Opposition Search for SEPs
An opposition search, also called a nullity search, hunts for prior art that can defeat the claims of a patent that has already been granted. It runs against all the claims and draws on patent and non-patent sources.
Two searches, two points in the patent's life
A novelty search and an opposition search ask the same underlying question — does the art hold up? — but at opposite ends of the process, and the standard of proof differs accordingly.
Novelty search — checks an invention disclosure against everything published, to decide what's worth claiming.
Opposition search — checks a granted patent's claims against everything published before its priority date, to see if they can be defeated.
What the work involves
- Comprehensive reports that challenge the granted claims, built around prior art that reads on the specific claim language.
- Analysis of the prosecution history, to identify the basis on which the patent was allowed and where an attack has to land.
- Research across patent databases, non-patent literature and journals, to find disclosures an examiner may never have seen.
Which sources are searched
Patent documents are the fast route to a close reference. Non-patent sources are slower to search but often hold what a patent examiner never saw.
Patent documents
Give clean priority dates and claim-style language, making them the quickest route to a close reference.
Non-patent literature
Conference papers, technical journals, standards contributions, product manuals and theses — sources that often hold the disclosure an examiner never saw.
The prosecution history of the target patent is reviewed alongside both, since it narrows where to look and shows what an attack has to overcome.
When to run one
Timing is not a formality here — it decides which options are still open.
Start as soon as a competitor patent of concern is granted.
Formal opposition windows at many offices close a fixed period after grant, and the slower part of the work — non-patent literature and the prosecution history — needs the time.
The claims were granted once. That's not the same as surviving a second look.
Who commissions it
Companies monitoring competitors
Watching competitor patenting activity, which is usually what surfaces a patent worth challenging in the first place.
In-house counsel
Have spotted a recently granted patent that blocks a product or a plan already underway.
Law firms
Preparing an opposition or a revocation action and needing the search and report to build it on.
What you receive
- A comprehensive report setting out prior art that challenges the granted claims
- A nullity analysis covering all claims of the target patent
- An analysis of the prosecution history identifying the basis for the allowance
- Research results drawn from patent databases, non-patent literature and journals
Frequently asked questions
What is an opposition search?
A prior art search aimed at knocking down a patent that has already been granted. It runs across all the claims and looks for disclosures published before the priority date. Findings go into a comprehensive report that challenges the granted claims, supported by an analysis of the prosecution history showing the basis on which the patent was allowed.
How does this differ from a novelty search?
A novelty search looks at an invention before filing and asks whether it's new. An opposition search looks at a patent after grant and asks whether its claims can be defeated. The evidence standard differs too: an opposition needs art that reads on specific granted claim language, carries a reliable date before the priority date, and is documented well enough to survive challenge.
Which sources are searched?
Patent databases, non-patent literature, and journals. Patent documents give clean dates and claim language, so they're the fastest route to a close reference. Non-patent sources — conference papers, technical journals, standards contributions, product manuals, theses — often hold the disclosure an examiner never saw. The prosecution history of the target patent is reviewed alongside the search.
When should an opposition search be run?
As soon as a competitor patent of concern is granted. Moving early keeps the widest set of options open, since formal opposition windows at many offices close a fixed period after grant. An early start also leaves time for the slower part of the work — the non-patent literature and the prosecution history review.
Get the target patent searched
Tell us which granted patent is of concern and how it's affecting you, and we'll scope the nullity search.
