CFR > Title 37 - Patents, Trademarks, and Copyrights > CHAPTER I—UNITED STATES PATENT AND TRADEMARK OFFICE, DEPARTMENT OF COMMERCE > PART 41—PRACTICE BEFORE THE BOARD OF PATENT APPEALS AND INTERFERENCES > SUBPART D—Contested Cases (§41.100 to §41.158) > 41.158—Expert testimony; tests and data.

41.158—Expert testimony; tests and data.

(a) Expert testimony that does not disclose the underlying facts or data on which the opinion is based is entitled to little or no weight. Testimony on United States patent law will not be admitted.
(b) If a party relies on a technical test or data from such a test, the party must provide an affidavit explaining:
(1) Why the test or data is being used,
(2) How the test was performed and the data was generated,
(3) How the data is used to determine a value,
(4) How the test is regarded in the relevant art, and
(5) Any other information necessary for the Board to evaluate the test and data.