15 U.S.C. § 1115

(a) Evidentiary value; defenses Any registration issued under the Act of March 3, 1881 , or the Act of February 20, 1905 , or of a mark registered on the principal register provided by this chapter and owned by a party to an action shall be admissible in evidence and shall be prima facie evidence of the validity of the registered mark and of the registration of the mark, of the registrant’s ownership of the mark, and of the registrant’s exclusive right to use the registered mark in commerce on or in connection with the goods or services specified in the registration subject to any conditions or limitations stated therein, but shall not preclude another person from proving any legal or equitable defense or defect, including those set forth in subsection (b), which might have been asserted if such mark had not been registered. (b) Incontestability; defenses To the extent that the right to use the registered mark has become incontestable under section 1065 of this title , the registration shall be conclusive evidence of the validity of the registered mark and of the registration of the mark, of the registrant’s ownership of the mark, and of the registrant’s exclusive right to use the registered mark in commerce. Such conclusive evidence shall relate to the exclusive right to use the mark on or in connection with the goods or services specified in the affidavit filed under the provisions of section 1065 of this title , or in the renewal application filed under the provisions of section 1059 of this title if the goods or services specified in the renewal are fewer in number, subject to any conditions or limitations in the registration or in such affidavit or renewal application. Such conclusive evidence of the right to use the registered mark shall be subject to proof of infringement as defined in section 1114 of this title , and shall be subject to the following defenses or defects: (1) That the registration or the incontestable right to use the mark was obtained fraudulently; or (2) That the mark has been abandoned by the registrant; or (3) That the registered mark is being used by or with the permission of the registrant or a person in privity with the registrant, so as to misrepresent the source of the goods or services on or in connection with which the mark is used; or (4) That the use of the name, term, or device charged to be an infringement is a use, otherwise than as a mark, of the party’s individual name in his own business, or of the individual name of anyone in privity with such party, or of a term or device which is descriptive of and used fairly and in good faith only to describe the goods or services of such party, or their geographic origin; or (5) That the mark whose use by a party is charged as an infringement was adopted without knowledge of the registrant’s prior use and has been continuously used by such party or those in privity with him from a date prior to (A) the date of constructive use of the mark established pursuant to section 1057(c) of this title , (B) the registration of the mark under this chapter if the application for registration is filed before the effective date of the Trademark Law Revision Act of 1988, or (C) publication of the registered mark under subsection (c) of section 1062 of this title : Provided, however , That this defense or defect shall apply only for the area in which such continuous prior use is proved; or (6) That the mark whose use is charged as an infringement was registered and used prior to the registration under this chapter or publication under subsection (c) of section 1062 of this title of the registered mark of the registrant, and not abandoned: Provided, however , That this defense or defect shall apply only for the area in which the mark was used prior to such registration or such publication of the registrant’s mark; or (7) That the mark has been or is being used to violate the antitrust laws of the United States; or (8) That the mark is functional; or (9) That equitable principles, including laches, estoppel, and acquiescence, are applicable.