filing a PCT application, one should be aware of the priority deadline. That is
the deadline you need to meet so that your next filing is legally granted the
filing date of a previously filed application (i.e., the priority date). The
Paris Convention (which guides portions of the PCT) has a 12-month priority
deadline. That goes for U.S., Paris Convention Members and PCT Member States.
Article 4.C(4) of the Paris Convention dictates that the 12-month window for filing a PCT application commences on the filing date of the earliest application in the family. Let’s consider an example in which a provisional application was filed, a nonprovisional application was filed, and one is considering filing a PCT application. If the nonprovisional application claims priority to the provisional application, then the earliest filing date in the family is the filing date of the provisional application. The PCT application would need to be filed within 12 months from the filing date of the provisional application.
If the nonprovisional application does not claim priority to the provisional application, then the PCT application can claim priority to the nonprovisional application if the PCT application is filed within 12 months of the filing date of the nonprovisional application. Consider the situation in which a provisional application, P1, is filed on 1/1/2000; a nonprovisional application, P2, is filed on 1/1/2001; and a PCT application, P3, is filed on 1/1/2002.
A) P3 cannot claim priority to P1 because the 12-month deadline is 1/1/2001.
B) P3 cannot claim priority to P2, if P2 claimed priority to P1. The priority claim creates a family in which the earliest filing date is the filing date of P1. Thus, the 12-month deadline is again 1/1/2001.
C) P3 can claim priority to P2, IF P2 did not claim priority to P1 at the time of filing P2 AND P1 was abandoned or withdrawn at the time of filing P2.
In situations (A) and (B) above, P3 can still be filed even though a priority claim is barred by the 12-month window. The problem is that P1 and P2 will likely be used to establish that P3 lacks novelty and an inventive step, which theoretically will bar P3 from issuing into a patent. This problem can be overcome if P1 and P2 are abandoned prior to being published AND prior to filing P3. This tactic, however, will establish a new priority date—the filing date for P3—which could be problematic.
To further complicate the analysis, some foreign countries, but not all, will NOT consider P1 or P2 as prior art if P3 is filed before P1 or P2 were published or before the invention was publicly disclosed. It should be noted that this nuance includes a scenario where P3 is filed in a country that is different than the country in which P1 and P2 were filed.