Even though it is usually described that continuation patents are mainly used to broaden or change claims about a disclosure made in a parent patent application, I am led to understand they can also introduce real improvements to the 'invention' disclosed in the parent patent (and then the priority date shifts on the timeline accordingly etc.).

It's also well known that for some domains, e.g. software, patent applications that do not go through the expedited examination process take about a year or more until they are first examined. So a patent application stays 'live' for the sake of being able to submit a continuation application deriving from it, for a bit of a long time (any comments up to here?).

My question here is how is the novelty of a continuation application - one that adds or modifies the original invention, due to improvements to the invention made since the original - how is its novelty judged by the examiner....

Namely does the continuation need to be sufficiently novel compared to the parent (i.e. a big leap of novelty even compared to the parent), or does it more merely need to be novel compared to what would have been considered novel at the time of the parent submission (which seems unfair as it sort of lets the continuation leap back in time to an earlier date). I find this very troubling...

1 Answer 1


Nothing troubling going on. No "new matter" is allowed in any continuation other than a continuation-in-part. In a continuation-in-part the examiner essentially treats the application as if it didn't have any priority benefit from the earlier applications in the chain. If prior art is found that pre-dates the actual filing of the CIP the examiner can use that prior art in a rejection and put the burden of showing that the topic in question was sufficiently covered in an earlier filing in the chain on the applicant.

Regarding your own previous work, it can be used against you a year after it was published. At that time it is treated like any other prior art even if it is in the parentage chain of a CIP. So a CIP that only adds mater obvious in light of the original filing can have claims to that addition allowed as long as it has not been a year since the original application was published.

And yes, it take years to get a patent or to have a patent go abandoned. A chain of child applications with the specification and drawings unchanged can extent for years. However the check on that is patent term ends 20 years from the earliest claimed priority. Extending a chain of continuations for 15 years would result in a patent with a five year life.

  • So a CIP could be just seen as a convenient way (in a way, for both the patent office and the applicants) to 'upgrade' an application rather than submitting an entirely new one that repeats some of the original... wouldn't you say? or I'd go further in saying it is just an official procedure for submitting a new disclosure that is similar to one already submitted, that follows a different bureaucratic path.
    – matanox
    Dec 28, 2013 at 10:51
  • 1
    If the applicant is adding something significant and plans to have claims only to the new aspects it is better for the applicant to file a "new" application so any resulting patent extends 20 years from the filing date rather than 20 years from the parent. In any case the fees are the same for any of these filings.
    – George White
    Dec 28, 2013 at 17:52
  • Well, then one may conclude that "new" applications and regular continuation cover all the same needs as a CIP. CIP looks like a hybrid of the two cases.... it may seem like it's just a convenience mechanism for filing an evolved application with both claims to originally disclosed subject matter and claims to new subject matter in one piece of application. Other than the case that filing a "new" application puts to waste the earlier priority date as much as it is applicable to each claim. maybe some additional nuances about it (?). Anyway thanks again!
    – matanox
    Dec 29, 2013 at 8:39

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