In the 1990s, Mr. Horn served as the only employment mediator for six years in the U.S. House of Representatives, resolving workplace issues involving Members of Congress, Officers of the House, U.S. Capitol Police Board, and their staff, throughout the U.S. and its territories.  He also managed the adjudicatory process there, implementing hearing procedures, standards of law to apply, and improvements in employee rights, legislatively adopted.  Given his respected ability to work with diverse interests of both parties and institutional knowledge, he was asked to become the U.S. House’s first ADA Coordinator, charged with quickly bringing the House-half of the Capitol Complex into compliance.  Here, he led the implementation of new programs and emergency protocols, as well as initiating changes to historical structures and grounds.  He also designed and managed a workplace ombuds program for House support operations. 
During this time, Mr. Horn also served a leadership role in and was as a founding member of the Federal Interagency Working Groups on Alternative Dispute Resolution (“ADR”).  He also was a member of the American Bar Association and Washington, D.C. Bar Sections on Employment Law, and served as a member of the Federal Ombuds Coalition.
In private practice, Mr. Horn continued to mediate cases for the U.S. District Court for the Federal Circuit.  He also conducted workplace investigations in the federal government and the World Bank Group.  He also served as plaintiff and defense counsel in court and arbitration matters.  He continues to advise on employment agreements, consulting contracts, and personnel policies. 
Mr. Horn has also arbitrated labor cases, and spoke at national conferences on ADR and employment law.