Many countries prohibit or place restrictions on such operations.
For instance, under the Jones Act of 1920, some US ships are given preferences in the carriage of US domestic cargo and the Merchant Marine Act of 1936 enables the US government to impose penalties on foreign vessels which have been built cheaply by means of subsidy, if they operate in US domestic trade. A number of European countries also prohibit or restrict cabotage. Road transport operated by members of the European Union will be free to operate cabotage trade by mid 1998. Similarly, restrictions were removed on shipping cabotage in 1993, except for island traffic which continues to be restricted until 1999 and, for Greece, 2004. See free trade .