Often an examiner will refer to the prima facie case of obviousness:

1. There must be some suggestion or motivation to combine references (“the TSM test”).
2. There must be a reasonable expectation of success.
3. The prior art references must teach or suggest all of the claim limitations.

The applicant can overcome the prima facie case by establishing that any one of the three criteria is not met.

A recent decision by the Supreme Court addressed the TSM test and determined that it had been applied too rigidly. See KSR v. Teleflex, 550 U.S. 398 (2007). In response to the decision, the United States Patent and Trademark Office supplemented the TSM test with six additional tests. These tests include: (A) whether combining prior art elements according to known methods will yield predictable results; (B) whether simple substitution of one known element for another will obtain predictable results; (C) whether the use of a known technique to improve similar devices (methods, or products) can be applied in the same way; (D) whether applying a known technique to a known device (method, or product) ready for improvement yields predictable results; (E) whether it would be "obvious to try" (i.e. whether the inventor was merely choosing from a finite number of identified, predictable solutions, with a reasonable expectation of success); and (F) whether 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 are predictable to one of ordinary skill in the art. See Manual of Patent Examining Procedure § 2143.

Note that the examiner is required to articulate his or her reasons for concluding that the references at issue can be combined. See id. These reasons cannot be based on merely conclusory language. See id. at § 2142. As a result, an applicant can attack an assertion of obviousness by attacking the examiner’s purported rationale for combining references.

Alternatively, an applicant can present secondary evidence of nonobviousness. The secondary evidence includes:

1. Skepticism of invention by others
2. Long-felt need in the art
3. Failure of others to create invention
4. Commercial success
5. Licensing
6. Adoption by others in the industry