37 CFR § 2.11 - Requirement for representation.
(a) An applicant, registrant, or party to a proceeding whose domicile is not located within the United States or its territories must be represented by an attorney, as defined in § 11.1 of this chapter, who is qualified to practice under § 11.14 of this chapter. The Office cannot aid in the selection of an attorney.
(b) The Office may require an applicant, registrant, or party to a proceeding to furnish such information or declarations as may be reasonably necessary to the proper determination of whether the applicant, registrant, or party is subject to the requirement in paragraph (a) of this section.
(c) An applicant, registrant, or party to a proceeding may be required to state whether assistance within the scope of § 11.5(b)(2) of this chapter was received in a trademark matter before the Office and, if so, to disclose the name(s) of the person(s) providing such assistance and whether any compensation was given or charged.
(d) Failure to respond to requirements issued pursuant to paragraphs (a) through (c) of this section is governed by § 2.65.
(e) Providing false, fictitious, or fraudulent information in connection with the requirements of paragraphs (a) through (c) of this section shall be deemed submitting a paper for an improper purpose, in violation of § 11.18(b) of this chapter, and subject to the sanctions and actions provided in § 11.18(c).
(f) Notwithstanding § 2.63(b)(2)(ii), if an Office action maintains only requirements under paragraphs (a), (b), and/or (c) of this section, or only requirements under paragraphs (a), (b), and/or (c) of this section and the requirement for a processing fee under § 2.22(c), the requirements may be reviewed only by filing a petition to the Director under § 2.146.