Under 35 U.S.C. 120, a later U.S. patent application can claim priority to an earlier U.S. application, and inherit its filing date for prior art purposes, if four things are true: the two applications share at least one inventor, the earlier application’s disclosure fully supports the later claims, the later application contains a specific reference to the earlier one, and the later application is filed while the earlier one is still pending.1Office of the Law Revision Counsel. 35 USC 120 – Benefit of Earlier Filing Date in the United States Getting that earlier date can decide whether an intervening publication counts against your claims. It also starts the 20-year patent term clock running from the earlier filing, which is the part applicants most often forget to weigh.
The Four Requirements
Section 120 works only when every requirement is met. Losing any one of them drops the later application back to its own actual filing date, and any prior art from the intervening period becomes fair game.
At Least One Common Inventor
The later application must name at least one inventor who was also named in the earlier one. The lists don’t need to match exactly; they need to overlap. If inventorship needs correcting after filing, the USPTO handles that through a request under 37 C.F.R. 1.48, with an updated application data sheet and a processing fee.2United States Patent and Trademark Office. 2109 Inventorship3eCFR. 37 CFR 1.48 – Correction of Inventorship Pursuant to 35 USC 116
Adequate Written Description in the Earlier Filing
Each claim in the later application must find support in the earlier application’s disclosure. Under 35 U.S.C. 112(a), that disclosure must describe the invention well enough that a person skilled in the field could make and use it.4Office of the Law Revision Counsel. 35 USC 112 – Specification Any claim element that wasn’t described in the earlier filing gets only the later application’s actual filing date, even if the rest of the claims properly claim priority. The Federal Circuit examined this in PowerOasis, Inc. v. T-Mobile USA, Inc., holding that certain claims lacked adequate support in the earlier filing and were therefore not entitled to the earlier priority date. Priority is analyzed claim by claim, not application by application.
A Specific Reference to the Earlier Application
The later application must identify the earlier filing by application number and filing date, either in the specification itself or in an application data sheet. This is where practitioners most often trip. In Medtronic CoreValve LLC v. Edwards Lifesciences Corp., the Federal Circuit affirmed that a patent was invalid because intermediate applications in the priority chain failed to properly reference earlier filings, pushing the effective priority date years later and exposing the claims to anticipating prior art.5Justia. Medtronic CoreValve LLC v Edwards Lifesciences Corp, No 13-1117 (Fed Cir 2014) And in Droplets, Inc. v. E*Trade Bank, the Federal Circuit held that incorporating an earlier application by reference did not satisfy the statutory requirement for a specific reference, and the resulting gap in the chain invalidated the claims.6FindLaw Caselaw. Droplets Inc v E*Trade Bank, 16-2504 General incorporation-by-reference language will not do the job. The reference must explicitly identify the prior application.
Copendency
The later application must be filed before the earlier one is patented, abandoned, or otherwise terminated.1Office of the Law Revision Counsel. 35 USC 120 – Benefit of Earlier Filing Date in the United States Three events end copendency:
- The parent issues as a patent. You can file the continuing application on the same day the patent issues, but not after. The Federal Circuit confirmed the same-day rule in Immersion Corp. v. HTC Corp.7United States Patent and Trademark Office. Claiming the Benefit of an Earlier Filing Date Under 35 USC 120 and 119(e)
- The parent is abandoned, whether through failure to respond to an office action, express abandonment, or failure to pay the issue fee.
- Proceedings otherwise terminate.
Because a patent issues shortly after the issue fee is paid, the safe practice is to file any continuing application before paying that fee on the parent, not after.
Deadline for Submitting the Priority Claim
Filing the continuing application on time is only half of it. The specific reference to the earlier application also has its own deadline. Under 37 C.F.R. 1.78(d)(3), the reference must be submitted during the later application’s pendency and no later than the later of four months from the actual filing date of the later application, or sixteen months from the filing date of the prior application.8eCFR. 37 CFR 1.78 – Claiming Benefit of Earlier Filing Date and Cross-References to Other Applications
Missing this window doesn’t automatically destroy the priority claim, but recovering is expensive. The USPTO accepts petitions for unintentionally delayed benefit claims under 37 C.F.R. 1.78(e). If you petition within two years of the deadline, the fee is $2,260 for a large entity, $904 for a small entity, or $452 for a micro entity. After two years, it climbs to $3,000, $1,200, or $600 respectively.9eCFR. 37 CFR 1.17 – Patent Application and Reexamination Processing Fees You also have to show the delay was unintentional. Forgetting is not the same thing.
Chains Across Multiple Applications
When priority runs through more than one application, say a parent, a first continuation, and a second continuation, every link has to satisfy Section 120 independently. The second continuation doesn’t need to reference the original parent directly, but the first continuation must properly claim priority to the parent, and the second must properly claim priority to the first. If any link breaks, every application downstream from the break loses the earlier date. Medtronic CoreValve and Droplets both turned on broken chains, and both patents lost claims as a result.
If an examiner challenges the priority claim during prosecution, you’ll need to show that each application was copending with its predecessor, that each contained the required specific reference, and that the original disclosure supports the claims being asserted. That last piece surfaces most often in continuations-in-part, where the line between original and newly added disclosure can blur.
Which Applications This Applies To
Section 120 priority runs through three kinds of continuing applications, all subject to the same requirements above.10United States Patent and Trademark Office. 201 Types of Applications
A continuation pursues different claims from the same disclosure as the parent. No new subject matter is allowed, so every claim gets the parent’s filing date.
A divisional is filed after an examiner issues a restriction requirement under 37 C.F.R. 1.142, forcing the applicant to elect one invention from several disclosed.11eCFR. 37 CFR 1.142 – Requirement for Restriction Each non-elected invention can be pursued in a divisional that retains the parent’s filing date. Divisionals also get a safe harbor under 35 U.S.C. 121: a patent issued on a properly filed divisional cannot be used as a prior art reference against the original application or against other divisionals from the same restriction, as long as the claims stay within the boundaries the examiner drew.
A continuation-in-part (CIP) adds new disclosure beyond the parent. Claims that rely only on material from the parent keep the earlier priority date. Claims that depend on the new material get only the CIP’s actual filing date. Because the analysis runs claim by claim, applicants sometimes lose priority for claims they assumed were covered.
The Patent Term Tradeoff
Claiming the benefit of an earlier filing date shortens the patent’s effective life. Under 35 U.S.C. 154(a)(2), a utility patent expires 20 years from the filing date of the earliest application in the priority chain to which benefit is claimed under Section 120.12United States Patent and Trademark Office. Patent Term A continuation that claims priority to a parent filed five years ago is running against a clock that has already burned five of its 20 years.
Two categories of priority do not start that clock. Foreign priority claims under 35 U.S.C. 119(a) through (d) are ignored for patent term. So are claims to the benefit of a provisional application under 35 U.S.C. 119(e).12United States Patent and Trademark Office. Patent Term That distinction is why provisionals are often used as a first filing: they preserve a priority date without eating into term. A long chain of Section 120 continuations, by contrast, can leave an issued patent with only a few years of enforceable life.
Section 120 Is Not Foreign Priority
Section 120 governs priority based on an earlier U.S. application. Priority based on a foreign application runs through a different statute, 35 U.S.C. 119, which requires filing the U.S. application within 12 months of the earliest foreign filing (with a possible two-month extension for unintentional delays) and providing the foreign application number, country, and filing date.13Office of the Law Revision Counsel. 35 USC 119 – Benefit of Earlier Filing Date; Right of Priority The requirements, deadlines, and term consequences are different, so a filing strategy that mixes domestic and foreign priority needs to treat the two statutes separately.