Proving that a patent is invalid because it was in commercial use at least one year before the patent was taken out requires that the defendant prove their case:
A) with a preponderance of the evidence.
B) beyond a reasonable doubt.
C) beyond a preponderance of the evidence.
D) by clear and convincing evidence.
E) with some evidence.

Question

Quizplus · Accepted Answer

Principles under the patent law have led courts to determine that proof of invalidity must be made by "clear and convincing evidence" instead of the "preponderance of the evidence" standard that exists in most civil cases. This makes it more likely that a patent will be upheld in court.

Proving That a Patent Is Invalid Because It Was in Commercial