BOB GARFIELD: This is On the Media. I'm Bob Garfield.

BROOKE GLADSTONE: And I'm Brooke Gladstone. In July of 2005, leaders from the major industrialized nations convened at the Gleneagles Hotel in Perthshire, Scotland for the 31st annual G8 Summit. That same week, 5,000 miles away in San Francisco, a group of anarchists and other anti-globalization activists marched in protest of the summit, first peacefully and then increasingly with violence. Newspaper vendor boxes were overturned in the streets, storefront windows were damaged, the skull of at least one police officer was fractured and a city police car was vandalized. Self-described video journalist and activist Joshua Wolf caught much of the action on tape. [VIDEO CLIP] [SOUND OF SIRENS]

MAN: Get back! Get back! Get back! Get back! Everybody get back! Everybody step back!

WOMAN: He is not resisting arrest and you guys are taking excessive force!

MAN: I said get back! Everybody get back! [CROWD NOISE]

MAN: Get back! [END VIDEOTAPE]

BROOKE GLADSTONE: An edited version of Wolf's footage, including the sound you just heard, was published on his blog, joshwolf.net, but it's the part that wasn't published that has now landed Josh Wolf in jail. Law enforcement officials believe that unaired portions of his videotape contain evidence of who the perpetrators were, but Wolf has refused a federal grand jury subpoena to turn over the outtakes, citing special legal protections he's owed as a journalist. It's a case that has some asking since when are journalists no longer citizens, while others rally to his defense, including David Carlson, president of the Society of Professional Journalists. David, welcome to On the Media.

DAVID CARLSON: Thank you, Brooke. It's a pleasure to be here.

BROOKE GLADSTONE: So, David, the SPJ has pledged financial support for Josh Wolf's defense. Explain to me, if Wolf has physical evidence that may be pertinent to a criminal investigation, journalist or not, why shouldn't he have to turn it over?

DAVID CARLSON: Well, when journalists can be turned into an arm of law enforcement, which is essentially what the federal prosecutor is attempting to do, then that means journalists will have more trouble gathering information. And eventually, if journalists start turning over their information to the government, the next time somebody's vandalizing a police car and sees a camera, they'll break the camera, beat up the journalist and then vandalize the police car.

BROOKE GLADSTONE: Now, a case like this would normally fall under California jurisdiction, which has one of the country's most broadly protective shield laws. But this case is being handled by the U.S. Attorney's office and is playing out in a federal court. How is this episode justified as a federal case?

DAVID CARLSON: Well, essentially the local authorities chose not to attempt to get Josh to turn over his tape, but the federal government came along and said that because San Francisco police department receives federal grant money and a police car that may have been purchased with some of this federal grant money was vandalized, that makes it a federal case. It seems a very tenuous connection. The thing that many of us are having great difficulty with in this case is trying to understand the federal government's motivation. Why are they so interested in prosecuting a 24-year-old blogger, essentially, who happened to witness an event and who says that his tape doesn't have what the police are looking for anyway? Now, this is purely conjecture, but the only thing that occurs to me is does it have something to do with the fact that this was a demonstration against the G8? And if that's the case, and again it is only speculation, but if that's the case, if we're seeing the federal government begin to prosecute people in order to send this message that if you oppose us, we will find you, that is of great concern.

BROOKE GLADSTONE: What if Josh Wolf had simply been an observer with a camera with no intent to distribute his video? Should he be then impelled to turn it over to the police?

DAVID CARLSON: Well, that's an interesting question. I think that – [PAUSE] – hmm – that average citizens could be compelled to turn over information.

BROOKE GLADSTONE: Does posting a video on a personal blog constitute an act of journalism?

DAVID CARLSON: Well, I believe shield legislation needs to focus on the act of journalism and not on who is a journalist. We believe that shield legislation should define a journalist as anyone who gathers or processes information for dissemination to a larger audience.

BROOKE GLADSTONE: You know, for decades, many in mainstream journalism, including the Society of Professional Journalists, I believe, opposed the idea of shield laws, and especially a federal shield law.

DAVID CARLSON: Well, it's very true, and the thinking was that our rights come from the public's rights, and we are not seeking to be placed on some pedestal that gives us special privileges that average citizens don't have. Yet when we have journalists being jailed almost routinely, we feel there's no choice.

BROOKE GLADSTONE: You know, we've seen in recent polls the suggestion that the public is less and less sympathetic to the mission of journalism. If the public is less and less inclined to believe that the media are working on their behalf, then is fighting a case like this for Josh Wolf, whose journalistic credentials are questionable, at least, worth the fight?

DAVID CARLSON: Well, I agree that that's a legitimate question. In some ways, you could almost look at what's happened for the past four or five or even six years as a continuous effort on the part of the government to marginalize journalists and to make journalists less able to keep the public informed, which, of course, is the root of democracy. Now, with a case like this –- all right, there may be parts that don't look good -– you know, the public saying all those journalists wants extra consideration that other people don't have – but what is the lesser of two evils here?

BROOKE GLADSTONE: All right. David, thank you very much.

DAVID CARLSON: My pleasure, Brooke. Thank you.

BROOKE GLADSTONE: David Carlson is a professor of journalism at the University of Florida and the president of the Society of Professional Journalists.