Priority Claims

When a patent application claims priority to a parent, grandparent, or other more distant application, a description of that priority claim is placed between the Title and the Background. Examples can be found in thousands upon thousands of issued patents. For example, U.S. 6893641 recites the following priority claim:

The present application is a continuation-in-part (CIP) of U.S. patent application Ser. No. 09/802,862, filed on Mar. 12, 2001 now U. S. Pat. No. 6,468,542, which is a divisional application of U.S. patent application Ser. No. 09/524,508, filed on Mar. 13, 2000 and issued as U.S. Pat. No. 6,316,002, which in turn claims the priority of U.S. provisional application No. 60/158,377, filed on Oct. 12, 1999, wherein all of the U.S. priority applications are herein incorporated by reference.

Some priority claims are quite long and complicated. U.S. 6881822 claims priority to one divisional, five CIP (continuations in part) and six provisionals. It is very common to claim priority to both U.S. and foreign patent applications.

Priority claims are only proper where (a) the child application has at least one inventor in common with the priority parent, (b) the parent was co-pending with the child when the child was filed, and (c) the subject matter being claimed in the child was disclosed in the parent in an enabling manner . An "enabling" disclosure is one that provides sufficient teaching to allow (in the physical sense, not the permissive sense) a person of ordinary skill in the art to make and use the claimed invention with relatively little experimentation.

The patent office usually only addresses the first two issues (common inventor and co-pending), and ignores the issues of enabling disclosure. As a result many patent applications are often issued with priority claims that are invalid. Priority claims can also be valid when a child application is filed, only to become invalid later on. That can occur because the patent attorney considered filing claims to the earlier disclosed subject matter, only to later decide to limit the claims to the newly disclosed subject matter. In such instances an honest attorney will withdraw the relevant priority claims.

The main advantage of a priority claim is that the child application (the one claiming priority) is treated as if it had been filed as of the filing date of the earliest claimed priority application -- with respect to the subject matter disclosed in the priority application. As to later filed subject matter, the child application only has priority back to the date at which the new subject matter was disclosed. Thus, even though patent attorneys, courts, and others talk about a patent having an early priority date, many such patents actually have two, three, or even more priority dates for the different claimed subject matters.

Although applicants are usually quite careful to expressly include all the many generations for their claimed ancestry, it is not strictly necessary to do so. In a 2005 case , the Federal Circuit held that the priority date of a continuing (divisional) application went back to a PCT application, even though the divisional did not expressly recite the priority. In that case the priority arose from the continuation claiming priority to a parent, which itself claimed priority to the PCT.

A few more items of interest. Provisional patent applications are not allowed to claim priority to anything. PCT patent applications can claim priority to patents, but only insofar as they were first published within a year of the PCT filing date . PCT patent applications can also claim priority to patent applications, but only insofar as the filing date of the application was within a year of the PCT filing date. A patent attorney can claim priority to numerous patents and applications at the same time.

It is entirely proper to remove priority claims, and indeed may be advisable under some circumstances. First of all, it is appropriate to remove priority claims where the subject matter recited in the pending claims was not set forth in the documents to which priority was claimed. Indeed, retaining the priority claims in those circumstances adds nothing whatever to the priority of the currently claimed subject matter. Such applications have multiple priority dates, one for the previously disclosed subject matter, and another for the currently disclosed subject matter. If the currently claims are only directed to the new subject matter, then retaining the priority claim is misleading at best, and possibly even fraudulent. In any event there is probably no harm in withdrawing the priority claims under such circumstances.

It may also be proper to remove priority claims to gain additional time to file national regional phase applications. That situation arises because PCT applications never issue as granted patents. They are only place-keepers for national and regional phase applications. If the PCT application claims priority to a provisional application that was filed almost a year earlier, then the applicant only has a maximum of 18 or 19 months from the filing date of the PCT application to file the national/regional phase applications. That usually means a further out-of-pocket expense to the applicant of about US$ 5,000 per country or region. But that expense can be pushed back another 12 months (for a total of 30 or 31 months, or longer depending on the country or region ) simply by removing the claim to the priority date. Of course there is some danger that removing the priority claim will allow intervening prior art to preclude patentability. But where the applicant doesn't have the money to pursue foreign filing with the priority claim in place, and may have the necessary funding if the priority claim is withdrawn, then it may make sense to withdraw the priority claim. A still further potential benefit of withdrawing priority claims is that any resulting patent will issue with a longer patent term (i.e., 20 years from the PCT filing date rather than 20 years from the (withdrawn) priority date). The patent attorney needs to weigh all these considerations.