AOP Community Resources

Patent Dates

Patent Dates Overview

Each patent has a number of dates that can impact a patent’s role in a Study.  For the Study patent, the dates dictate the timeframe of the Study and the range of dates that are available as prior art.  For a submission, the dates determine whether the patent is eligible to be submitted.  However, there are several instances where one date holds priority over another depending on the history of the patent and any applications.

Generally, a patent expires 20 years from the filing date of the corresponding patent application.  Specifically, the patent term (its effective lifespan) begins on the day the patent was issued and ends 20 years from the filing date of the corresponding patent application. Also, US patent applications are published in the USPTO Gazette 18 months from the filing date of the patent application.  Thus, even though a patent has not yet been granted on a patent application, the latter becomes available for public inspection a year and a half from the date the patent application was filed.

Filing, Publication and Issue Dates

The filing date issued by the USPTO on a patent application is of critical importance to an inventor or patent owner because it determines who has priority over the right to file a patent application for an invention.  For example, many European countries, and more recently, the US, have first-to-file patent systems. This means that the entity who was the first to file a patent application for an invention is the only one whose patent application will be allowed to go through the entire process of examination for a possible issuance of a patent.  Thus, the system is essentially on a “first-come, first-served” basis.

In addition to the patent application’s filing date, US patent applications are now published 18 months after the filing date of the application, subject to some exceptions.

Finally, once the original or amended claims of a patent application have been approved by the examiner, the patent is granted and the specific date of grant is called the “issue” or “grant” date (also called “day of patent”).  Thus, there would be effectively two publication dates for recent US patents: (a) publication date arising from the now required 18-months-from-filing publication date and (b) the publication date corresponding to the issue date.

As with the filing dates of patent applications, their publication dates are also of critical importance, particularly to those entities who intend to file patent applications after the publication of an earlier-filed patent application. This is because they have the potential to adversely affect the patentability of patent applications filed after the publication dates of earlier-filed patent applications.

Filing Dates: Actual vs. Effective

A US patent that claims priority to one or more provisional, non-provisional, or continuing patent applications will have two filing dates: an actual filing date and an effective filing date.

Let us assume that a first inventor, “Mike”, filed a provisional application on March 24, 2001.  Then, almost a year later, Mike filed a non-provisional application on March 23, 2002.  In this case, the “actual filing date” of the Mike’s non-provisional application is March 23, 2002.  However, the non-provisional patent application can also claim an earlier “effective filing date” if the non-provisional application claimed priority to the earlier-filed provisional application.

By claiming priority to the earlier-filed provisional application, the non-provisional application becomes entitled to an effective filing date of March 24, 2001, which is the same as the actual filing date of the corresponding provisional application.  Thus, almost a year later, a provisional application allows one to file a non-provisional application based on the provisional application.  The non-provisional application is treated as if it were filed on the same date the provisional application was filed.  This option benefits Mike because it allows him to (a) utilize an early filing date and (b) achieve a one year grace period for the filing of the final documents for the subsequent non-provisional patent application.

The advantage provided by an earlier effective filing date can be seen in the case in which a second  inventor, “Sarah”, filed a non-provisional patent application on November 12, 2001 for the same invention disclosed in the provisional application filed on March 24, 2001 (see timeline directly below).

  • March 24, 2001 – Provisional application, Mike
  • November 12, 2001 – Non-provisional, Sarah
  • March 23, 2002 – Non-provisional based on provisional, Mike

In a contest over priority, Mike wins over Sarah.  Even though Mike filed the non-provisional application several months after Sarah filed her own non-provisional application, Mike has priority because the effective filing date of his non-provisional application is actually March 24, 2001.  Thus, in a first-to-file patent system, which the US recently adopted, Sarah loses out to Mike. As a result, Sarah will not be allowed to pursue the prosecution of a patent application for the same invention.

Filing Dates in a Patent Search

In determining priority over the invention claimed in the above-mentioned patent, the relevant filing date of the patent would be the filing date of the earliest-filed patent application listed under the “US Application Data” heading in the patent’s abstract page.  Thus, one must utilize the earliest filing date (in this case, March 24, 2001) listed under the “US Application Data,” rather than the actual filing date listed opposite the header “Filing Date.”

As an actual example, consider US Patent No. 7,385,359 B2 (‘359 Patent).  This is an example of a US patent that contains a variety of dates on its bibliographic page.

  • Date of Patent (grant or issue date) – June 10, 2008
  • Filing Date – Nov. 20, 2001
  • Prior Publication Data – Oct. 17, 2002
  •  Various dates corresponding to the provisional and continuing applications listed under the “Related U.S. Application Data”

Among the various dates listed under the “Related U.S. Application Data,”  the earliest listed date is December 17, 1997, which is the filing date of the provisional application with application number 60/071,281.  When the patent is being considered as potential prior art, the above dates in the patent would be arranged in order of decreasing importance (from the earliest to the most recent) according to the following sequence:

  • Earliest claimed priority date (effective filing date) – December 17, 1997
  • Actual filing date of the patent application – November 20, 2001
  • Prior Publication Date – October 17, 2002
  • Grant date – June 10, 2008

As prior art, a reference must pre-date the effective filing date of a patent being examined for possible invalidity (the Study Patent).  That means that the date of the prior art must be earlier than the effective filing date of the patent of interest.  This prior art date in the case of ‘359 Patent above would be, in principle, any of the above-listed dates that is earlier than the effective filing date of the patent of interest.

For example, if the Study patent has an effective filing date of January 23, 2003, both the patent’s cited publication date (10/17/2002) and effective filing date (10/17/1997) are earlier than January 23, 2003, so both dates can be used as the date of US patent 7,385,359.  However, if the effective filing date or earliest claimed priority date of the Study patent is, for example, July 31, 2001, the only date listed in US patent 7,385,359 (‘359 patent) that can be used as its prior art date would be ‘359 patent’s effective filing date of December 17, 1997 since this is the only date listed in the patent that is earlier than the Study patent’s effective filing date of July 31, 2001.