UPDATE – 11:45 AM EST Questions for Guardian editor-in-chief and Metropolitan police commissioner & assistant Met commissioner have concluded. The hearing has moved on to general counterterrorism matters. I will be putting up a post on the hearing in the next couple of hours.

In moments, a parliamentary hearing before the House of Commons Home Affairs Committee will begin where Guardian editor-in-chief Alan Rusbridger will be subjected to questioning for his role in publishing journalism on documents from former National Security Agency contractor Edward Snowden.

The scheduled testimony has provoked outrage among press freedom groups. Particularly, the Reporters Committee for Freedom of the Press (RCFP) in the United States sent a letter to the committee that was signed by the Associated Press, American Society of News Editors, McClatchy Company, New York Times Company, New Yorker, Washington Post and others.

The letter condemns the British government for moves that seem to be intended to silence the press:

It is thus unwise and counterproductive to react to the reporting on disclosures from Edward Snowden by reflexively invoking security concerns to silence the press or to accuse a news organization of aiding terrorists simply by providing citizens with information they need to know. Published reports in The Guardian on the Snowden disclosures have been prepared with the care and sensitivity to security concerns that editors have long demonstrated. We understand that both GCHQ and the NSA were provided an opportunity, in advance of publication, to comment and alert the journalists to particular security concerns. The reporting has been both responsible and, given the intense displeasure of those in power, courageous.

To the rest of the world, it appears that press freedom itself is under attack in Britain today. British politicians are publicly calling for the criminal prosecution of The Guardian for having published true, accurate, and newsworthy information. A Scotland Yard investigation has been launched. “D notices” have been threatened. And the Prime Minister has raised the prospect of seeking an injunction prohibiting The Guardian from publishing any further intelligence revelations. These aggressive actions intimidate journalists and their sources. They chill reporting on issues of national security and on the conduct of government more generally.

Investigative reporter Carl Bernstein had an open letter published by The Guardian which he called Rusbridger’s appearance before the Commons today as “dangerously pernicious, an attempt by the highest UK authorities to shift the issue from government policies and excessive government secrecy in the United States and Great Britain to the conduct of the press—which has been quite admirable and responsible in the case of the Guardian, particularly, and the way it has handled information initially provided by Mr. Snowden.”

Bernstein applauded the record of the press since World War II in “handling national security information since World War II, without causing harm to our democracies or giving up genuine secrets to real enemies.” He contrasted it with the conduct of governments, prime ministers and presidents, which have been responsible for “over-classification, disingenuousness and (sometimes) outright lying.”

Indeed, Bernstein concludes that he has been called to testify at a moment when “governments in Washington and London seem intent on erecting the most serious (and self-serving) barriers against legitimate news reporting — especially of excessive government secrecy — [that] we have seen in decades.” (Full open letter can be read here.)

Ben Emmerson, a leading UN official on counterterrorism and human rights, had a column published at The Guardian as well, where he called it “outrageous to accuse the Guardian of aiding terrorism by publishing Snowden’s revelations.”

“Attacking the Guardian is an attempt to do the bidding of the services themselves, by distracting attention from the real issues. It is the role of a free press to hold governments to account, and yet there have even been outrageous suggestions from some Conservative MPs that the Guardian should face a criminal investigation,” Emmerson wrote.

Emmerson concluded, “The claims made that the Guardian has threatened national security need to be subjected to penetrating scrutiny. I will be seeking a far more detailed explanation than the security chiefs gave the intelligence committee. If they wish to pursue an agenda of unqualified secrecy, then they are swimming against the international tide. They must justify some of the claims they have made in public, because, as matters stand, I have seen nothing in the Guardian articles that could be a risk to national security. In this instance the balance of public interest is clear.”

I’ll have a post on Rusbridger’s testimony after the hearing is over. Watch Rusbridger give his testimony and answer questions from the committee here at 10 am EST.

For more background on what has led up to this moment, here’s an overview of some of the attacks on journalism in the UK since The Guardian began to publish stories on documents from Snowden. And here is a post on efforts to set a precedent for policing journalism.