Code of Federal Regulations (alpha)

CFR /  Title 27  /  Part 19  /  Sec. 19.523 Affixing closures.

Each bottle or other container of spirits having a capacity of one gallon (3.785 liters) or less must have a closure or other device securely affixed to the container prior to withdrawal from bond or customs custody. The closure or other device must be constructed in such a manner as to require breaking in order to gain access to the contents of the container. (26 U.S.C. 5301)