Improvements in the old inventions remained the hall mark of most of the patents barring few breakthroughs which are game changers or pioneer's inventions. Taking a patent for an improvement over the dominant or existing patent is not a cake walk. Every improvement to qualify for patentability must prove to the satisfaction of the patent examiner to be novel, inventive and industrially applicable. To achieve the best scope of protection the applicant is expected to not only to meet these statutory requirements but also craft the claims to remain distinct and away from the boundaries of the dominant patent. The job of crafting such claims becomes all the more difficult as most of the claims in dominant patents are drafted to usually encompass more than the material set out in the specification. This is premised on the fundamental principal of on an adequate disclosure of the invention in the specification. However, the breadth or the reach of a claim is largely a function of two doctrines such as "doctrines enablement" and "doctrines Equivalents". According to the former the specification teaches one skilled in the art how to make and use all the claimed embodiments of the invention covered by the claims. In certain cases, such as pioneer inventions, the inventor gets a benefit of broad coverage of patent claims under the "doctrine of equivalents" which in fact tends to expands the scope of a patent beyond the literal language of the patent's claims particularly during patent infringement disputes. The dominant patents are known to block the subservient patents. But this is not always true. Sometimes they block each other. In such a situation dominant patentee has a broad patent whereas the subservient patentee has a narrower patent on some improved feature of dominant invention but both are essential for development of the technology. This is achieved by crafting the claims in subservient patent in particular fashion to fall outside the boundaries of the dominate patents.
Claiming subservient patent: Jepson route
The question before the drafter of the claims of subservient patent application is how to remain distinct from the dominant patent and claim the improvement as substantial one. This is so as minor improvements or workshop modifications will not qualify for patent eligibility criteria of the examiner at the patent office. The Jepson format is a court recognised format of drafting where the preamble merely states the prior art and portion of the claim appearing after the term "wherein the improvement comprises" mark the inventive step in view of the claimed improvement of certain feature of the prior art or dominant patent. These type of claims are also known as two-part claims in Europe. Under European patent convention it is mandatory where appropriate to draft claims in two parts. Even during prosecution, the EPO examiner would insist the applicant to convert it into two parts using term "characterised" as envisaged under EPC Rule 43(1) that clearly subject the applicant to draft the claims:
Wherever appropriate, claims shall contain a statement indicating the designation of the subject-matter of the invention and those technical features which are necessary for the definition of the claimed subject-matter but which, in combination, form part of the prior art; and a characterising portion, beginning with the expression "characterised in that" or "characterised by" and specifying the technical features for which, in combination with the features stated in the preamble the protection is sought.
In US Law there is a specific template for drafting improvement claims 37 C.F.R 1.75(e). However, instead of the expression "characterised in that" or "characterised by" the expression "wherein the improvement comprises" is supposed to be used in drafting claims relating to improvements. In practise this format is rarely followed in US. Though not mandatory the Indian patent examiners also insist on characterising the claims during prosecution in view of the prior art cited during prosecution of the application. This Two-part format for the improvement claims found favour in Europe and in Indian patent office primarily to magnify small difference over the prior art. It also severs as an effective tool for the drafter to demonstrate the presence of inventive step in view of the overlapping prior art.
Enforcing blocking patents
Practically speaking the astute technique of drafting a subservient patent would past the muster of patent eligibility of examination and fetch you a patent. But such patents carry with it the burden of dominant patent when it comes to its working and enforcement. These patents are known as blocking patent as patentee with a broad patent on an invention "dominate" the narrower as the holder of the narrower ("subservient") patent cannot practice the invention without a license from the holder of the dominant patent. Essentially, the holder of the dominant patent cannot practice the particular improved feature claimed in the narrower patent without a license. The metes and bounds of the narrow patent always remain subservient to the dominant patent when such dispute is agitated before the court seeking infringement relief.
Obviously, it is preferable for an inventor to have a patent that stay free and clear of anyone else's claims. The applicant should not voluntarily characterize their invention as subservient unless there is no other alternative way of drafting. You must seek an expert advice before such request from the examiner is acceded to. The applicant must also be aware that such patents serve as bargaining tool to get favourable cross licensing deal with the dominant patentee. Knowing that both blocking patents are essential for the development of the patented technology it is essential that best drafting technique should be used to stay clear from each other. If the cross licensing efforts fails, the provision of compulsory licensing could be useful for working of the invention by subservient patentee.
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.