Applicants file patent applications to protect important inventions. Often, however, minor improvements or modifications may be made to an invention after an application has been filed.
In Australia and New Zealand, it is possible to protect a minor improvement or modification to an invention already described in an existing patent or patent application (the parent patent or patent application) by applying for a patent of addition.
A patent of addition is a useful tool to protect an improvement or modification not disclosed in a parent patent
The key feature of the patent of addition is that the parent patent (or parent patent application if already published) is excluded from the prior art base for assessing inventive step. A claim of a patent of addition cannot be rejected as being obvious in view of the disclosure of the parent patent. This means the patent of addition can be used to protect minor improvements or modifications that do not meet the inventive step threshold in view of the published parent patent.
The exclusion of the parent patent from the prior art base for assessing inventive step for a patent of addition is in stark contrast to the continuation-in-part application available in the US.
The US continuation-in-part application allows an applicant to include new subject matter not disclosed in a parent application. However, unlike a patent of addition in Australia and New Zealand, the published parent application is prior art against any claim in the CIP application that includes new subject matter (12-month grace period provision aside). There is little reason therefore in filing a US continuation-in-part application (as opposed to a standard US patent application) when all claims include new subject matter, other than to create ‘smoke and mirrors’ in relation to priority date.
Another key difference between the patent of addition in Australia and New Zealand and a continuation-in-part application in the US is that a patent of addition may be filed at any time during the pendency of the parent application or term of the granted patent. An applicant may apply for a patent of addition after the original parent patent has been granted. A US continuation-in-part application must be filed while the parent application is still pending.
Those familiar with the US continuation-in-part application should appreciate that the Australian and New Zealand patent of addition is not at all like the US continuation-in-part application. The patent of addition presents significant benefits for applicants in Australia and New Zealand not provided for in the US by the better-known US continuation-in-part.
Why have a patent of addition if the claims of the patent of addition relate to a narrower improvement already protected by a broader claim of the parent patent?
The claims of a patent of addition do not necessarily need to fall wholly within the claims of the parent patent. A patent of addition can therefore be used to broaden the scope of protection provided by a parent patent.
For example, a claim in a parent application may be directed to features A+B+C. A claim of a patent of addition may be directed to features A+B+D, where D is an alternative and new feature not disclosed in the parent patent. Since the scope of the combination of the parent and patent of addition claims extends beyond the scope of the individual parent claim, the overall scope of protection is broadened.
Even if the scope of a claim of a patent of addition does fall wholly within a claim of a parent patent, the patent of addition may still add value to a patent portfolio. A patent of addition presents a further standalone patent that an infringing defendant would need to invalidate in patent litigation proceedings.
One final point that makes a patent of addition an attractive option for protecting improvements or modifications to an invention is that renewal fees are only payable on the granted parent patent. No renewal fees are payable on the granted patent of addition. The granted patent of addition will remain in force for as long as the parent patent at no additional cost.
A standard patent application can be converted to an application for a patent of addition
The one downside to a patent of addition is that its 20-year term is based on the filing date of the parent patent, and will therefore expire when the parent patent expires at the end of its 20 year term (assuming all renewal fees have been paid). The term of a patent of addition is significantly reduced if it is filed many years after the date of the parent patent.
It is therefore worth noting that a standard patent application may be converted to a patent of addition during examination. An applicant may initially file a standard patent application to pursue a 20-year patent term. Should an examiner decide the claims of the patent application lack an inventive step in view of an applicant’s earlier patent, the prior art objection based on the parent patent can be addressed by converting the standard application to an application for a patent of addition.
The patent of addition presents an opportunity to protect a minor improvement or modification to an invention already disclosed in an applicant’s earlier patent application or granted patent. This opportunity is often overlooked by applicants outside Australia and New Zealand not familiar with Australian and New Zealand patent practice.