In addition to being new and useful, an invention must also be not obvious in order for a patent to be granted in the U.S.  An inventor does not need to prove non-obviousness in a patent application but may need to rebut a finding by a patent examiner that an invention is obvious.

It may be helpful for an applicant to head off such a finding of obviousness or, at least, lay the groundwork for a rebuttal to such a finding in the patent application.  In order to do so, it is important to understand what rationale the examiner is likely to apply in asserting a finding of obviousness.  Understanding these rationales will help to draft a better patent application that will stand up to such scrutiny.

Statutory Requirement Regarding Non-obviousness
Non-obviousness became a statutory requirement for patentability with the Patent Act of 1952 when 35 U.S.C. 103 was added.  Prior to that time the only statutory requirements for patentability were novelty and utility.  However, even before the Patent Act of 1952 was enacted the courts had imposed a non-obviousness requirement.  Since then, the courts have helped to frame the tests for obviousness.  In view of the recent Supreme Court decision in KSR and an earlier 1966 decision in Graham v. John Deere, the USPTO has recently (October 2007) published examination guidelines for determining obviousness under 35 U.S.C. 103.  The USPTO also has more detailed training examples regarding obviousness which may be of interest.

Guidelines Used to Determine Obviousness
The following brief summary of the guidelines used by the USPTO will highlight the objective standards applied in determining obviousness.

The process to be used by patent examiners in evaluating obviousness is stated as follows:

1. Determine the scope and content of the prior art;
2. Ascertain the differences between the claimed invention and the prior art; and
3. Resolve the level of ordinary skill in the pertinent art at the time of the invention.

With a thorough understanding of the claimed invention, the examiner will match it to the prior art and ascertain the differences between the two.  The examiner will then relate this to the ordinary skill in the art at the time the invention was made.  These are considered factual inquiries.

The next step is for the examiner to resolve whether or not the identified differences would be obvious to a person of ordinary skill in the art.  In making this determination a person of ordinary skill can be imbued with the ability to draw inferences associated with ordinary creativity.   

Rationales Used to Articulate Obviousness
The fact that there are differences between the prior art and the claimed invention is not sufficient.  For patentability, the differences must be so great that bridging the gap would not have been obvious.  The examiner cannot just reach a conclusion that the claimed invention is obvious.  The examiner must articulate reasons drawn from the factual inquiry which explain why the claimed invention would have been obvious.

Several rationales have been enunciated by the USPTO which can be applied by the examiner to support a conclusion of obviousness:

1. Combining prior art elements according to known methods to yield predictable results.

If prior art contains all of the claimed elements and one of ordinary skill could have combined them using known methods to yield only predictable results, then this rationale can be used to indicate obviousness.  It may be helpful in applying this rationale for the examiner to identify a reason why someone of ordinary skill might choose to combine the elements in order to produce the claimed new invention.

2. Simple substitution of one known element for another to obtain predictable results.

If prior art contains a process similar to the claimed invention which can be made into the claimed invention by the substitution of one or more known elements or steps and one of ordinary skill could have made the substitution with predictable results, then this rationale can be used to indicate obviousness.  

3. Use of known technique to improve similar devices (methods or products) in the same way.

If prior art contains a “teaching” or example of a similar or comparable process that had been improved or enhanced in the same way as the process on which a patent is being sought and one of ordinary skill could have applied the known improvement with predictable results, then this rationale can be used to indicate obviousness.

The fact that the known method used in a patent claim had been used in the prior art to improve other similar processes would make this improvement technique part of the ordinary capabilities of one skilled in the art.

4. Applying a known technique to a known device (method or product) ready for improvement to yield predictable results.

If the prior art contains a base process for which the claimed invention can be seen as an improvement and a known technique that is applicable to the process and one of ordinary skill would have been capable of applying this known technique to the prior art with predictable results, then this rationale can be used to indicate obviousness.

The significant factor here is that the known technique used to improve the process on which a patent was sought was already one of the ordinary capabilities of a person of ordinary skill in the art at the time of patent application.  Therefore, applying such technique to improve a known process ready for improvement would have produced predictable results and would have been obvious.

5. “Obvious to try” – choosing from a finite number of identified, predictable solutions, with a reasonable expectation of success.

If a problem (created, for example, by market need or design considerations) can be solved by the testing of a finite number of identified, predictable potential solutions to the recognized need or problem and one of ordinary skill in the art could have pursued these known potential solutions with a reasonable expectation of success, then this rationale can be used to indicate obviousness.

The essential element in this rationale is that when faced with the challenge of the problem one of ordinary skill could be expected, through acquired skill and common sense, to apply known options to find a solution.  If such an approach leads to the anticipated success, it is more likely the result of ordinary skill than innovation.

6.  Known work in one field of endeavor may prompt variations of it for use in either the same field or a different one based on design incentives or other market forces if the variations would have been predictable to one of ordinary skill in the art.

A requirement of this rationale is that prior art, either in the same or a different field as the claimed invention, includes a process similar or analogous to the claimed invention which provides an example of a solution.  If the differences between the claimed invention and such prior art example encompass known prior art variation or principles which would have been apparent to one of ordinary skill in view of identified design incentives or other market forces, then this rationale can be used to indicate obviousness.  It is essential that the application of such variation or principles exhibited in the prior art to the invention being claimed produce predictable results.   

7. Some teaching, suggestion, or motivation in the prior art that would have led one of ordinary skill to modify the prior art reference or to combine prior art reference teachings to arrive at the claimed invention.

If the basic elements of the claimed invention exist in the prior art and there was some teaching, suggestion, or motivation in the prior art that would have led someone of ordinary skill to combine or modify the references into the elements of the claimed invention with a reasonable expectation of success, then this rationale can be used to indicate obviousness.

The teaching, suggestion, or motivation found in the prior art need not be explicit – it may be implicit in the knowledge of one of ordinary skill in the art or be made evident by the nature of the problem to be solved.  An implicit suggestion or motivation may also be provided by the universal desire to improve or enhance commercial processes to make them cheaper, faster, or more efficient, for example.  In this context, if an ordinary practitioner in the art has the knowledge and skills necessary to combine or modify prior art references into a solution, then this rationale can be used to indicate obviousness.