49 CFR 1548.9: Acceptance of cargo.

(a) Preventing or deterring the carriage of any explosive or incendiary. Each indirect air carrier must use the facilities, equipment, and procedures described in its security program to prevent or deter the carriage onboard an aircraft of any unauthorized person, and any unauthorized explosive, incendiary, and other destructive substance or item, as provided in the indirect air carrier's security program.

(b) Refusal to transport. Each indirect air carrier must refuse to offer for transport on an aircraft any cargo, if the shipper does not consent to a search or inspection of that cargo in accordance with this part, or parts 1544 or 1546 of this chapter.