Key Takeaways

  • The priority date in a patent is crucial because it determines what counts as prior art against the invention.
  • Priority dates can be claimed from provisional, non-provisional, or foreign applications.
  • Missing deadlines for claiming priority (e.g., failing to convert a provisional application) risks losing the original priority date.
  • Priority dates affect international filings; deadlines for foreign filings often depend on the priority date.
  • Multiple priority dates can exist for different invention features if filed in separate applications over time.

A priority date patent establishes the priority date as the earliest date an application may claim precedence. It also defines what materials are prior art to the patent. This is why it's important to obtain the earliest possible priority date as it can play a key role in the patentability of particular inventions.

In a situation with only one patent application, the priority date is the same as the filing date for the single application. When there are multiple related patent applications, the application's priority date is the filing date of the earliest patent that initially disclosed the invention.

It's known as the priority application, and the earliest patent filing can be one of three types:

This term can also reference the earliest filing date for a specific aspect of your invention. This means it's conceivable to have various priority dates if the applicant added new features in related patent applications.

What is a Patent Filing Date?

The patent filing date is when the United States Patent Office recognizes the application for your patent was filed. It's a key date as it establishes who has priority, or which application should get the patent first. If you have two parties who've filed patent applications at the same time on a similar invention, the one who filed first has priority. There are situations where the filing date on your patent application is different than whatever date you filed the application, which results in the distinction between the effective filing date and the actual filing date.

What is the Actual Filing Date?

When you hear the term actual filing date, this is the date that someone physically submitted, or filed, the application with the United States Patent Office. All filing dates are very significant in patent law because these dates can establish who the first inventor was and who should be the first to be entitled to a patent. Filing dates can also determine how long the patents rights are good for. If your application for a non-provisional patent is approved, you're given patent rights for 20 years, which start running on your actual filing date.

What is the Effective Filing Date?

An application can “inherit” another application's previous filing date to determine the effective filing date. If you file for a provisional patent application, it means you're preserving the filing date before you opt to start the full and more expensive process of a non-provisional application.

For example, you file the provisional patent application on February 1, 2019, and then file the non-provisional one December 1, 2019. The actual filing date would be December 1, 2019, but the effective filing date would be February 1, 2019. In the event someone files an application between these dates, the provisional application would still take priority over the other person's application and be the first one entitled to a patent. This is what it means when your application inherits the provisional application's filing date. As far as the Patent Office is concerned, your application is ahead of the other person's application even though you didn't file the non-provisional patent application earlier than they did. The provisional application essentially saves the date to be utilized by the non-provisional application later on.

Why Priority Dates Matter

The priority date patent is not merely a technical filing detail; it plays a central role in securing patent rights. The priority date determines whether other patent filings or publicly available documents qualify as prior art against your application. Any disclosures made before the priority date can invalidate a patent claim due to lack of novelty or obviousness. Therefore, the earlier your priority date, the more prior art you can avoid.

An earlier priority date also positions an inventor better in the global "first-to-file" system, ensuring that even if a competing inventor files a similar patent later, your claim will take precedence. Missing or delaying the priority date risks opening the door to additional prior art references and competing filings.

Different Types of Priority Dates

If your first application was a provisional patent application, then this is your priority date. If your first application was a non-provisional application, then that is your priority date. In the event you filed an international or foreign-filed application first, then that filing date is your priority date.

Priority dates are important to help establish whether another filing or any publicly available document qualifies as prior art against your patent application. In general, any patent applications and publicly available documents filed prior to your priority date are considered prior art.

You can maintain your priority date by filing as early as possible as the United States Patent Trademark Office operates under the rule of who is first to file. Since the priority date can be retained, it also means it can be lost, especially when a patent family is involved. A common way a priority date is forfeited is when the applicant fails to convert a provisional application to a non-provisional application within a year of the provisional application date. If you refile the provisional application, it opens the door to more prior art that may be used against your application.

How to Claim and Maintain a Priority Date

To claim a priority date, you must file a patent application that adequately describes the invention in compliance with enablement requirements. This can be a provisional application, a non-provisional application, or a foreign application under treaties like the Patent Cooperation Treaty (PCT).

Key ways to claim and maintain priority dates include:

  • Provisional to Non-Provisional: File a non-provisional application within one year of a provisional application to retain the provisional filing as your priority date.
  • Foreign and International Applications: If filing first in a foreign country or via a PCT application, U.S. and other national applications must be filed within 12 months to claim the foreign or international filing date as the priority date.
  • Continuation Applications: Continuation, divisional, or continuation-in-part (CIP) applications may claim the priority date of an earlier parent application, provided the subject matter was disclosed in the parent.

Be aware: refiling a provisional application instead of converting it to a non-provisional will reset your priority date, exposing you to additional prior art.

Priority Dates in Complex Patent Families

In patent families with multiple applications, different features may have different priority dates. For example, if new features are added in a continuation-in-part (CIP) application, those features only benefit from the filing date of the CIP, not the original application. Each newly added element starts its own clock for determining applicable prior art.

Therefore, it’s vital to file updates or improvements as soon as possible to ensure that the priority date for each feature is as early as possible, limiting exposure to additional prior art and competitors' filings.

Frequently Asked Questions

  1. What is the difference between a filing date and a priority date?
    The filing date is when an application is officially submitted to a patent office; the priority date may refer to an earlier filing that the application claims to rely on.
  2. Why is the priority date important?
    The priority date establishes what prior art applies against your patent and helps determine who gets the patent in a first-to-file system.
  3. Can I have multiple priority dates for one patent?
    Yes; different features disclosed at different times may have separate priority dates within a single patent family.
  4. How long do I have to file a non-provisional after a provisional?
    You must file a non-provisional application within one year to keep the provisional’s filing date as your priority date.
  5. What happens if I miss the priority claim deadline?
    You lose the benefit of the earlier priority date, potentially exposing your patent to more prior art or losing rights to a competitor.

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