Trading with the Enemy Acts is also a generic name for a class of legislation generally passed during or approaching a war that prohibit not just mercantile activities with foreign nationals, but also acts that might assist the enemy. While originally limited to wartime, in the 20th century these Acts were applied in cases of national emergency as well. For example, in 1940, before the United States entry into World War II the president imposed broad prohibitions on the transfer of property in which Norway or Denmark, or any citizen or national of those countries, or any other person aiding those countries, had any interest, with the exception of transfers which were licensed under the regulations of the Department of the Treasury.
The British Trading with the Enemy Act 1939 was applied to Mandatory Palestine, as to other British-ruled territories. On the creation of Israel in 1948, it was retained as an Israeli law and the various Arab countries named in it as "The Enemy". It is still in force as of 2013, though Egypt and Jordan were removed from its application with the respective peace agreements Israel signed with them.