(a) (1) The testimony of witnesses in inter partes cases may be submitted in the form of an affidavit or a declaration pursuant to § 2.20 and in conformance with the Federal Rules of Evidence, filed during the proffering party's testimony period, subject to the right of any adverse party to elect to take and bear the expense of oral cross-examination of that witness as provided under paragraph (c) of this section if such witness is within the jurisdiction of the United States, or conduct cross-examination
Instead of an oath, affidavit, or sworn statement, the language of 28 U.S.C. 1746 , or the following declaration language, may be used: The signatory being warned that willful false statements and the like are punishable by fine or imprisonment, or both, under 18 U.S.C. 1001 , and that such willful false statements and the like may jeopardize the validity of the application or submission or any registration resulting therefrom, declares that all statements made of his/her own knowledge are true and