Opposition before the granting office: stages and deadlines
Opposition is the built-in challenge to a patent grant, filed with the office that granted it rather than with a court. It runs on the office's own calendar, has fixed stages, and ends with a decision the office can maintain, amend or revoke. Missing a stage costs more than missing a court date, because opposition offers no separate action to fall back on once the window closes.
The route is distinct from a later revocation action, which sits outside the granting office and follows its own calendar entirely. Confusing the two is the most common reason a file arrives at the wrong stage of the wrong procedure.
What changes once an opposition is filed
A pending opposition freezes the certainty a granted patent normally carries. Licensing terms that assumed a stable right become harder to negotiate, because the licensee's counsel will usually flag the open opposition as a live risk. Any infringement claim based on the patent runs alongside the possibility that the claim itself disappears before it is resolved. The patentee cannot treat the grant as final until the opposition division has ruled and the appeal period, if used, has passed without a further challenge.
Where opposition evidence includes personal correspondence or inventor records, the exchange between the parties should still follow ordinary data handling terms. See Data processing agreement explained for how such exchanges between counsel and a client are usually documented before they leave the file.
What to do to start and run the file
- Confirm you are within the period the granting office sets for filing opposition; this period is stated in the notice of grant and is not extended informally by request.
- Draft the statement of grounds. Each objection needs its own legal basis and its own supporting document — a mixed, undifferentiated statement is the most common cause of a partial rejection at the formal check.
- Collect prior art, expert statements and any other evidence before the file closes. The logic used to weigh such material elsewhere is comparable — see Evidence standards in ownership of results in practice for how assessors treat documentary proof.
- File the opposition together with the required fee receipt; an opposition lodged without proof of payment is treated by most offices as not filed at all.
- Track the office's communications closely. Each round in the written exchange sets its own response window, and a file can close on a missed deadline even where the substantive argument is strong.
- Instruct a single representative where the dispute touches more than one jurisdiction, so that submissions stay consistent across the file and translations do not drift in meaning between rounds.
Who decides, and on what timeline
The opposition division of the granting office decides in first instance. It examines each ground raised, may invite further written submissions from either side, and can call oral proceedings to clarify disputed points before it decides. The office does not commit to a fixed calendar for any of these steps. The file moves at a pace set by the number of grounds, the volume of evidence submitted, and whether a hearing is scheduled at all.
A party that loses in first instance can challenge the decision before a higher board within the office's own appeal structure. That board reviews the case on the merits and not only on procedure, so a weak first-instance record is difficult to repair once the file reaches appeal. Parallel national proceedings on the same patent, where they exist, typically wait for the opposition outcome rather than run ahead of it.
| Stage | What happens | Who acts |
|---|---|---|
| Filing | Opponent lodges the statement of grounds and evidence within the set period | Opponent |
| Formal check | Office verifies fee payment and formal admissibility of the filing | Office |
| Written exchange | Patentee replies to the grounds; opponent may comment further | Patentee, opponent |
| Oral proceedings | Office may hold a hearing to clarify disputed points before deciding | Office, both parties |
| Decision | Office maintains, amends or revokes the patent | Office |
| Appeal | Losing party may challenge the decision before a higher board | Losing party |
Common forks
If the other side files nothing within the response window it was given, the office still examines the merits of the opposition itself. It does not treat silence as an admission, but it also does not wait indefinitely for a reply that never arrives.
If the opposition raises several independent grounds, the office may accept some and reject others. The patent can then survive in an amended, narrower form rather than being revoked outright, which changes what the patentee can later enforce.
If the patentee amends the claims during the proceeding, the opposition division re-examines only the amended scope. Grounds aimed squarely at the original wording can become moot without a separate ruling on them.
What this page does not solve
This page describes the stages and the decision-making structure of opposition. It does not predict whether a specific set of grounds will succeed on its facts, and it does not quantify fees, translation costs or representative charges, since none of those figures are stable enough across offices to state here. It also does not cover a later revocation action once the opposition period itself has closed; that route starts from a different point and answers a different question about the same patent.
Sources and limit
The description above follows the general structure of opposition procedures as published by granting offices. It does not cite a specific national or supranational act, because no single act applies uniformly across the jurisdictions this page is written to cover, and a procedure page should not borrow a citation from a file it was not written for.
Where the dispute also requires establishing who actually stands behind an opposing party — a licensee, a shell entity, a successor in title — that check sits outside this page entirely. It is a registry-based report, not a legal opinion: see Counterparty in Switzerland in detail for what such a file can and cannot establish before you rely on it.
Checked: this description reflects publicly available procedural guidance current at the time of writing. A specific filing should still be checked against the granting office's own current notice before any date on it is treated as final.
Related publication
A patent that survives opposition, or was never opposed at all, can still face a separate challenge later in its life. See Revocation proceedings step by step for how that later route is structured and where it differs from opposition.
FAQ
How long does opposition before the granting office take in practice?
The office does not set a fixed calendar for the whole procedure. Duration depends on the number of grounds raised, the volume of evidence exchanged between the parties, whether oral proceedings are scheduled, and whether either side appeals the eventual decision.
Which documents are needed to start?
A statement of grounds tied to specific, identified evidence, proof of the required fee payment, and a power of attorney where a representative files on the opponent's behalf. Prior art documents and expert statements are added as supporting evidence, not as separate filings in their own right.
What happens if the other side does not respond?
The office still examines the merits of the opposition on its own. Silence from the patentee is not treated as agreement with the grounds raised, but it also removes the patentee's chance to rebut them before the decision is written.
Next step
If the opposition fails and the patent stands, the practical risk shifts from filing an opposition to defending against enforcement of the right you tried to remove. See When enforcement is sought against a holder explained for the first moves once that risk becomes concrete. For a specific file, send the notice of grant and the grounds you are weighing; a first reaction follows within the working day.