In 1941, Robert Noble, Ellis O. Jones and several other individuals were indicted for violating California's Subversive Organization Registration Law.   The defendants were active in a pro-German group called the Friends of Progress.   Eventually, they were convicted and they appealed.  The Court of Appeal reversed finding insufficient evidence to sustain the convictions.  In the opinion, the Court expressed "grave doubt" about the constitutionality of the law, but deemed it unnecessary to pass on the question.  People v. Noble, 68 Cal.App.2d 853 (1945).

The Subversive Organization Registration Law is still on California's books and can be found at Corporations Code Sections 35000-35302.  The legislature hasn't forgotten about law.  As recently as 2011, it amended the penalty provision for officers and directors.  2011 Stats. ch. 15 § 55.   In general, the law requires subversive organizations to file information with the Secretary of State.  (Although I've asked the Secretary of State's office whether it has received any filings under the law, I haven't yet received a response.)

What I find truly amazing is the definition of "subversive organization".  As you might expect, it includes an organization that advocates the overthrow of the government.  However, it also includes an organization that is "subject to foreign control".  Cal. Corp. Code § 35002(b).  An organization is subject to foreign control if, among other things, it:

It solicits or accepts financial contributions, loans, or support of any kind directly or indirectly from, or is affiliated directly or indirectly with, a foreign government or a political subdivision thereof, an agent, agency, or instrumentality of a foreign government or political subdivision thereof, a political party in a foreign country, or an international political organization.

Cal. Corp. Code § 35003(a).

For more background on Nazi propoganda activities in the U.S. during the 1930s and 40s, the Oviatt Library of the California State University, Northridge has created a very interesting digital collection entitled "In Our Own Backyard: Resisting Nazi Propaganda in Southern California 1933-1945", including this photograph of Noble and Jones.