What is required for an application to maintain priority from its parent application?

For an application to maintain priority from its parent application, it is essential that the application does not introduce new subject matter. This is a fundamental requirement under patent law to ensure that the new application is effectively a continuation of the earlier filed application, making use of the same inventive concept as the parent application.

The principle behind this requirement is to preserve the original filing date of the parent application for the subject matter that is claimed in the child application. When a new application introduces new subject matter, it extends beyond what was originally disclosed in the parent application. This can potentially undermine the priority claim, as it could lead to a situation where the new application is effectively treated as a separate filing rather than a continuation of the original.

Maintaining priority means that all claims in the child application must be adequately supported by the disclosure of the parent application. Thus, if new matter is added that was not disclosed in the parent, the child application may not be able to claim the benefit of the earlier filing date, thereby jeopardizing its patent validity.

Overall, not introducing new subject matter aligns with the principles laid out in the Manual of Patent Examining Procedure, ensuring that priority is properly maintained across related applications.