29 CFR §458.79

In a hearing concerning an alleged violation of § 458.2 (Bill of rights of members of labor organizations) or § 458.37 (Prohibition of certain discipline), the complainant shall have the burden of proving the allegations of the complaint by a preponderance of the evidence. In a hearing concerning an alleged violation of §§ 458.26-458.30, the Chief, DOE shall have the burden of proving the allegations of the complaint by a preponderance of the evidence. In a hearing concerning an alleged violation of other standards of conduct matters, the District Director shall have the burden of proving the allegations of the complaint by a preponderance of the evidence.