One of the most frightening things, I think, is the capacity for retroactive searching, so you can go back in time and trace who someone is in contact with and where they've been.

People are starting to understand that the devices we carry with us reveal our location, who we're talking to, and all kinds of other information.

I think one of the most shocking things is how little our elected officials knew about what the NSA was doing. Congress is learning from the reporting and that's staggering. Snowden and [former NSA employee] William Binney, who's also in the film as a whistleblower from a different generation, are technical people who understand the dangers.

So my first experience was that I had to do a reboot of my expectations. Like fantastic, great, he's young and charismatic and I was like wow, this is so disorienting, I have to reboot. In retrospect, I can see that it's really powerful that somebody [Snowden] so smart, so young, and with so much to lose risked so much.

In all my work, I'm interested in trying to understand the human consequences of government policies.

In all my work, I'm interested in understanding big issues through the lives of individuals.

When the most important decisions are made in secret, we lose our ability to check the powers that control.