U.S. environmental activists who are working to halt the production and use of fossil fuels could be required to register as foreign agents if Congress gets serious about enforcing an existing law.

There was some potential movement in that direction last October when Senate Judiciary Committee Chairman Chuck Grassley, R-Iowa, introduced legislation that would put some teeth into the Foreign Agents Registration Act. The law, which was first passed in 1938, calls for individuals and organizations to provide full disclosure when they are working to advance the public policy interests of a foreign government.