Priority date refers to the earliest filing date in collective patent applications. Where only one patent application is being filed, the priority date would certainly be the filing date of the sole application. If an applicant has filed a more than one related patent application, the priority date would be the filing date of the earliest patent registration
that was the first disclosure of the invention. Commonly referred as the priority application, the earliest patent filing may comprise a provisional patent application, a non-provisional patent application or a foreign application.
Priority date is very important to claims of a patent application because knowledge or information available in the public domain before the priority date is taken into consideration while determining whether the claims are entitled to be granted or rejected. Delay in obtaining the priority date may lead to addition of more information or knowledge to the public domain, which may adversely affect possibility of grant of patent.
The term may also refer to the earliest filing date of a unique feature of an invention. Therefore, it is possible to have more than on priority dates if new features were subsequently added in related applications.
###Different types of priority dates
Depending upon the particular situation, the priority date will be the following:
• If your earliest-filed patent application for an invention was a provisional application, then the filing date of the provisional is the priority date.
• If the first filing was a non-provisional application, then the priority date is the non-provisional filing date.
• If your first filed application was an international or foreign filed application, then the filing date of the non US application is your priority date.
###Determining priority date
• A complete patent application will include one or more claims, and each and every claim of the patent application is assigned a unique priority date. That is, each claim in a patent application may have different priority date.
• In cases a where, complete patent application is claiming priority from a previously filed provisional patent application, and if a claim of the complete patent application based on the subject matter already disclosed in the provisional patent application, then the priority date of the claim will be the date of filing of the provisional patent application.
• The Indian Patent law allows an application filed as a complete patent application to be considered as a provisional patent application, if a request is made within the duration of 12 months of filing the above referred complete patent application. A subsequent complete patent application that is filed by claiming priority from such a provisional patent application may have a claim based on the subject matter already disclosed in above referred provisional patent application. In such a case the claim’s priority date will be the filing date of the provisional patent application.
• A completed patent application may be filed by claiming the priority from two or more provisional applications. In case a claim in such a complete patent application relies upon the subject matter already disclosed in one of those provisional patent applications, then the priority date of the claim will be the filing date of the provisional patent application in which the subject matter is already disclosed.
• In another case where, if a claim in such a complete patent application is based on the subject matter disclosed in parts in more than one provisional patent applications, then the priority date of the claim will be the filing date of the latest provisional patent application.
• A complete patent application may be filed within a period of 12 months from previously filed application and claim priority from the same. In case a claim in such a complete patent application is based on the subject matter of the previously filed patent application, then the priority date of the claim will be the filing date of the previously filed patent application.
• Any claim in a divisional patent application will have its priority date as the filing date of an earlier application in which the subject matter on which the claim is based on is first disclosed.
• A complete patent application filed in India may claim priority from one or more applications filed in any convention country. Any claim in such a complete patent application will have the priority date as the filing date of the application in the convention country in which the subject matter on which the claim is based on, was first disclosed.
Primarily, each feature has a priority date of when it was originally filed. Since new features are provided with a later priority date based on when they were first introduced in the patent filing, it’s advisable to file the related applications as soon as possible whenever a new modification is deemed patent-worthy.
For international applications, such foreign filings generally must take place within one year of the United States priority date unless a PCT application is timely filed to extend the deadline for a national application to be filed in each individual foreign country.
Priority date of a claim has a say on what can be considered as prior art to a claim in a patent application. Hence, claims should be drafted in such a way that an earliest priority date is well established, while also considering the scope of protection desired, more particularly when a complete patent application claims priority from more than one patent applications.