Patent Priority Date

The priority date is the date used to measure the patentability of an invention and determine who prevails when two applicants claim the same invention: DEFINITION: the priority date (also called the effective filing date) is the date from which prior art is measured — any publication, patent, use, or sale BEFORE the priority date can be used to reject the application; anything occurring AFTER the priority date generally cannot be used as prior art; AIA FIRST-INVENTOR-TO-FILE (effective March 16, 2013): under the America Invents Act, the US shifted to a first-inventor-to-file system; priority generally belongs to the first applicant to file; if two inventors independently conceive the same invention, the one who files first gets the patent (with limited exceptions for derived applications where one party stole the idea from the other); PRE-AIA FIRST-TO-INVENT (before March 16, 2013): for patents with effective filing dates before March 16, 2013, priority can be established based on the date of invention (conception + reduction to practice); this system is now limited to legacy applications; TYPES OF PRIORITY DATE: (a) ACTUAL FILING DATE: the date the patent application is physically filed at the USPTO; (b) PROVISIONAL PRIORITY DATE: the filing date of an earlier provisional application whose benefit is claimed — up to 12 months earlier; (c) FOREIGN PRIORITY DATE (PARIS CONVENTION): the filing date of an earlier patent application in a Paris Convention member country — up to 12 months earlier; (d) PCT APPLICATION DATE: the filing date of a PCT application for which US national phase is entered — up to 30 months earlier for the national phase entry; PRACTICAL IMPACT: an earlier priority date: (a) gives the applicant the ability to overcome more prior art; (b) prevents a competitor's intervening publication from being used against the application; (c) determines whose patent issues when two competitors race to file.

A provisional application establishes an effective priority date up to 12 months before the nonprovisional filing date: MECHANISM: a nonprovisional application (or PCT application) filed within 12 months of the provisional can claim the benefit of the provisional's filing date; 35 U.S.C. § 119(e): the nonprovisional must claim this benefit explicitly in its opening 'This application claims the benefit of...' paragraph; WHAT IS COVERED BY THE PROVISIONAL'S DATE: ONLY the subject matter disclosed in the provisional gets the provisional's priority date; new subject matter added in the nonprovisional (but not in the provisional) gets only the nonprovisional's filing date; THIS IS CRITICAL: a thin or incomplete provisional can silently give away priority for key innovations added later; example: provisional filed January 1, 2024, discloses embodiment A; nonprovisional filed January 1, 2025, adds embodiment B; if a competitor publishes embodiment B on June 1, 2024, embodiment B claims in the nonprovisional may be rejected over that publication — the provisional didn't cover embodiment B, so the priority date for B is January 1, 2025 (too late); WRITTEN DESCRIPTION REQUIREMENT: the provisional must provide written description support for any claim in the nonprovisional that seeks to benefit from the provisional's date; Fiers v. Revel (Fed. Cir. 1993) and related cases: the provisional must describe the invention with sufficient detail to establish possession at the time of filing; MULTIPLE PROVISIONALS: a nonprovisional can claim the benefit of multiple provisionals filed within the 12-month period; different claims can claim priority to different provisionals; this enables a 'rolling provisional' strategy where each new development is locked in as it occurs.

The Paris Convention allows patent applicants to claim the priority date of an earlier foreign application when filing in other member countries: PARIS CONVENTION BASICS: the Paris Convention for the Protection of Industrial Property (1883) provides that an application filed in a member country within 12 months of an earlier application in another member country can claim the earlier application's filing date as its priority date; virtually all commercially significant countries are Paris Convention members; MECHANISM: an inventor files a patent application in Country A (e.g., US provisional or US nonprovisional) on January 1, 2024; the inventor files corresponding applications in Country B (e.g., Germany) by January 1, 2025; the Country B application claims priority to the Country A application; Country B examines the application against prior art as of January 1, 2024 (not the January 2025 filing date); WHAT CLAIMING PARIS CONVENTION PRIORITY REQUIRES: (a) the later application must be filed within 12 months of the priority application; (b) the later application must claim priority in writing, identifying the earlier application (country, filing date, application number); (c) the later application must include a certified copy of the priority document from the original country; PCT INTERSECTION: a PCT application filed within 12 months of the priority date (US provisional or nonprovisional) preserves Paris Convention priority for all PCT member countries; national phase entries filed up to 30 months from the priority date can still claim the original 12-month priority; WHAT IS NOT COVERED: subject matter in the foreign application that was not in the priority document does not get the priority date; FOREIGN LANGUAGE PROVISIONALS: a provisional filed in a foreign language can establish a priority date for a subsequent US nonprovisional, provided the provisional provides written description support in that language; a translation must eventually be filed.

In patent prosecution and litigation, the priority date is frequently challenged — understanding how to defend it is essential: OFFICE ACTION PRIOR ART REJECTIONS: an examiner may cite a prior art reference with a publication date that appears to precede the application's filing date; the applicant can respond by: (a) CORRECTING THE EXAMINER: pointing out that the application's priority date predates the reference's effective date; (b) SWEARING BEHIND (PRE-AIA ONLY): for applications with effective filing dates before March 16, 2013, an applicant can swear behind a reference by submitting a 37 C.F.R. § 1.131 declaration showing that the invention was conceived and reduced to practice before the reference's date; AIA DERIVATION PROCEEDING: under the AIA, if an inventor believes a competing application derived its invention from the inventor (i.e., the competing applicant stole the idea), the inventor can file a derivation proceeding at the PTAB; the petitioner must show: (a) the invention was communicated to the respondent; (b) the respondent's disclosure is the same or substantially the same as the communicated subject matter; the 12-month deadline for filing derivation petitions runs from the first publication of a claim that covers the derived invention; AIA § 102(b)(1) GRACE PERIOD: an inventor's own disclosures within 1 year of the effective filing date are NOT prior art; even if the inventor published their own work 6 months before filing, that publication cannot be used to reject the inventor's patent application; but it CAN destroy foreign patent rights in absolute-novelty countries (no grace period); COMMON-OWNERSHIP EXCEPTION (§ 102(b)(2)): if the prior art reference is also owned by the same entity as the application (e.g., an earlier filing by the same company), the AIA § 102(a)(2) prior art effect can be overcome by a joint research agreement or prior invention statement.

Continuation and continuation-in-part applications have complex effective filing date structures that affect their patentability and claim scope: CONTINUATION APPLICATIONS: a continuation application claims the benefit of the parent application's filing date under § 120; ALL claims in the continuation must be supported by the parent application's original disclosure; if the continuation adds no new matter (same specification + drawings, new claims only), all claims get the parent's priority date; CONTINUATION-IN-PART (CIP) APPLICATIONS: a CIP adds new subject matter (new content not in the parent application); the CIP's claims have a SPLIT effective filing date: claims that are fully supported by the parent application's disclosure → parent's priority date; claims that require the new subject matter added in the CIP → CIP's actual filing date (NOT the parent's date); THIS IS FREQUENTLY MISSED: a patent owner may believe all CIP claims get the parent's early priority date, but claims directed to new features added in the CIP get only the CIP's date; the new features may be anticipated or obvious over prior art published between the parent's date and the CIP's date; EXAMPLE: parent application filed January 1, 2020 discloses method A; CIP filed January 1, 2022 adds method B (new embodiment); competitor publishes method B on June 1, 2021; claims in the CIP directed to method B get the CIP's January 1, 2022 filing date → the competitor's June 2021 publication may anticipate those claims; WRITTEN DESCRIPTION TEST: to get the parent's priority date, the claim must find written description support in the parent application; the test is whether the parent application's specification demonstrates that the inventor possessed the claimed subject matter as of the parent's filing date.