26 U.S.C. § 5370: Losses

In the case of loss by theft, unless the Secretary shall find that the theft occurred without connivance, collusion, fraud, or negligence on the part of the proprietor or other person responsible for the tax, or the owner, consignor, consignee, bailee, or carrier, or the agents or employees of any of them; and In the case of voluntary destruction, unless the wine was destroyed under Government supervision, or on such adequate notice to, and approval by, the Secretary as regulations shall provide. In any case in which the wine is lost or destroyed, whether by theft or otherwise, the Secretary may require by regulations the proprietor of the bonded wine cellar or other person liable for the tax to file a claim for relief from the tax and submit proof as to the cause of such loss. In every case where it appears that the loss was by theft, the burden shall be on the proprietor or other person liable for the tax to establish to the satisfaction of the Secretary, that such loss did not occur as the result of connivance, collusion, fraud, or negligence on the part of the proprietor, owner, consignor, consignee, bailee, or carrier, or the agents or employees of any of them.