Quote from Martin Schweiger on June 13, 2026, 11:09 pm

No, filing a 3rd-party observation at the EPO is not useless. But it is often misunderstood.

A 3rd-party observation allows anyone to submit prior art or other objections against a pending European patent application. The EPO is obliged to consider relevant observations.

However, there are some limitations:

• The observer does not become a party to the examination proceedings.
• The observer has no right to participate further or appeal decisions.
• Many 3rd-party observations result only in additional examination or claim amendments rather than the refusal of the European Patent application.

Whether filing a 3rd-party observation makes sense depends on the objective:

Good reasons to file

• Bring highly relevant prior art to the examiner's attention.
• Encourage closer scrutiny of a pending application.
• Potentially narrow claim scope before grant. This happens rather seldom, but there are cases where that happens.
• Influence prosecution at relatively low cost.

Reasons for caution

• You lose control over how the EPO and the applicant deal with the submission.
• Prior art disclosed during examination has less strategic value in later opposition proceedings. Better keep your gun powder dry.
• A 3rd-party observation does not provide Freedom-to-Operate.

In short: a 3rd-party observation is neither useless nor a silver bullet. It is simply one tool among many in European patent strategy, and whether it is worthwhile depends on the circumstances and the overall objective.

Further Aspects

Most people think of third-party observations (Art. 115 EPC) only as a way to submit prior art, but in practice, they can serve several different strategic purposes.

But one can use the 3rd-party observation not only for challenging novelty or inventive step before grant.

Sometimes the most effective attack is not the prior art itself but the priority claim.

Examples:

• Applicant claims priority from an earlier application.
• You argue the priority document does not disclose the claimed invention.
• Priority is lost.
• New prior art becomes available.

This can be devastating if successful.

Challenge Added Matter (Art. 123(2) EPC)

You can point out that claims contain features not directly and unambiguously disclosed in the original application.

Added matter objections can be difficult to overcome.

Challenge Sufficiency (Art. 83 EPC)

Argue that the invention cannot be carried out by the skilled person, for example because key technical information is missing. This is less common, but occasionally very powerful.

Challenge Clarity or Support of the claimed matter (Art. 84 EPC)

Although clarity is usually not the strongest attack, observations can highlight vague terminology, unsupported claim breadth, or inconsistencies.

This may force narrowing amendments.

Draw Examiner's Attention to Related Proceedings

For example corresponding US claims rejected, Chinese application invalidated, or Japanese examiner found relevant prior art.

Examiners do not always discover these developments themselves.

Force Prosecution History

Sometimes the goal is not rejection. Instead make applicant take positions on record, force explanations, or obtain narrowing statements.

Those statements can later become useful in opposition, litigation, or claim interpretation disputes.

This is common in the US and occasionally relevant in Europe.

Delay Grant

Not officially, of course. But in practice, a substantial observation often triggers additional examination which may delay grant.

This can be valuable if a competitor is about to obtain broad claims, if you need time for product launch, or if you want more time to prepare an opposition.

Anonymous Market Signalling

Because observations can be filed anonymously, a company can indirectly communicate that someone is watching this application. The applicant suddenly learns that a third party considers the application important.

Sometimes that alone influences prosecution strategy.

Influence SEP or Standards-Related Portfolios

In telecom, smart cards, RFID, NFC, etc., a company may file observations to narrow claims, reduce future SEP leverage, or create examination records regarding essentiality.

Defensive Publication Effect

This is a subtle use: if you have discovered relevant prior art and want to ensure it is formally in the EPO file history, a TPO creates a documented record that the art was identified, the examiner had access to it.

This can become relevant later when discussing validity.

The most underrated use

In my view, the most sophisticated use is forcing claim amendments before grant.

A granted patent with narrow claims is often much easier and cheaper to live with than:

• a broad patent that must later be opposed,
• litigated,
• or invalidated.

That is why many experienced practitioners view TPOs not as a substitute for opposition, but as a pre-opposition shaping tool.

The key question is always:

Is the value of influencing examination now greater than the value of keeping your best arguments and evidence for later?

That trade-off is what drives most strategic decisions on whether to file a third-party observation.