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IP Cases & Commentary – Details

18 March 2010

What is Priority?

Nicholas Malden

The filing date of a patent application is of central importance to the application process in particular because it determines the “prior art” against which the claims of the patent application are assessed for novelty and inventive step.

What is a priority application?

When filing a patent application it is possible under certain circumstances to “claim priority” from an earlier patent application made by the same applicant for the same invention. This earlier patent application may be referred to as the “priority application”. Significantly, for the purposes of determining the prior art that is available for assessing the patentability of the later patent application, the filing date of the priority application is then used.

What is the priority period and how long is it?

In order to claim priority from an earlier application, the later application should be filed within the priority period, which is 12 months from the date of filing of the earlier application.

What if the priority period is missed?

In principle if the later application is filed more than 12 months after the earlier priority application, then the priority claim to the earlier application is invalid and the filing date of the later application determines the prior art against which novelty and inventive step are assessed.

There are some very limited mechanisms by which it is possible to claim priority from an earlier application filed more than 12 months beforehand, but these typically require the applicant convincingly to demonstrate that circumstances beyond his control prevented filing within the 12 month priority period.

Are multiple priority applications allowed?

Yes, a patent application may claim priority from more than one priority application, provided that the patent application is filed with the 12 month priority period of all the claimed priority applications.

How do you make a priority claim to a priority application?

To claim priority from an earlier application, the later application should be filed within the 12 month priority period of the earlier application. The earlier application may be an application for a patent application, a utility model or a utility certificate. Priority from design applications may not be claimed for a patent application.

The earlier application must have been made by the same applicant (or his predecessor in title) as the applicant for the later application.

The earlier application may be one that has been filed in a different country, as long as that country and the country in which the later application is being filed are party to an agreement to respect each other’s priority claims. Most industrialised countries are party to either the Paris Convention for the Protection of Industrial Property or the World Trade Organisation, which provide such agreements.

The right to priority in respect of a later application is available for the same person that filed the earlier application. In view of this, if the rights in the parent application have been assigned, the assignment of rights must be recorded for the parent application prior to filing the later application if the later application is to be filed in the name of the assignee(s).

For a valid entitlement to priority, the “same invention” that is claimed in the later application should be disclosed in the earlier application. This requirement is (depending on the jurisdiction) generally strictly interpreted. For example, a later application that replicates the contents of the earlier application from which priority is claimed, will have a valid entitlement to priority for the whole subject-matter. However, if an invention has been expanded upon during the priority year and the later application is broader and/or contains subject-matter not present in the earlier application, the later application will not have a valid entitlement to priority for the whole subject-matter.

A further requirement is that the earlier application from which priority is claimed is the earliest such application relating to that invention that has been made by the applicant. If an even earlier application relating to that invention has been made by the same applicant this will invalidate the priority claim. For example, if an applicant files patent application P3, claiming priority from earlier patent application P2, then the existence of an even earlier patent application P1 by that same applicant filed more than 12 months before the filing date of P3 will invalidate the priority claim from P3 to P2 for any subject-matter common to P1 and P2.  The only way to avoid this situation is to ensure that (if P2 is to be filed in the same country as P1), by the filing date of P2, P1 is unconditionally withdrawn, abandoned or refused without being published or leaving any rights outstanding or having served as a priority application for any other application.

Can I add a priority claim after filing?

A declaration of a priority claim is preferably made when the later application is filed. However, it is possible to add a priority claim for a limited period after filing the later application. For a UK or an EP patent application, generally a priority claim can be added within 16 months of the earliest priority date claimed and must be made in time to allow its inclusion in the publication of the later application.

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