19 CFR § 165.3 - Power of attorney.
(a) When required. Any submission made under this part other than by a principal or its employees may be filed by a person acting as agent or attorney in fact for the principal; a power of attorney must specifically authorize such person to make, sign, and file the submission or grant unlimited authority to such person.
(b) Exception. No power of attorney is required for an attorney at law to act as agent or attorney for the principal. The signing of a submission as agent or attorney for the principal by the attorney at law will be considered a declaration by the attorney that the attorney is currently an active member in good standing of the highest court of a state, possession, territory, commonwealth, or the District of Columbia, and has been authorized to sign and file the submission for the principal.
(c) Execution -
(1) Corporation. A corporate power of attorney to file the submissions described in paragraph (a) of this section must be signed by a duly authorized officer or employee of the corporation.
(2) Partnership. A partnership power of attorney to file the submissions described in paragraph (a) of this section must be signed by at least one member in the name of the partnership or by at least one duly authorized employee of the partnership, provided the power recites the name(s) of all of the members.
(3) Other persons. A power of attorney filed by a person other than a corporation or partnership must be signed by that person or an employee of that person who has the legal authority to act on that person's behalf when filing the submissions described in paragraph (a) of this section.
(d) Revocation. Any power of attorney will be subject to revocation at any time by written notice given to and received by CBP, Office of Trade.
(e) Proof. CBP will require proof of execution of a power of attorney, where applicable, the first time that an agent makes a submission on behalf of any interested party during an investigation or administrative review of a determination as to evasion. CBP may require proof of authority to execute a power of attorney pursuant to paragraph (c) of this section, at any point during the proceedings described in this part.