Ley Helms-Burton

"Cuba's 1996 Freedom and Democratic Solidarity Act" (what a misleading title), also known as the "Helms-Burton Act" was enacted by Bill Clinton in March 1996 with the aim of discouraging foreign investment and internationalizing the Cuban blockade. It's beyond questions against international law.

This law codified the regulations of the U.S. economic blockade against Cuba, extended its extraterritorial scope (application to countries other than the one enacted by the law) and establishes the possibility of denying entry to the general directors of international companies (and their families) who have invested in properties "confiscated" after the Castro revolution (Title IV) into U.S. territory.

The Act entered into force in March 1996. However, the application of Title III -which gives the right to sue in U.S. territory anyone who deals with goods confiscated from Americans by the Cuban government- has been systematically suspended by the different presidents of the United States until May 2, 2019, the Donald Trump government activated without any limit, the application of Title III of the Helms-Burton Act.

This "law" is nothing but terrorism against the people of Cuba. You can find many many publications about it in the internet, almost all of it biased in one or the other direction.