Josh Wolf, 24, has spent almost six months in jail. More time than any journalist in US history for protecting his sources. He was jailed on August 1st of last year when he refused to turn over video that he had shot of an anti-G8 demonstration in San Francisco to a federal grand jury. [includes rush transcript - partial]

Wolf had sold some of the footage to the nightly news as well as posted some on his website. The news broadcast attracted the attention of local and federal law enforcement agents who were investigating clashes between the police and demonstrators at the protest. They later served Wolf a federal subpoena requiring he turn over his unpublished video footage as well as testify about the protesters seen on the tape. When Wolf refused to comply, he was charged with contempt of court and incarcerated.

Wolf’s imprisonment has prompted outcries by advocates for freedom of the press who say it is out of proportion to the scale of the investigation. Lucie Morrillon of Reporters without Borders has stated ''this is one more example of the increasing attacks on confidentiality of sources in the United States, one more blow to investigative journalism and, eventually, to the right for American people to be informed. This is a bad signal sent to the rest of the world.''

On Friday we spoke with Josh Wolf from his jail cell in Dublin California. I began by asking him why he was in prison.

• Josh Wolf, independent journalist. For more information on his case visit Joshwolf.net

We asked a spokesman for the U.S Attorney's office to join us on the program today. They declined our invitation - but Luke Macaulay, spokesperson for the U.S Attorney's office for the Northern District of California sent a statement. It reads: "We have an obligation to the community to investigate and gather evidence of serious crimes. The incident is under investigation so that the grand jury can determine what, if any, crimes were committed. As our court filings state, Wolf videotaped a public demonstration where there may have been an attempt to set a police car ablaze, and where a San Francisco Police Officer's skull was fractured when he was hit from behind by a demonstrator. Six separate judges - one federal Magistrate Judge, two federal District Court Judges, and a panel of three 9th Circuit Judges - have now ruled that this office has issued a lawful subpoena for legitimate investigative purposes, and that the material and testimony in question should be provided to the grand jury."

Martin Garbus is Josh Wolf's attorney. Time Magazine calls him "one of the best trial lawyers in the country," while the National Law Journal has named him one of the country's top ten litigators. He joins me in the studio today.

• Martin Garbus, First Amendment lawyer and a partner in the law firm of Davis & Gilbert LLP. He is an attorney for Josh Wolf. He is also author of the new book, "The Next 25 Years: The New Supreme Court and What It Means for Americans."