The recent public fight between Apple and the FBI as well as the controversy over the Edward Snowden leaks make it seem as though government spying on American people is a recent phenomenon.

In fact, government surveillance of U.S. citizens goes back over 100 years. Martin Luther King, for instance, was spied on extensively for his opposition to the Vietnam War.

How can spying be so widespread in a country with such strong constitutional protections of privacy?

In the new Learn Liberty video below, University of Tampa professor Abby Hall Blanco partially answers this question by explaining how foreign spying programs eventually become domestic spying programs. That’s because the techniques used to spy on foreign enemies tend to find their way back home.

Put yourself in the government’s position: You have all this fancy spying equipment left over from the war; what else are you going to do with it besides spy on your own citizens? As a result, Professor Hall explains, surveillance has become a permanent government mission rather than a temporary war mission.

The documents leaked by Edward Snowden show how widespread spying has become: nearly all of nearly everyone’s communications are collected.

Those skeptical of government power would argue that this situation is just the logical endpoint of the limited foreign spying that began over a century ago.