ARTICLE 81
All German merchant ships constitute a unified merchant marine.
ARTICLE 82
Germany forms a customs and trade area surrounded by a common customs boundary.
The customs boundary is identical with the international boundary. At the seacoast the shore of the mainland and of the islands belonging to the national territory constitutes the customs boundary. Deviations may be made for the course of the customs boundary at the ocean and at other bodies of water.
Foreign territories or parts of territories may be incorporated in the customs area by international treaties or agreements.
Portions of territory may be excluded from the customs area in accordance with special requirements. In the case of free ports this exclusion may be discontinued only by an amendment to the Constitution.
Districts excluded from the customs area may be included within a foreign customs area by international treaties or agreements.
All products of nature or industry, as well as works of art, which are subjects of free commerce within the Commonwealth, may be transported in any direction across State and municipal boundaries. Exceptions are permissible by authority of national law.