Iron triangle is a political term which is used in the United States politics. It is a policy making relationship in between congress, special interest groups, and government agencies. The connection in between these three points makes a strong bond that creates a sub-governmental situation under the government. They depend on each other to achieve their own goal. Sometime they get so strong that corruption takes over their powers.
Congress helps bureaucracy by funding and giving political supports as necessary. Actually congress is the main source of funding. In return, bureaucracy helps congress by giving policy choices and execution facilities. On the other side, interest groups help bureaucracy by providing congressional support via lobby. In return, bureaucracy helps interest groups by giving facility in lowering regulation, and special favors. Another side, interest group helps congress by giving electoral support. In return, congress helps interest group by giving friendly legislation and oversight.
One of the best examples of iron triangle is the NRA gun control issue. Here the ATF (Bureau of Alcohol, Tobacco, Firearms, and Explosives), NRA (national Rifle Association), and Judiciary are the three points of the triangle. Here, ATF is the federal agency which enforces the laws for controlling of Alcohol, Tobacco, Firearms, and Explosives and NRA is an interest group which wants less gun control from ATF. In return, NRA helps ATF by getting congressional support. Judiciary helps ATF by funding and giving political support.