Geoffrey Stone eloquently reminds us of the ways in which secrecy can be used to avoid democratic accountability. The greatest prophet of transparency, of course, was Louis Brandeis. "Publicity is justly commended as a remedy for social and industrial diseases," he warned in Other People's Money (1914). "Sunlight is said to be the best of disinfectants; electric light the most efficient policeman."

But in addition to reminding us of the virtues of transparency, Brandeis was also the greatest 20th century advocate of the necessity of privacy. Might there be a tension between the two values? Stone acknowledges, "Some measure of secrecy is, of course, essential to the effective functioning of government, especially in wartime." But who should decide how to strike the balance between privacy and transparency? Obama at the moment has unequivocally embraced transparency, promising that his new Chief Technology Officer will ensure that administration holds open meetings with live webcasts, and uses blogging software and wikis to communicate with the public. This is a welcome contrast to the self-defeating and instinctive secrecy of the Bush administration. But as the Supreme Court has recognized, some degree of privacy is necessary for free and open deliberation by government officials - for testing unpopular ideas and refining complicated policies before they're submitted for public debate. In some of the great legislative debates on the horizon - over health care, for example, or economic reform - the White House will be assailed for not disclosing enough of its internal deliberations. Some of this criticism will be politically motivated: many of the same Republicans who defended secrecy and executive power during the Bush years will rediscover the virtues of transparency and limitations on executive power that they demanded during the Clinton years. But more broadly, there will genuine tensions between the need for deliberative privacy and the pressures for transparency, and striking the balance may pose some of the hardest choices of the new administration.

In other cases, the critics of transparency will not be administration officials but self-interested citizen. Stone endorses, for example, a federal Free Flow of Information Act that would allow journalists to protect their sources. But the greatest obstacles to the passage of this law, at the moment, are bloggers who oppose the fact that the law would limit the source privilege to professional journalists. (Without the limitation, any citizen with WiFi could claim to be a journalist and avoid testifying in court.) The fact that the federal shield law may fail despite bipartisan support reminds us that many self-styled watchdogs abandon their support for transparency when they feel that their own interests are threatened.

None of this diminishes Stone's prescient reminders about the virtues of transparency. But it suggests that striking a balance between deliberative privacy and transparency will be one of the many difficult challenges for President Obama to resolve.