I was wondering if any policies or concepts that originated with Lyndon LaRouche's movement or other fringe political movements have made their way into mainstream American policy. By mainstream, I mean policies that have gotten to the point where they have become law or at least formally introduced as a proposed law, or have influenced a court or executive decision.
LaRouche is more of a cult than a political movement. If you'd like I'd suggest going to http://www.larouchecontinued.org which is a forum in which the 40+ year history and continued ongoing operation of the LaRouche organization is discussed.
Alan Greenspan's term at the Federal Reserve comes to mind, although Objectivism wasn't nearly as "fringe" as LaRouche.
Well what precisely do you mean by fringe? Prohibition, as well as plenty of other populist and progressive policies were originally pushed by third parties and civic groups before getting coopted by one or both of the major parties. Is Women's Suffrage a fringe movement, because it started in much the same way. Hell, so did abolition!