Electronic snooping by the government has higher standards, more controls and a completely different justification than in the days of King.
Where the enemy was once communism, it is now terrorism. Investigators focus less on the private lives of highly public individuals such as King, and more on the thousands of people whose private communications and activities could come under the watchful eyes of government interceptors.
Government officials say the modern surveillance programs involving telephone calls and Internet activity are carefully controlled by the courts, Congress and the White House.
But we don't know everything about these programs because they are by their very nature, secret.
The power of today's NSA
Still, old habits die hard. The most recent revelations involving the National Security Agency show that the government can peer into intimate moments in the lives of everyday Americans.
And it has happened before.
In his 2008 book about the NSA, "The Shadow Factory," author James Bamford wrote about an NSA employee named Adrienne Kinne, who was quoted saying she made a personal decision to erase intimate communications that had been intercepted between Americans living abroad and in the United States.
"A lot of times I would just delete them. ... I would just do that because I didn't feel comfortable leaving it in the system and I didn't. ... A lot of times you could tell they were calling their families, waking them up in the middle of the night because of the time difference. And so they would be talking all quiet and soft, and their family member is like half asleep -- incredibly intimate, personal conversations -- and I just can't believe they were frigging recording them, and I don't know why they would ever have to to begin with."
Fast-forward to this week.
A story first reported by The Wall Street Journal asserted that NSA officers have on several occasions "channeled their agency's enormous eavesdropping power to spy on love interests."
So perhaps, if a guy like J. Edgar Hoover had access to a tool such as the NSA, it might have been hard for him to resist using it any way he saw proper.
Even on a civil rights hero.