The Supreme Court addressed obviousness considerations in Graham v. John Deere Co. of Kansas City, 383 US 1 (S. Ct. 1966). The case sets forth four factors that a court must consider when evaluating obviousness. The first three factors include the content of prior art, differences between prior art and the claims at issue, and the level of skill of someone of ordinary skill in the art.
While the ultimate question of patent validity is one of law, A. & P. Tea Co. v. Supermarket Corp., supra, at 155, the § 103 condition, which is but one of three conditions, each of which must be satisfied, lends itself to several basic factual inquiries. Under § 103, the scope and content of the prior art are to be determined; differences between the prior art and the claims at issue are to be ascertained; and the level of ordinary skill in the pertinent art resolved. Against this background, the obviousness or nonobviousness of the subject matter is determined.
— Graham v. John Deere Co. of Kansas City, 383 US 1, 17 (S. Ct. 1966).
The fourth Graham factor covers “secondary considerations” such as commercial success and long-felt but unresolved need.
[S]econdary considerations as commercial success, long felt but unsolved needs, failure of others, etc., might be utilized to give light to the circumstances surrounding the origin of the subject matter sought to be patented. As indicia of obviousness or nonobviousness, these inquiries may have relevancy.
— Graham v. John Deere Co. of Kansas City, 383 US 1, 17–18 (S. Ct. 1966).
A court must consider evidence relating to all four Graham factors before determining whether an invention would have been obvious.
We have repeatedly held that evidence relating to all four Graham factors—including objective evidence of secondary considerations—must be considered before determining whether the claimed invention would have been obvious to one of skill in the art at the time of invention.
— Apple Inc. v. International Trade Com'n, 725 F. 3d 1356, 1365 (Fed. Cir. 2013).
A patentee may present a case to rebut any invalidity arguments, including through the consideration of objective indicia (see below).
Once a prima facie case has been established, the burden shifts to the patentee to go forward with rebuttal evidence showing facts supporting nonobviousness.
— Ashland Oil, Inc. v. Delta Resins & Refractories, 776 F. 2d 281, 291–292 (Fed. Cir. 1985).
However, the burden to prove invalidity remains with the party that brings the validity challenge.
Some … have spoken of the obviousness analysis in terms of a "prima facie" case which must then be "rebutted" by the patentee. … Despite this language, however, those cases should not be interpreted as establishing a formal burden-shifting framework.
— In re Cyclobenzaprine Hydrochloride, 676 F. 3d 1063, 1076–77 (Fed. Cir. 2012).