U.S. charges last week against two people for allegedly running a Chinese "secret police station" in New York marked the latest case in a broad ramp-up in the use of a century-old law meant to curb the activity of foreign agents.
The law, Section 951, was passed as part of the 1917 Espionage Act - enacted partly to combat resistance to the World War One draft - and makes it illegal to operate in the United States subject to a foreign government's direction or control without notifying the Attorney General.
