The initial aim of the 1937 Foreign Agents Registration Act was long forgotten: the prosecution of Nazis for interfering with American democracy. But that law is startlingly relevant to the US now.
In the 1930s, the Nazis used exhibitions to create a sense of belonging and support for their ideas. Today's far right groups go online to create a similar sense of community.
The controversial German film-maker was celebrated for her groundbreaking work, but the fact remains she was a prominent Nazi propagandist.