39 C.F.R. § 3010.322 – Evidence—general.

(a) Form and admissibility. In all hearings, relevant and material evidence which is not unduly repetitious or cumulative shall be admissible. Witnesses whose testimony is to be taken shall be sworn, or shall affirm, before their testimony shall be deemed evidence in the proceeding or any questions are put to them.
(b) Documentary material—(1) General. Documents and detailed data and information shall be presented as exhibits. Exhibits should be self-explanatory. They should contain appropriate footnotes or narrative explaining the source of each item of information used and the methods employed in statistical compilations. The principal title of each exhibit should state what it contains or represents. The title may also contain a statement of the purpose for which the exhibit is offered; however, this statement will not be considered part of the evidentiary record. Where one part of a multi-part exhibit is based on another part or on another exhibit, appropriate cross-references should be made. Relevant exposition should be included in the exhibits or provided in accompanying testimony. Testimony, exhibits and supporting workpapers prepared for Commission proceedings that are premised on data or conclusions developed in a library reference shall provide the location of that information within the library reference with sufficient specificity to permit ready reference, such as the page and line, or the file and the worksheet or spreadsheet page or cell. Where relevant and material matter offered in evidence is embraced in a document containing other matter not material or relevant or not intended to be put in evidence, the party offering the same shall plainly designate the matter offered excluding the immaterial or irrelevant parts. If other matter in such document is in such bulk or extent as would unnecessarily encumber the record, it may be marked for identification, and, if properly authenticated, the relevant and material parts may be read into the record, or, if the Commission or presiding officer so directs, a true copy of such matter in proper form shall be received in evidence as an exhibit. Copies of documents shall be delivered by the party offering the same to the other parties or their attorneys appearing at the hearing, who shall be afforded an opportunity to examine the entire document and to offer in evidence in like manner other material and relevant portions thereof.
(2) Status of library references. Designation of material as a library reference and acceptance in the Commission's docket section do not confer evidentiary status. The evidentiary status of the material is governed by § 3010.321(g)(3).
(c) Commission's files. Except as otherwise provided in paragraph (e) of this section, any matter contained in a report or other document on file with the Commission may be offered in evidence by specifying the report, document, or other file containing the matter so offered and the report or other document need not be produced or marked for identification.
(d) Public document items. Whenever there is offered in evidence (in whole or in part) a public document, such as an official report, decision, opinion or published scientific or economic statistical data issued by any of the Executive Departments (or their subdivisions), legislative agencies or committees, or administrative agencies of the Federal Government (including Government-owned corporations) and such document (or part thereof) has been shown by the offeror thereof to be reasonably available to the public, such document need not be produced or physically marked for identification, but may be offered in evidence as a public document item by clearly identifying the document and the relevant parts thereof.
(e) Designation of evidence from other Commission dockets.
1. (1) Parties may request that evidence received in other Commission proceedings be entered into the record of the current proceeding. These requests shall be made by motion, shall explain the purpose of the designation, and shall identify material by page and line or paragraph number.
2. (2) In proceedings to consider the appeal of a Postal Service determination to close or consolidate a post office conducted pursuant to part 3021 of this chapter, these requests must be made at least six days before the date for filing the party's direct case. Oppositions to motions for designations and/or requests for counter-designations shall be filed within three days. Oppositions to requests for counter-designations are due within two days.
3. (3) In all other proceedings subject to this section, these requests must, in the absence of extraordinary circumstances, be made at least 28 days before the date for filing the party's direct case. Oppositions to motions for designations and/or requests for counter-designations shall be filed within 14 days. Oppositions to requests for counter-designations are due within seven days.
4. (4) In all proceedings subject to this section, the moving party must submit two copies of the identified material to the Secretary at the time requests for designations and counter-designations are made.
(f) Form of prepared testimony and exhibits. Unless the presiding officer otherwise directs, the direct testimony of witnesses shall be reduced to writing and offered either as such or as an exhibit. All prepared testimony and exhibits of a documentary character shall, so far as practicable, conform to the requirements of § 3010.124(a) and (b).
(g) Copies to parties. Except as otherwise provided in these rules, copies of exhibits shall be furnished to the presiding officer and to the parties or counsel during a hearing, unless the presiding officer otherwise directs.
(h) Reception and ruling. The presiding officer shall rule on the admissibility of evidence and otherwise control the reception of evidence so as to confine it to the issues in the proceeding.
(i) Offers of proof. Any offer of proof made in connection with any ruling of the presiding officer rejecting or excluding proffered oral testimony shall consist of a statement of the substance of the evidence which counsel contends would be adduced by such testimony; and if the excluded evidence consists of evidence in documentary or written form, or of reference to documents or records, a copy of such evidence shall be marked for identification and shall constitute the offer of proof.
(j) Official notice of facts. Official notice may be taken of such matters as might be judicially noticed by the courts of the United States or of any other matter peculiarly within the knowledge of the Commission as an expert body. Any party shall, on timely request, be afforded an opportunity to show the contrary.