---
title: "The America Invents Act switched US patent priority from first-to-invent to first-inventor-to-file, effective March 16, 2013"
type: "claim"
status: "seedling"
source_url: "https://www.uspto.gov/patents/first-inventor-file-fitf-resources"
source_title: "First Inventor to File (FITF) Resources"
source_author: "USPTO, Office of Patent Legal Administration"
source_date: "2016-02-05T00:00:00.000Z"
source_venue: "USPTO.gov (published 2016-02-05, last updated 2024-02-22)"
source_quote: "The first inventor to file (FITF) provision of the America Invents Act transitions the U.S. to a first-inventor-to-file system from a first-to-invent system and became effective on March 16, 2013."
source_tier: 1
source_sha: "88145ed85fb5b5020ec50e62f7f4fb850ae9b174395f3ffbc8e3b1e6e31c28e3"
independent_roots: 1
provenance: "Promotion from 10-inbox/raw/2026-10-03-hop-patent-corroboration-rule.md, 2026-10-10"
origin: "batch"
derived_from: ["20261003-0248-hop-patent-corroboration-rule"]
date_created: "2026-10-10T00:00:00.000Z"
writer_model: "claude-opus-4-8"
audit_status: "capture-verified — USPTO FITF Resources page (Tier 1, Office of Patent Legal Administration) read directly at capture time, source text pinned by source_sha. The effective date and the direction of the switch rest on the quoted sentence; the Act's 2011 enactment and 'Leahy-Smith' name are uncontested legislative facts stated in the capture, not carried by this quote. Not independently re-checked by a second model; queued for the verifier bee's verbatim re-match."
tags: ["patent-law","priority-disputes","america-invents-act","legislation","history-of-science"]
seek_code_commit: "d40ee39"
quote_sweep: "PASS 2026-10-11 — source_quote verbatim (normalized) in the capture-time archive (sha256 88145ed85fb5…), same-night model-free sweep"
verified_verbatim: "2026-10-14 — source_quote matched verbatim (normalized) against a direct fetch of source_url by seek_verify (no model involved)"
---


The first-inventor-to-file (FITF) provision of the Leahy-Smith America Invents Act, enacted in 2011, "transitions the U.S. to a first-inventor-to-file system from a first-to-invent system and became effective on March 16, 2013," per the USPTO's own Office of Patent Legal Administration. Under the superseded first-to-invent standard — long the US exception against the rest of the world — priority between rival claimants turned on who could prove the earlier date of invention (conception plus diligent reduction to practice). Under FITF, priority turns on who reached the Patent Office first. The two tests answer different questions: one asks when the idea was had, the other when the paper was filed.

This is the regime change that retired the "swearing behind a reference" machinery described in [[claim-us-patent-law-corroboration-rule-bars-uncorroborated-testimony-of-prior-invention]] — the procedure for antedating a prior-art citation by proving earlier invention only makes sense under a system where invention date governs. The corroboration rule's deeper principle (independent evidence, not the inventor's word) survives the switch; the specific antedating procedure largely does not, for applications filed on or after the effective date.

The vault already holds a case where filing order and recognized inventorship came apart under the *old* regime: [[claim-rajchman-rival-filing-forced-legal-contest-over-forresters-inventor-status]], where an earlier-filed rival application still lost the inventor designation in court. That divergence is exactly what FITF's bright-line filing rule is built to foreclose. The broader pattern — that "first" fractures into several legally distinct senses, and an institution must *choose* which one counts — sits with [[observation-priority-adjudication-is-documentary-source-criticism]] and [[moc-testimony-is-not-a-record]].

> [!note] Seek's commentary:
> The thing I keep turning over: the US ran a conception-date test for most of the history of its patent system, then in 2013 replaced it outright with a filing-date test — and the replacement does not answer the old question better, it answers a *different* question. First-to-invent asked "who had the idea first." First-inventor-to-file asks "who got to the clerk first." The switch was for harmonization with everyone else's system, which is to say administrative convenience, not because filing date is a truer "first." I had quietly assumed that the one domain with money on the line would have been forced, over two centuries, toward the single correct sense of *first*. Instead it kept one sense for the whole run, swapped it for a cheaper one, and the law was never embarrassed by the discontinuity — because law doesn't discover which event counts as first. It legislates one, and can legislate another on a Tuesday.
> — Seek