Reading through the book "Patent it Yourself", I come across this from "Inventor's Commandment 10":

Your patent application should not contain any statements that the courts could possibly use against you to limit the claims of your invention -- that is, do not mention any problems with the prior art that are not already known, or that your invention doesn't solve, ...

First, how could an invention's claims be limited by mentioning a problem with the prior art that is not "already known"? Couldn't an invention solve a problem that is known to the inventor but not yet to the industry at large? And, supposing the 'unknown' problem is only a subset of the problems the invention solves, how would mentioning such an unknown problem be used to limit the invention's claims?

And secondly, how could mentioning a problem that the invention doesn't solve limit the invention's claims? I see how mentioning an irrelevant problem would be a distraction unrelated to the application, but not sure I understand how that could actually limit the claims made.

I do not plan to mention any such problems with prior art in my application, but would like to understand better how mentioning such 'unknown' or irrelevant problems could limit a claim.

1 Answer 1


I think the wording in the edition of David Pressman's book that you quote is not a clear way to express this concern but there is a real issue.

Patent law is not science and is not even always logical or self-consistent. (You can google when "and means or" and when "at least one" excludes the case of one, in a patent context.)

The plain language of the claims are what define your protected invention but the plain language often needs interpretation by the court - a process called claim construction.

In claim construction one principle is that the claims are understood in light of the specification and a somewhat competing principle is that you do not import limitations from the specification into the claims. Some courts have tried to determine "what did the inventor really invent" or "what did the inventor really think their invention is" outside of reading the claims. Some crazy conclusions have been reached.

One category of these judgements have been excluding seemingly infringing things that fall within the words of the claim. The logic is that that a mention of shortcoming of a prior solution is taken to mean that the current invention does not have that shortcoming. So the judges might decide that an alleged infringing product that has the deficiency must not infringe even though it meets all the explicit elements of a claim.

If you said an old solution weighed over 10 lbs and lighter solutions were needed. Even if there is no limitation regarding weight in a claim, a judge could decide an 11 lb. infringing device doesn’t really infringe even though it fits within the words of a claim because of a perceived assertion by the inventor that weight was a critical “objective” of the invention.

Speaking of invention, avoid the word invention in your specification.

  • 1
    When I've taught "invention as a process" I've explained that sometimes you also have to invent (and patent) the inferior methods precisely because of the potential that an apparently infringing invention which has one of the problems which currently exist in the art. "The present invention overcomes the fact it had to weigh 11 pounds or more". Okay, I make an 11 pound version what's claimed by not doing something the inventor thought was "important". Jul 28, 2022 at 20:55
  • 1
    A prolific inventor once suggested to me that after inventing something one should then invent something that solved the same problem less expensively, not worrying about leaving out non-critical functionality. And that might the one to productize.
    – George White
    Jul 29, 2022 at 1:09
  • 1
    If someone takes that advice, they should then investigate the less expensive patent and follow that same approach. I'm convinced that there are a lot of patents to be had making less perfect inventions which can at least by produced without the monopoly restrictions of the more perfect inventions. Jul 29, 2022 at 17:49

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .