(a) A brief of an amicus curiae may be filed only by leave of the Commission or the presiding officer granted on motion with notice to the parties, or at the request of the Commission or the presiding officer, except that leave must not be required when the brief is presented by the United States or any agency or officer of the United States. The brief may be conditionally filed with the motion for leave. A brief of an amicus curiae must be limited to questions of law or policy.

(b) A motion for leave to file an amicus brief must identify the interest of the applicant and must state the reasons why such a brief is desirable.

(c) Except as otherwise permitted by the Commission or the presiding officer, an amicus curiae must file its brief no later than 7 days after the initial brief of the party it supports is received at the Commission. An amicus curiae that is not supporting either party must file its brief no later than 7 days after the initial brief of the first party filing a brief is received at the Commission. The Commission or the presiding officer must grant leave for a later filing only for cause shown, in which event the period within which an opposing party may answer must be specified.

(d) A motion of an amicus curiae to participate in oral argument will be granted only in accordance with the requirements of § 502.241. [Rule 78.]