How is opinion evidence evaluated in patent examination?

Opinion evidence in patent examination is evaluated based on several factors:

1. The nature of the matter sought to be established
2. The strength of any opposing evidence
3. The interest of the expert in the outcome of the case
4. The presence or absence of factual support for the expert’s opinion

The MPEP states: “Although factual evidence is preferable to opinion testimony, such testimony is entitled to consideration and some weight so long as the opinion is not on the ultimate legal conclusion at issue.” (MPEP 716.01(c))

However, opinions on legal conclusions are not given weight, though the underlying basis for the opinion may be considered. The case of Ashland Oil, Inc. v. Delta Resins & Refractories, Inc., 776 F.2d 281, 227 USPQ 657 (Fed. Cir. 1985) provides guidance on assessing the probative value of expert opinions.

To learn more:

• Opinion Evidence
• Expert Testimony
• Patent Examination
• Probative Value