In Microsoft Corp. v. i4i Ltd. Partnership, 131 S. Ct. 2238, 564 U.S., 180 L. Ed. 2d 131 (2011) the Supreme Court of the United States stated:
Under §282 of the Patent Act of 1952, “[a] patent shall be presumed valid” and “[t]he burden of establishing invalidity of a patent or any claim thereof shall rest on the party asserting such invalidity.” 35 U. S. C. §282. We consider whether §282 requires an invalidity defense to be proved by clear and convincing evidence. We hold that it does.
Microsoft Corp. v. i4i Ltd. Partnership, 131 S. Ct. 2238 (2011) (emphasis added).
The issue of evidence with respect to 35 U.S.C. §101 takes center stage in the oral argument of CMG FINANCIAL SERVICES, INC. v. PACIFIC TRUST BANK, FSB, No. 2014-1855 (Fed. Cir. Sept. 15, 2015). [Link]
As you can see from the Rule 36 Judgment [link], the panel punted on the issue — which reminds me of another quote:
It is emphatically the province and duty of the judicial department to say what the law is. Those who apply the rule to particular cases, must of necessity expound and interpret that rule.
Marbury v. Madison, 5 U.S. 137, 177 (1803).