It should be noted at this stage that a patent will typically comprise many claims of varying specificity, and your product would only need to fall within one claim to potentially be infringing a patent. However, this remains a matter worth detailed consideration, i.e. – does your product or conduct actually infringe the patent?

If your product does fall within one or more claims of the patent, what then?


Is the patent valid?

Patents are granted following a process of examination in which patent offices will seek to confirm whether an application is suitable for grant of a patent before it is granted. This will include a check for whether an invention claimed is actually new and inventive.

To check the above, patent offices will conduct a search of the internet and various databases to confirm that no one else has already thought of the same invention, or a similar invention, before the ‘priority date’ of the patent application.

It should go without saying that patent offices may miss evidence that an invention is not actually new and inventive. For a start, patent examiners are human and can miss relevant issues. Also, certain documents and other evidence may simply have been unavailable to a patent office when an application is examined. In short, you should not assume that a patent is valid just simply because it has been granted.

Where may you find evidence that an invention claimed is not actually new or inventive? Three sources immediately spring to mind:

  • your own backyard – when did you start developing / making your product? Was it before the priority date of the patent? If so, your own product may actually invalidate the patent;
  • existing patent office citations – has relevant earlier evidence been uncovered by another patent office, or has that review by the patent office been overlooked? It is always worth a review of documents referenced during patent office search and examination reports;
  • private searching – can a further document search uncover a document or other evidence that the patent office missed?

It is also always worth noting that the law may have changed since the patent was granted in such a way the patent is now invalid. For example, if the invention relates to a computer-implemented business method then the law in this area has moved over the last few years such that the validity of any patent relating to this field is worth analysing.


Can you modify your product or conduct to avoid the patent?

Failing the above it is also worth considering whether your product or conduct can be easily modified to avoid the patent. Turning again to the above examples, you can ask yourself whether your product truly needs a handle, or truly needs to be made of metal. Often logistics will get in the way of making any fast changes (e.g. you have a back order or contractual obligations which prevent you from modifying your product); however, it is also worth considering before progressing down the licensing route.



Patent infringement notices should never be ignored, but in the same token may not provide a reason to panic. Before agreeing to a licence, or to stop your present activities, a timely and reasoned analysis of your options could determine there has in fact been no patent infringement, that the patent is invalid anyway, or that minimal changes can be made to avoid continued patent infringement.



For assistance and/or further information, please contact:

Rhys Munzel
(03) 9642 2252

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