49 CFR §1503.635

1. (a)General. A party is entitled to present the party's case or defense by oral, documentary, or demonstrative evidence, to submit rebuttal evidence, and to conduct any cross-examination that may be required for a full and true disclosure of the facts.
2. (b)Admissibility. A party may introduce any oral, documentary, or demonstrative evidence in support of the party's case or defense. The ALJ must admit any oral, documentary, or demonstrative evidence introduced by a party, but must exclude irrelevant, immaterial, or unduly repetitious evidence.
3. (c)Hearsay evidence. Hearsay evidence is admissible in proceedings governed by this subpart. The fact that evidence submitted by a party is hearsay goes only to the weight of the evidence and does not affect its admissibility.