37 C.F.R. §2.17(b)

1. (1) Recognition of practitioner as representative. To be recognized as a representative in a trademark case, a practitioner qualified under §11.14 of this chapter may:
2. (i) File a power of attorney that meets the requirements of paragraph (c) of this section;
3. (ii) Sign a document on behalf of an applicant, registrant, or party to a proceeding who is not already represented by a practitioner qualified under §11.14 of this chapter from a different firm; or
4. (iii) Appear in person on behalf of an applicant, registrant, or party to a proceeding who is not already represented by a practitioner qualified under §11.14 of this chapter from a different firm.
5. (2) Signature as certificate of authorization to represent. When a practitioner qualified under §11.14 of this chapter appears in person or signs a document pursuant to paragraph (b) of this section, his or her personal appearance or signature shall constitute a representation to the Office that he or she is authorized to represent the person or entity on whose behalf he or she acts. The Office may require further proof of authority to act in a representative capacity.

To be recognized as a representative, a qualified practitioner may:

1. File a power of attorney signed by the individual applicant or registrant or someone with legal authority to bind a juristic applicant or registrant (e.g., a corporate officer or general partner of a partnership);
2. Sign a document on behalf of an applicant or registrant who is not already represented by a qualified practitioner from a different firm; or
3. Appear in person on behalf of an applicant or registrant who is not already represented by a qualified practitioner from a different firm.

37 C.F.R. §2.17(b). A foreign attorney or agent who has not been recognized by the OED Director pursuant to 37 C.F.R. §11.14(c) or registered as a patent agent pursuant to 37 C.F.R. §11.6(c) may not be recognized as a representative.

Generally, as long as no other qualified practitioner from a different firm has been previously appointed, it is not necessary for a qualified practitioner to file a power of attorney or obtain special authorization in a trademark case. A qualified practitioner who appears in person or signs a document on behalf of an applicant or registrant will be accepted as the representative of the applicant or registrant. 37 C.F.R. §2.17(b)(2). (A qualified practitioner may also be recognized as the applicant’s representative if the practitioner is identified as the attorney of record in the application, even when the application is signed by the applicant.). Neither a telephone call nor an e-mail from a qualified practitioner satisfies the "appearance" requirements of 37 C.F.R. §2.17(b). However, after issuance of an Office action to a pro se applicant and prior to response, a qualified practitioner may satisfy the appearance requirement by submitting a signed document into the record stating that the practitioner represents the applicant and requesting that the Office records be updated to indicate that he or she is the attorney of record.

An individual not meeting the requirements of 37 C.F.R. §2.17(b) will not be recognized as a representative, and may not sign responses or authorize amendments to an application. See TMEP §611.03(b) regarding signature on such documents.

Once the USPTO has recognized a qualified practitioner as the representative of an applicant or registrant, the USPTO will communicate and conduct business only with that practitioner or with another qualified practitioner from the same United States firm. The USPTO will not conduct business directly with the applicant or registrant, or with a qualified practitioner from a different firm, unless the applicant or registrant files a new power of attorney or revokes the previous power, or the previously recognized practitioner files a request to withdraw. 37 C.F.R. §§2.17(c)(2), 2.18(a)(7), 2.19. See TMEP §§ 604.02 regarding duration of recognition, 605.03 regarding associate powers of attorney, 606 regarding revocation of power of attorney, and 607 regarding withdrawal of attorney of record.

See TMEP §§609.01 and 609.02–609.02(f) regarding changing the correspondence address, and TBMP §§114–114.08 regarding representation of parties to Board proceedings.