40 CFR § 1610.1 - Representation of witnesses in investigations.
(a) Witnesses who are compelled to appear. Witnesses who are compelled to appear for a deposition (i.e., by subpoena) are entitled to be accompanied, represented, and advised by an attorney as follows:
(1) Counsel for a witness may advise the witness with respect to any question asked where it is claimed that the testimony or other evidence sought from a witness is outside the scope of the investigation, or that the witness is privileged to refuse to answer a question or to produce other evidence. For these allowable objections, the witness or counsel for the witness may object on the record to the question or requirement and may state briefly and precisely the ground therefor. If the witness refuses to answer a question, then counsel may briefly state on the record that counsel has advised the witness not to answer the question and the legal grounds for such refusal. The witness and his or her counsel shall not otherwise object to or refuse to answer any question, and they shall not otherwise interrupt the oral examination.
(2) Any objections made will be treated as continuing objections and preserved throughout the further course of the deposition without the necessity for repeating them as to any similar line of inquiry. Cumulative objections are unnecessary. Repetition of the grounds for any objection will not be allowed.
(3) Counsel for a witness may not, for any purpose or to any extent not allowed by paragraphs (a)(1) and (2) of this section, interrupt the examination of the witness by making any objections or statements on the record.
(4) Following completion of the examination of a witness, counsel for the witness may on the record request the person conducting the deposition to permit the witness to clarify any of his or her answers. The grant or denial of such request shall be within the sole discretion of the person conducting the deposition.
(5) The person conducting the deposition shall take all necessary action to regulate the course of the deposition, to avoid delay, and to prevent or restrain disorderly, dilatory, obstructionist, or contumacious conduct, or contemptuous language. Such person shall, for reasons stated on the record, immediately report to the Board any instances where an attorney has allegedly refused to comply with his or her directions, or has allegedly engaged in disorderly, dilatory, obstructionist, or contumacious conduct, or contemptuous language in the course of the deposition. The Board may thereupon take such further action, if any, as the circumstances warrant, including exclusion of that attorney from further participation in the particular investigation.
(b) Voluntary interviews. Witnesses appearing voluntarily do not have a right to have an attorney present during questioning. The Investigator-in-Charge (IIC), in consultation with the General Counsel, may permit a witness to be accompanied by an attorney or non-attorney representative. If so accompanied, the role of the attorney or non-attorney representative is limited to raising objections to questions that are outside the scope of the investigation and to advising the witness with respect to any legal privilege such as, for example, under the Fifth Amendment to the U. S. Constitution. Attorney and non-attorney representatives may not represent more than one witness in each investigation in this fashion, absent the consent of the IIC and the General Counsel.