After reading some previous questions about provisionals, especially from inventors wanting to write them themselfs and consult an attorney only for the non provisional, I was wondering, how much do you have to screw up your application to actually lose the priority on at least some of the claims?

Or to be more specific, I've seen US patents claim different prioritys with continuations and continuations in part, but the patents never mention which priority they actually claim for which claim. So I figure that's for the court to decide.

(I say priority, what I mean is the date considered for prior art, so actually that would be the filing date?)

Now my understanding of provisionals is, that if you add new substantial matter for the non provisional (which seems to be no problem), the new matter gets the new filing date and the old stuff gets the old date. But where does this lead in practice? If I write a very good description of my invention, inclduing everything I can think of and the attorney then rewrites some parts to fit patent speech, (e.g. adding value ranges, defining some things as methods or embodiments where I left out those terms, etc.), could that lead to newer prior art beeing cited against me?

And if yes, to what extend? I'd appreciate the relevant patent law citation, too.

In my opinion this is a rather difficult question and I want to stress that it's always better to let an attorney do that work from the beginning on, because for example of questions like this, but we are getting many questions from inventors that cannot (yet) afford an attorney, plus I'd like to know, too.

  • 1
    Can't wait for @Maca to give his input. But you pick some sensitive issues here, the self-citing prior art issue has been a controversial discussion in Europe (under the name "poisonous divisionals") which only recently ended up in a decision from the Enlarged Board of Appeals of the EPO (G 1/15). Additionally, in Europe you cannot use in-part-continuation US applications for claiming priority, because they are not the first filing, as Article 4C of the Paris Convention provides. Commented Mar 2, 2017 at 13:20
  • Yes yes, I've seen us patents used as prior art for eu applications that were supposed to somehow claim priority backwards. I'd say Europe is easier to grasp when it comes to priorities.
    – user18033
    Commented Mar 2, 2017 at 13:24

2 Answers 2


The rule on this is quite tidily stated at MPEP § 211.05(I)(A) (which I hope will suffice as a legal reference of some nature):

[F]or a claim in a later filed nonprovisional application to be entitled to the benefit of the filing date of the provisional application, the written description and drawing(s) (if any) of the provisional application must adequately support and enable the subject matter of the claim in the later filed nonprovisional application.

This has a nice parallel with the support requirement for the non-provisional too. That is, for each claim of the non-provisional, the description of the non-provisional must adequately support and enable it.

It therefore seems prudent in most cases to have the same description in the provisional and the non-provisional (unless you don't mind losing the benefit of an earlier filing date).

What about rewriting to fit patent speech?

As long as the claims do not rely on details which solely arose during the rewrite, it seems there should be no date issue. Or to put it another way, as long as the claims of the non-provisional are adequately supported and enabled by the description of the provisional, it doesn't really matter what changes have been made to the description of the non-provisional.

However, rewriting seems to present a Library of Alexandria problem. If the changes make no substantive difference, they are superfluous and should not be made. If the changes make a substantive difference, they will threaten the earlier filing date and should not be made.

How much do you have to screw up your application to actually lose the priority on at least some of the claims?

Not very much at all. It is rather easy to lose the earlier filing date if your provisional is deficient or you aren't careful with claim language.

An obiter comparison to Europe

For a British client I work with, we will first file applications in the UK without requesting search or examination. An EP (and other jurisdictions) is filed at 12 months claiming priority to the GB. The GB is then abandoned.

In this manner, the GB (which is never examined and lapses after 12 months) is essentially a provisional for the EP.

  • "the provisional application must adequately support and enable the subject matter of the claim" - would taking that literally not mean that actually not the claim, but just the subject of the claim has to be supported? Has Anyone tried using that in court to sustain a change and the filing date by saying the change was supported by the prov. and the change supported the claim? But it seems to me that those provisionals are not as mad as I thought. Might leave the option to add substantial changes to the non-prov., file claims based on both and hope the older claims have some worth if needed.
    – user18033
    Commented Mar 3, 2017 at 8:07
  • @DonQuiKong Yes, the subject matter of the claim must be supported/enabled, not the claim itself. This is because a claim is basically just a legal statement like "I claim protection for a device having these properties". You can't describe a claim, but you can describe a claimed invention (that is, the subject matter of a claim).
    – Maca
    Commented Mar 3, 2017 at 8:16
  • Ahh, that's where (as said in german) the cat bites it's own tail
    – user18033
    Commented Mar 3, 2017 at 8:18

re how much do you have to screw up your application

Here are some ways that work even in the relatively liberal USPTO:

  1. Add incorrect hard requirements, like using the words "must" or "require". When your later claim will not have these features, this is clearly new matter. "Objects" and "problems solved" fall in this category.
  2. Add unneeded implied requirements. For example, describe only a single way of doing things (nothing is left optional and no alternatives). When you try to claim a different way, or leave out elements, it may be considered new matter.
  3. Admissions. Admit things about prior art, such as what is obvious or known (even if it legally isn't).
  4. Omissions. Leaving out details that are essential for somebody to follow your disclosure, often because you want to "hide" the invention or because you like saying "etc."
  5. Fuzziness. Use terms that are ill-defined and especially if the definition of the invention rests on them. For example, "low power". There is where those "values" in the question come in.
  6. Lack of generalizations. Usually you will want to claim something more general than your specific examples. The USPTO will sometimes allow it. Other patent offices will usually not.
  7. False equivalence. For example, saying or implying that A and B are equivalents, when they are not and in fact, B is patentable and valuable and A is not. Often found in the form of laundry lists of items.
  8. Throw-away ideas. While not affecting the priority of the non-provisional, when you later want to file a new patent to one of these ideas, the publication of the non-provisional will be used against you.

Don't do them!

Outside the USA, the patent offices are often very literally minded and if the claim does not have literal word for word support in the priority document, you can lose the priority.

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