NEW YORK (Bloomberg) – If you think someone is watching you, paranoia may not be the only explanation.

So suggests First Amendment lawyer Martin Garbus in "Shouting Fire: Stories from the Edge of Free Speech", which is currently airing on HBO.

Garbus, most famous for defending neo-Nazis who wanted to march in Skokie, Illinois, and representing Daniel Ellsberg in the Pentagon Papers case, warns that Americans face growing threats from a government with unparalleled snooping powers, compliant courts and fellow citizens with axes to grind.

The 75-minute show, hosted by Garbus's daughter, filmmaker Liz Garbus, begins with a paean to the First Amendment, which her father calls the "cornerstone of democracy" and a "miracle".

Garbus says the miracle isn't universally revered, especially in wartime, when dissidents are likely to pay a price for speaking their mind.

One segment takes up the case of University of Colorado professor Ward Churchill, fired in 2007 after an investigation found him guilty of academic misconduct, including plagiarism and fabrication.

Garbus, grey and soft-spoken, contends that Churchill's real sin was an inflammatory post-9/11 essay in which he argued that the attacks were partially payback for US foreign policies – "chickens coming home to roost", as Churchill says in an interview. That analysis picked up steam in 2009, when Churchill won an unlawful termination suit. (Garbus wasn't involved in the suit.)

Another case examined on the programme involves Debbie Almontaser, the Yemeni-American who founded the Khalil Gibran International Academy, an Arabic-English public school in New York.

Almontaser was accused of sympathising with terrorists before the school had even opened, a charge given widespread publicity by the New York Sun and New York Post. The show indicates she was the victim of a hysteria-driven smear job, though Garbus says there was no libel. Free speech, we are reminded, can have unpleasant consequences.

That was also a lesson learned by Chase Harper, a California high-school student who was removed from class for wearing a T-shirt condemning homosexuality on religious grounds. Though no students complained, he was sent to the vice principal's office, where he says he was told, "If your faith is offensive, you have to leave it in the car".

"Are we in the United States?" Harper asks during an interview.

Well, yes. The show makes clear that protecting freedom of speech has been a struggle since the get-go, tapping into HBO's "John Adams" miniseries to hear Adams and Thomas Jefferson debating the merits and drawbacks of untrammeled tongues.

Garbus recalls the late 1970s uproar in Skokie, when he supported a neo-Nazi group's right to march in a heavily Jewish city with many Holocaust survivors. (Though the neo-Nazis won their court case, they never did march in Skokie.) Garbus, who is Jewish, said it was a "horrendous experience" for him, but he felt the principle of free speech should apply to everyone.

The future should offer plenty of opportunities for First Amendment lawyers, according to the show, which says the government is using the war on terror as an excuse to curb dissent and snoop on Americans who haven't been accused of any crime.

At the 2004 Republican Convention in New York City many marchers were arrested during non-violent demonstrations. The programme says there were 1,801 arrests at the convention, compared to 688 at the infamous 1968 Democratic Convention in Chicago, where police beat anti-war protesters in the streets.

Technological advances and a lax court system have contributed to increased government surveillance, Garbus says.

Perhaps most disturbing is the public support for curbing speech.

Before 9/11, the show says, 20 percent of Americans agreed the First Amendment "goes to too far". After the attacks, the number rose to 50 percent. (No specific poll is cited.)

The show includes interviews with liberals and conservatives, including former special prosecutor Kenneth Starr, who investigated allegations against then-President Bill Clinton; First Amendment attorney Floyd Abrams; conservative writer David Horowitz; and Columbia University history professor Eric Foner.

They all have their say, which everyone who supports free speech should applaud.