Good journalism will be a much more difficult task following the High Court judgment yesterday. The freedom of expression, enshrined in the Constitution and relied upon by journalists, is merely a function of the public's right to know. This, in turn, relies on journalistic disclosure of information secreted or obscured from public scrutiny. The best story for any journalist is what someone, somewhere - usually in high places - doesn't want the public to know.
The argument for allowing all citizens, rather than an elite, to choose their own government rests fundamentally on the belief that those citizens are capable of making informed choices. In complex societies, those choices are seldom informed directly. People rarely witness the events and processes that affect their lives, or learn about them from direct contact with those who do. It is the great privilege of journalists to record events as they unfold, to observe them as the eyes and ears of the citizen, and to write about them as the first, maybe even the second, drafts of history in the making.
The core function of journalism is to provide the raw material of democratic choice, the information on which, in a healthy democracy, facts, arguments, interpretations and value judgments can be based. In a world where citizens are bombarded with images, slogans, advertisements and exhortations, this function has become even more vital. Even good journalism may be an imperfect first draft of history in today's media world, giving a contingent and incomplete picture of unfolding events. But it does create a rough map of present-day reality and, in doing so, helps citizens to find their bearings.
The value of independent journalism is often best seen when it is absent or endangered. When the Russian journalist Anna Politkovskaya was murdered in 2006, the US secretary of state Condoleezza Rice reflected that her death was a reminder that "without investigative journalists who are willing to seek the truth, it's very hard for a democracy to function".
There is already a range of factors - the reliance on professional spokespersons, commercial and political pressures, a culture of trivialisation - that threaten to limit or distort the ability of journalists to serve a democratic society. The underlying defence against those threats is the professional instinct of journalists to find something out and make it public. It is for citizens to decide, in a democracy, what to make of the information that journalists provide for them. They may find the information illuminating or question the motives of those who have put it in the public domain. That very process of decision - the formation of public opinion - is the stuff of everyday democracy.
All of it hinges, however, on the right of journalists to make the information public and protect their sources in so doing. There is no distinction between sources who are known and sources who are anonymous. The decision to destroy documents was strongly influenced by the experience of former Guardianeditor, Peter Preston, in the circumstances in which he found himself. It was neither intended as a challenge to the rule of law nor an affront to democratic order but rather to protect sources and to publish a story of undeniable public importance.