39 CFR 952.18 - Evidence.
(a) Except as otherwise provided in these rules, the Federal Rules of Evidence shall govern. However, such rules may be relaxed to the extent that the presiding officer deems proper to ensure a fair hearing. The presiding officer may exclude irrelevant, immaterial, or repetitious evidence.
(b) Testimony shall be under oath or affirmation and witnesses shall be subject to cross-examination.
(c) Agreed statements of fact may be received in evidence.
(d) Official notice, judicial notice or administrative notice of appropriate information may be taken in the discretion of the presiding officer.
(e) Authoritative writings of the medical or other sciences may be admitted in evidence, but only through the testimony of expert witnesses or by stipulation.
(f) Lay testimonials may be received in evidence as proof of the efficacy or quality of any product, service, or thing sold through the mails, in the discretion of the presiding officer.
(g) The written statement of a competent witness may be received in evidence provided that such statement is relevant to the issues, that the witness shall testify under oath at the hearing that the statement is in all respects true, and, in the case of expert witnesses, that the statement correctly states the witness's opinion or knowledge concerning the matters in question.
(h) A party which objects to the admission of evidence shall explain the grounds for the objection. Formal exceptions to the rulings of the presiding officer are unnecessary.