45 CFR 681.26: How will the hearing be conducted and who has the burden of proof?

(a) The ALJ conducts a hearing in order to determine whether a defendant is liable for a civil penalty, assessment, or both and, if so, the appropriate amount of the penalty and/or assessment. The hearing will be recorded and transcribed, and the transcript of testimony, exhibits admitted at the hearing, and all papers filed in the proceeding constitute the record for a decision by the ALJ.

(b) NSF must prove a defendant's liability and any aggravating factors by a preponderance of the evidence.

(c) A defendant must prove any affirmative defenses and any mitigating factors by a preponderance of the evidence.