[Townhall] Under the Constitution, there are three branches of government. The FBI is not one of them. Instead, the FBI was created to assist the president in his job to enforce laws. Members of the FBI are called "agents" because of their agency relationship with the president. The term 'Special' Agent was added by Hoover to exempt them from the Military Draft. The Bureau's animus towards the American military continues to this day.
During World War II and then the Red Scare, the FBI's mission expanded to gather intelligence against spies. Here, too, the FBI was assisting the Commander in Chief. Even the word "intelligence" connotes this fact. The purpose was to help the president act intelligently against domestic threats.
The FBI’s domestic intelligence gathering function caused understandable discomfort on the left. In 1970s apocrypha, President Nixon couldn’t wait to get the goods on undesirables like the Smothers Brothers. Or so we were told by the Smothers Brothers, back when the FBI's mission creep cast it as the Gestapo.
In response to Nixon’s perceived overreach, liberal Idaho (before those words were an oxymoron) Senator Frank Church set up a commission to investigate domestic surveillance abuses. Technology, by then, permitted federal agencies to capture huge amounts of wire communications without disclosing their eavesdropping to Americans who were being surveilled.
Senator Church stated his concerns on an episode of Meet the Press:
"If this government ever became a tyrant, if a dictator ever took charge in this country, the technological capacity that the intelligence community has given the government could enable it to impose total tyranny [against those who] combine together in resistance to the government."
The result of Senator Church’s work was the Foreign Intelligence Surveillance Act of 1978 (FISA). It provided that the FBI could not use its technological capacity to secretly gather intelligence against an American without first going to court with credible evidence that the citizen was a spy.