Requirements for Divisional Applications
(1) If a divisional application is not properly divided from its parent application, there is no retroactive effect for the filing date of the divisional application.
(2) If a specification of a parent application describes a feature as essential or describes or suggests that the invention without such feature does not solve a problem to be solved by the invention, it is considered that an invention which does not include the feature is out of the scope of the parent application. If a divisional application divided from a parent application has a claim specifying an invention without such feature, the claimed invention is not disclosed in the parent application and therefore the divisional application is not properly divided from the parent application.
This judgment clarifies the requirements for a divisional application.
It is necessary to draft claims for a divisional application based on the context of the invention of the parent application.
<Writer: Kazunari Tanzawa (Patent Attorney)>
https://www.ip.courts.go.jp/app/files/hanrei_en/890/001890.pdf
Patent Act Article 44
http://www.japaneselawtranslation.go.jp/law/detail/?id=3118&vm=02&re=2