IP Information & News

How to throw a spanner in the works for patent applicants — third party observations 101

Jonathan Higgs

By Jonathan Higgs

Senior Patent Attorney

If there is a pending patent application that is causing you some anxiety, either for a competitor’s invention that is barely unique or an invention that is different in practice, but has an incidental similarity to your own, then third party observations (TPOs for short) could be a cost effective way to influence examination of the application before a patent is granted. That influence could be to force an amendment that will take your product out of the claim scope and hence avoid infringement; or sink the patent application entirely.

Here are the basics of TPOs in two major territories.


The European Patent Office (EPO) provides an online form for anyone to make submissions on a pending patent application. The submission could be anonymous – just make sure to avoid using letterhead or any other tell-tale signs of identity within the documents...

The trick with TPOs is making the submissions convincing so that a patent examiner will take them seriously. This is where your patent advisor will be invaluable. A highly relevant prior document may be available, but the examiner could overlook its relevance if a coherent argument is not prepared using a format that the examiner is familiar with. The examiner is obliged to review the submission but might quickly discard it if it is not clear on a first reading that a current claim is invalid for some compelling reason.

Typically, the best evidence for knocking out a patent will be on the basis of a printed document, publicly available before the patent’s filing date. A prior patent document works best, but any published document, like a journal article or research paper, can be just as successful. What does not tend to be successful in the context of TPOs is asserting invalidity on the grounds of “prior use” where extensive evidence is needed to establish that a disclosure took place before the patent’s filing date. If the submission gets too complicated then the examiner will likely ignore it, because such issues are more appropriately tackled during a formal opposition procedure, following grant of the patent.

The best time to file TPOs at the EPO is at some point between becoming aware of the application and before a first examination report is issued. Submissions can be validly made right up until grant, but the impact will naturally diminish at the later stages of examination when the examiner will be reluctant to raise entirely new objections.


The opportunity for third-party submissions before grant of a patent at the US Patent and Trademark Office (USPTO) is more limited. In fact, there is only a narrow window; the earlier of:

a) the date a Notice of Allowance is issued; or

b) if the application has not been allowed yet, the later of (i) six months after the date on which the application is first published by the USPTO, or (ii) the date of the first rejection of any claim by the examiner during examination.

In other words, a US examiner wants to see submissions from a third party before substantive examination has taken place, so they do not duplicate effort.

The current US system, while limited, is an improvement over previous provisions where you could only submit third party observations in any application prior to publication, i.e. you would need to have inside information about the existence and filing data of the application in order to take action.

A notable alternative to TPOs in the USA is to supply relevant prior art documents directly to the patent applicant. The applicant is under an obligation to disclose these to the USPTO before grant. Of course, the applicant is unlikely to make damaging written submissions that accompany the prior art, but at least the examiner will review those documents.

This tactic is not available in Europe where there is no duty to disclose relevant documents known to the applicant.

Cuts both ways — what if you are on the receiving end of third party observations?

If you receive third party observations on your own patent application, these can be treated like any other prior document that comes up during examination. You and your advisor will need to review the document and arguments, assess the relevance and decide whether it merits a response. If the examiner adopts some of the TPOs as part of an examination report, then you will need to address that in a formal response.

The third party can maintain a watch on the official file and elect to file further TPOs in an attempt to further influence the outcome of prosecution (at least in Europe where there is no time limit), but will not be actively invited by the patent office to take part in proceedings.

After grant

The formal procedure for revoking a patent at the EPO is known as ‘opposition’; available up to 9 months from grant. Both the patentee and opponent actively participate in this process, up to and including a formal hearing. The cost of EPO opposition varies widely depending on complexity of the issues, but will be considerably more expensive than TPOs.

Before the USPTO patents can be challenged after grant by Third Party Review, which must be filed within nine months. The cost will be many times that of TPOs. After nine months, there is an option known as Inter Partes Review, but the cost is also very high.

From the above it is evident that getting in early, while the patent is still pending, and filing convincing third party observations could be a considerably cheaper way of limiting a competitor’s patent, to the extent that it is no longer a threat to your business.

If you need help filing patent applications, prosecuting existing ones or you are interested in filing TPOs against a known problem patent application, get in touch with me at jgh@udl.co.uk.

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