Can I reuse a patentability search as an invalidity search?

No. A patentability search was run against your own disclosure, usually broadly, to predict what an examiner would cite. An invalidity search is run against the specific claims of an issued patent, limited to art before its priority date, and has to map each claim limitation to a citation. The references may overlap; the work product does not.

What is the difference between an invalidity search and a validity search?

The same search, commissioned by opposite sides. A validity search is run by or for the patent owner, typically before assertion or a transaction, to find out what a defendant will find. An invalidity search is run by or for the accused party. The method and the deliverable are identical; only who is hoping for a negative result differs.

Does a freedom-to-operate search look at prior art?

Not primarily. FTO searches in-force, unexpired patents and pending applications in the jurisdictions where you will make, sell or import, and reads their claims against your product. Prior art enters only afterwards: if a blocking patent is found, an invalidity search is the usual next step to clear it.

What does a landscape or state-of-the-art search do?

It maps who holds what in a technology area — filing trends, top assignees, the classification clusters — without reference to a specific claim. It is a strategy document, not a legal opinion, and it is the wrong instrument for any question that begins with a claim.

Guides

Types of patent searches: invalidity vs. patentability vs. freedom-to-operate

Michael W. Smith, former USPTO patent examiner · September 13, 2026

A patentability search asks whether your invention is new, before you file. An invalidity search asks whether someone else's issued patent should never have been granted, and searches only art dated before that patent's priority date. A freedom-to-operate search asks whether your product infringes anyone's in-force claims, and searches live patents rather than prior art. They search different dates, different documents and different claims, so one cannot substitute for another.

The four searches, side by side

Search	Question	Date window	What is read against what
Patentability (novelty)	Is my invention new and non-obvious?	Everything before your filing date	Your disclosure, as broadly as it might be claimed, against all published art
Invalidity (or validity)	Should this issued patent have been granted?	Only before the patent's priority date	The patent's specific claims, limitation by limitation, against art the examiner did not apply
Freedom-to-operate (clearance)	Does my product infringe anyone's live claims?	In-force patents and pending applications, now	Your product's features against the claims of others' unexpired patents
Landscape (state of the art)	Who owns what in this field?	Usually the last 10–20 years	A technology area against the whole filing record, statistically

Why the date window changes everything

A patentability search has no lower bound and a soft upper bound: anything published before you file counts, and most of it will not matter. An invalidity search has a hard upper bound — the target's earliest supported priority date — and a reference one day after it is worthless no matter how perfectly it reads on the claims. That single constraint reshapes the whole search: the first task is to establish what the priority date actually is, including whether the claims are supported by the provisional the patent claims priority to, because a broken chain moves the date forward and brings years of art into play.

Freedom-to-operate inverts the window. What matters is what is alive: unexpired patents, published applications that could issue, and their claims as they stand today, including any narrowing during prosecution. Expired art is irrelevant to FTO except as a defense once a blocking patent turns up.

Why the claims change the method

A patentability search is run against an invention that has not been claimed yet, so the searcher works from the disclosure and tries to anticipate the broadest claim an examiner would face. It is a wide, shallow search by design.

An invalidity search is run against claims that already exist and cannot change. Every limitation of every asserted claim is a target, and the search is only done when each limitation has either a citation or a documented reason it could not be found. This is why the deliverable is a claim chart rather than a list: a reference that shows nine of ten limitations is not a partial success, it is a §103 secondary reference waiting for a primary. The examiner's own search record is read first, because the art that invalidates is usually in the field the examiner searched and one classification away from where they stopped.

FTO reads the other way around: your product is fixed, and the question is which of thousands of live claims it could fall inside. It is a claims-first search of a different population of documents, and it is the one of the four that most needs a legal opinion attached to it.

Which one you actually need

Before filing an application — patentability. It shapes the claims you draft and the arguments you will face. A pre-filing search at a fixed fee is on the office-action page.
After being sued, or on receiving a demand letter — invalidity, of the asserted claims. Start with the independent claims; if they fall, the dependents usually follow.
Before filing an IPR petition — invalidity, but limited to patents and printed publications, and measured against the prosecution record for §325(d) exposure. See how much prior art an IPR petition needs.
Before launching a product or entering a market — freedom-to-operate, jurisdiction by jurisdiction.
Before acquiring or licensing a portfolio — validity of the key patents, and a landscape of the field they sit in.
Before choosing an R&D direction — landscape.

What they have in common

All four fail the same way: a keyword search finds art that uses your vocabulary, and the art that matters usually uses someone else's. The remedy is the same too — classification-anchored search, seeded from the closest art actually found, extended into foreign families and non-patent literature. That is the method behind every search here, and it is described on the invalidity page because invalidity is where it earns its keep.