iron triangle

noun2

1. •
   (US) The policy-making relationship among the congressional committees, the bureaucracy (executive, sometimes called “government agencies”), and interest groups or lobbyists.
2. •
   Any self-reinforcing power structure, whether intentional or accidental, formal or informal.

   • Together, agribusiness, shipping companies and NGOs form what some have called the “iron triangle” of special interests, blocking reform of the controversial in-kind system. — 2012