49 U.S.C. § 80115 — Limitation on use of judicial process to obtain possession of goods from common carriers

(a) Attachment and Levy. A negotiable bill of lading is a document that lets whoever holds it claim the goods. If a common carrier has issued one for goods it's holding, a court normally can't let someone attach those goods or seize them to pay off a judgment. There are two ways around this rule: someone surrenders the bill to the carrier, or a court blocks ("enjoins") the bill from being transferred to a new holder. If neither happens, the goods stay protected. This protection doesn't apply if the bill was originally given out by someone who didn't actually have the right to give away the goods — in that case, the goods can be attached or levied on normally.

(b) Delivery. The same two conditions apply to delivery. A court can only force the carrier to hand over the goods if the bill of lading is surrendered to the carrier or the court takes physical custody of it ("impounds" it).