As a young reporter for the Chicago Tribune in the months following 9/11, Will Potter was already growing weary of reporting on cops, crime, and shootings in the city. On a whim during some time off, he decided to help a group of activists hand out leaflets opposing animal testing.

“It wasn’t what journalists usually do,” says Potter, now 37. “But I was feeling like I wasn’t making a difference in the world as a reporter.”

Shortly after that, two FBI agents showed up at his door and told him he could be put on a terrorism watch list if he didn’t help them gather information about the animal activists he had helped. The agents knew that both he and his then girlfriend had applied to graduate school and warned them that the student aid they had applied for could be pulled if they didn’t cooperate. “ ‘Everything changed after 9/11,’ ” he recalls them saying.

“I couldn’t believe they were using that rhetoric of terrorism against someone handing out leaflets,” says Potter. “That was really shocking to me.”

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The encounter ultimately altered his career path. While the charges against him for handing out leaflets were dropped—and nothing ever came of the veiled threats from the FBI agents—Potter spent the next 15 years immersed in the politics and policing of dissent, and how the “war on terrorism” has affected our civil liberties.

His 2011 book, Green Is the New Red: An Insider’s Account of a Social Movement Under Siege, would expose the way the “terrorist” label has been used by the FBI to go after animal rights and environmental activists. Potter’s reporting on the amended Animal Enterprise Terrorism Act, which gave the government greater authority to prosecute radical animal rights activists, exposed what he believes to be an assault on free speech in defense of corporate profits for Big Agriculture, all under the pretense of fighting terrorism. His story is at the center of a new episode of the Brian Knappenberger documentary series Truth and Power, narrated by Maggie Gyllenhaal and airing on Pivot. A clip from the episode is available below:

In 2006, Potter testified before Congress on the Animal Enterprise Terrorism Act, arguing that it could criminalize peaceful protest. Since then, he has covered the passage of and fight against so-called ag-gag laws in states across the country, such as Idaho’s 2014 Agricultural Security Act, which made it a crime to secretly film any kind of abuse on commercial farms.

“Big Ag is one of the largest industries on the planet, and also one of the most substantial contributors to political campaigns,” Potter says, adding that, at the same time, Big Ag is heavily subsidized by the U.S. government and escapes regulation—all farm animals, for example, are exempt from animal cruelty protections under the Animal Welfare Act. “As with pretty much any story in American politics, if you want to find out who is really in charge, you need to follow the money. In this case, Big Ag has very deep pockets and isn’t reluctant to wield that kind of influence at both the state and federal level,” he says.

However, as Potter points out, public awareness of ag-gag laws has begun to make a difference. For instance, the Idaho law was struck down in federal court last year when a judge ruled that it was an unconstitutional criminalization of free speech rights. As a result, similar laws in other states have come under scrutiny. Still, as Potter points out, there’s a long way to go.

“Big Ag is digging in and being more aggressive,” he says, “and because the ‘war on terror’ ethic is so ingrained in the operation of the FBI, it’s going to take substantial public pressure to shift this in another direction.”

But Potter says public exposure is the biggest threat to the industry.

“When these tactics are exposed, like criminalizing people simply for taking photos and videos, they don’t stand up to public scrutiny.” he says.

Unfortunately, says Potter, there’s still not enough public awareness of the tactics used by Big Ag to squelch free speech. Not until it becomes clear, as in other eras—the “Red Scare” under Senator Joseph McCarthy, for example—that we have gone down a dark path will real change occur.

“There has to be a turning point when a real critique of these policies takes place,” he says. “That has to be a starting point in undoing them.”

Since that encounter with the FBI in Chicago when he was a young reporter, he hasn’t been threatened again—but he has been watched.

“There have been FBI agents at my speaking events,” Potter says, “and after I filed a Freedom of Information request, I found out they were keeping a file on me. It’s pretty chilling and insidious, the fear all this creates. People think twice about speaking up. But you have to move past feeling fear.”

He says he’s motivated to continue the fight because it cuts to the heart of the First Amendment: “It’s about who has rights to information. Unless we address that core problem, all other social justice efforts will be irrelevant.”

Truth and Power airs Fridays at 10 p.m. ET/PT on Pivot, Participant Media’s television network. You can also learn about protecting your civil liberties in the digital age by exploring “Know Your Rights,” a Pivot-supported initiative from the ACLU of Southern California.