As I understand it: there is no 'bright line' to demarcate the boundary. USPTO instructs examiners:

A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102 , if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.

A custom designed measurement device, using existing technology, was developed because the prior-art was not reliable. The novel measurement (unexpectedly to the all) approach yielded unexpected results that dramatically enhanced the utility (value) of the measurement.


A significant amount of trial and error (months) was involved in developing the system: I am concerned that when presented with the final results: the examiner will see how nicely the measurements integrate into the big picture and find for obvious based on that the measurements are used as inputs for another system. Hindsight feeds obviousness bias.

  1. What concrete steps can be taken / avoided to convey that the invention is not obvious?

  2. What questions does the examiner ask himself when determining obviousness?

  3. Is the obviousness issue not a concern in a provisional patent application?
  4. Who decides "ordinary person skilled in the art" and how?
  • Look at the epo “problem solution approach“, its not exactly the same as with the uspto, but it's a good approach to analyse your invention. Additional there are indications for inventive step or something like that, you'll find those at the epo site too.
    – user18033
    Commented Mar 3, 2018 at 12:42
  • One patent system can years to learn. I would stick to learning about the US system if that is where you are filing. In the US, it is not wise to try to point out, in the application, which aspect of your invention is the part that makes it non-obvious. In my understanding of the EPO system your invention is compared to the single reference the examiner sees as the closest. In the EPO - Is a windsurfer a surf board with an added sail or is it a sail boat without most of the boat? It makes a big difference in the identification of the "inventive step", a concept not present in U.S patent law.
    – George White
    Commented Mar 4, 2018 at 0:25
  • @GeorgeWhite epo and uspto aren't that different. Apart from not mentioning the qualification of the posita, everything in your answer would apply to epo. The structure of the problem solution approach helps to understand the differences between ones claims subject matter and the prior art. Using it in a us reply needs a little bit of adaption of the style, but the arguments are very similar. The problem solution approach identifies the differences between any given reference and the subject matter and analyses if the posita would use one of the other references and if yes, what they would
    – user18033
    Commented Mar 4, 2018 at 11:36
  • Arrive at. Which includes checking if they are from the same field. You can use all the arguments in both jurisdictions, and the problem solution approach allows finding those in an imho easier way. Especially when writing an application being aware of both ways and trying to be inventive and non obvious can lead to a better description. Discussing the prior art in the description needs to be done with care though, the problem solution approach should just help identify the important features.
    – user18033
    Commented Mar 4, 2018 at 11:40
  • @DonQuiKong It is a rare US practitioner that discusses the prior art in a patent application.
    – George White
    Commented Mar 4, 2018 at 21:48

1 Answer 1


What concrete steps can be taken / avoided to convey that the invention is not obvious?

I would avoid writing that you used "existing technology". Most inventions are improvements on something that previously existed. As you mention "unexpected result" is one key to not being found obvious. There is also "obvious to try". If there are manageable hand full of different ways to put two things together then you will see that argument from the examiner. One way for you to approach this is to assume you will get an obviousness rejection and understand the ways one fights an obvious rejection.

One way, for example, is to argue that the base reference, when combined with a second reference, is no longer useful for its original purpose and that it's operating mechanism is defeated. A good argument is that there is an element of your claim that is not found in any of the individual references. This is called the "all elements rule". If you claim requires an A, a B a C and a D, the there needs to be an A, a B a C and a D within the multiple references cited in to 103 rejection. And also, "inventions" do not get rejected, specific claim wording is what gets examined and objected to/rejected/allowed.

Another approach to a 103 rejection is to argue that one or more of the references are not from an analogous field. That is a hard argument to win. More practically, you often need to amend a claim to get out from under an obviousness rejection, so you want enough support in the specification that a fallback position has sufficient support. A search might help you have some insight as to what the examiner might find close enough to use a the base reference in a 103 rejection, although they often come up with something not found in your search. We all know about hindsight bias. Applicant arguments will often contain an assertion that the only reason it might seem obvious is that one has read the present application. This sometimes helps.

What questions does the examiner ask himself when determining obviousness?

They want to find the fewest number of references that, together, contain all of the limitations in your claim and that are arguably in the same field. They do not need to think their argument is airtight to make the rejection. They just make it and then it is your job to find the flaw in reasoning.

Is the obviousness issue not a concern in a provisional patent application?

As you will read every time someone uses the term "provisional patent", there is no such thing as a provisional patent. It is a provisional application for a patent. Obviousness is a ground of rejecting a claim. Provisional applications, unless directly converted to a non-provisional application (almost never done - sorry for being too detailed), need not have claims, are never examined, and therefore never subject to any form of rejection. However, the subject matter you end up relying upon to argue against obviousness or to allow amending to get out from a 103 rejection, should find adequate support in your provisional application.

Who decides "ordinary person skilled in the art" and how?

An office action almost never takes official notice of the qualification of the POSITA. They just assert that such an individual would have thought to combine the features of the references to solve the problem. A response to a 103 rejection could argue that the hypothetical person inventing in this field would have a high school education and that it would take a PhD, in some narrow field, of ordinary skill to see this as an obvious invention. I have not seen that and doubt if it would work. I do know that it often comes up in court and can make a difference there.

If you are planning on drafting this yourself you might consider looking up a recent patent in your field in the Public PAIR system of the USPTO. All of the back and forth between the examiner and the applicant is there for the public to study. You will see the original application, the grounds for rejection, and the examiner's responses. I understand that, on average, there are about 2.2 rejections before either there is an allowance or the applicant gives up. Studying a few cases from start to finish might help you draft something that anticipates what treatment it will receive.

  • 1
    Excellent answer. It would be a bit easier to read if you quoted the individual question before each answer.
    – Eric S
    Commented Mar 3, 2018 at 8:50
  • @GeorgeWhite I appreciate the time and effort put into this response. Can I persuade you to update the response with specific cases (that you feel are good) to review in the Public PAIR system?
    – gatorback
    Commented Jun 27, 2018 at 18:25

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