Claim construction: what the other side does
Once infringement or validity is disputed, the wording of the claim itself becomes a battleground. The other side does not simply deny infringement — it files its own reading of the disputed terms, backs that reading with expert opinion and prior art, and uses the schedule to push the case toward validity rather than infringement. None of this is binding until the forum rules on construction.
How the phase runs
Claim construction is a defined stage inside a wider infringement or revocation dispute. It does not happen in isolation: the forum sets a timetable, both sides submit written positions on what each disputed term means, and a technical hearing usually follows before any ruling on infringement is even discussed.
The other side's filing typically does three things at once. It proposes a narrower reading of the term that covers your product, so that infringement becomes harder to establish. It proposes a broader reading of the same term elsewhere, so that prior art appears to anticipate it. And it attaches an expert declaration that supports both readings under a single technical theory.
This is not contradictory from their side of the table — it is the standard shape of a defence built around claim scope. Recognising the pattern early changes how you respond, and how much of your own budget goes into rebuttal rather than into the infringement case itself.
| Stage | What the other side typically files | Typical window |
|---|---|---|
| Initial response | Counter-statement disputing the claimant's proposed construction | Weeks after the claimant's own construction brief |
| Expert submission | Technical declaration supporting a narrower or broader reading | Set by the forum's procedural order |
| Prior art cross-reference | Documents chosen to match the broader reading of the term | Filed alongside or shortly after the expert submission |
| Construction hearing | Oral argument before the panel or judge | After written submissions close |
| Ruling on construction | — | Sets the scope for the remainder of the dispute |
What this changes in practice
Once the forum rules on construction, the scope of the dispute is largely fixed. Infringement and validity arguments that relied on a different reading of the term lose their footing. This is the point of no return in the timeline: revisiting it later is expensive and rarely succeeds.
Delay at this stage is also a tactic in itself. A wide construction dispute keeps the case in a preliminary phase, postpones disclosure obligations, and gives the other side more time to prepare a validity attack. Treat the schedule itself as part of the substance, not as an administrative detail.
What to do
- Fix your own proposed construction in writing before the other side files theirs, and keep it internally consistent with your infringement theory.
- Instruct a technical expert early enough to respond to the other side's declaration within the forum's deadline, not after it.
- Cross-check any prior art cited against the broader reading the other side is proposing — the mismatch is often where their case is weakest.
- Log every date in the procedural order and flag the construction hearing to your team as a fixed point, not a placeholder.
- Prepare a fallback construction for each disputed term, so a partial loss on wording does not collapse the whole infringement case.
- Keep a written record of which submissions responded to which filing — this matters if the ruling is appealed.
Who decides
The ruling on claim construction comes from the panel or judge seized of the infringement and validity dispute, not from either party's expert. Where a European patent has been validated in several countries, this can run before a national court or, for patents within its jurisdiction, before the Unified Patent Court. The forum's own procedural order — not general practice — sets the actual deadlines for each filing.
Where this splits into different cases
If the patent's ownership itself is contested alongside infringement, construction is usually paused until ownership is resolved, because an entity without standing cannot argue claim scope. When a development partner claims joint ownership explained sets out how that question is handled separately.
If a licence or royalty stream depends on the same patent, a construction ruling can change what counts as licensed use going forward. Royalty enforcement step by step explained covers what to prepare once scope is fixed.
If the other side files a parallel revocation action rather than a defence on infringement alone, expect the construction brief to lean almost entirely on the broader reading — revocation strategy and infringement defence pull the same term in opposite directions.
Sources and limits
This page describes the mechanics of the construction phase: what gets filed, in what order, and what the ruling fixes for the rest of the case. It does not set out timing or fee figures for a specific file, because those depend on how many validations, forums and prior filings are already in play. Where a dispute needs a first read of the counterparty's own filing history before construction starts, Counterparty report when the counterparty changes name in detail shows how that check is run.
Verified
Reviewed for procedural accuracy against current forum practice. Collection, cross-checking and dating of the underlying material follow the process set out in Methodology: collection, cross-checking and dating explained.
Related reading
Evidence gathering in two countries step by step covers the parallel stage where the same tactical patterns appear in disclosure rather than in claim wording.
Next steps
If a family opt-out deadline is approaching while construction is still open, see The opt-out window is closing on a family patent.
If the dispute involves a supplier accused of infringing a third party's patent rather than your own, see A supplier is accused of infringing a third party.
If a licence tied to the patent is at risk because of a counterparty's insolvency, see When a licence survives insolvency, or does not explained.
FAQ
How long does the construction phase usually take?
It runs from the first construction brief to the forum's ruling, and the length depends entirely on the procedural order set by the panel or judge. Complex, multi-term disputes with expert evidence on both sides run longer than single-term disagreements.
Which documents does the claimant need to start this phase?
A proposed construction for each disputed term, the patent specification and file history, and — where relied on — a technical expert declaration supporting that reading. Prior art you intend to distinguish should be ready before the other side files theirs.
What happens if the other side does not respond to a construction filing?
A non-response does not resolve the dispute in the claimant's favour automatically. The forum still rules on construction based on the material before it, and a missed deadline can be treated as a procedural default with its own consequences under the forum's own rules.