Today, in a truly stunning conclusion to a long series of lawsuits, the Obama administration announced that it will begin to regularly release the vast majority of Secret Service records tracking visits to the White House.

Score a big victory for Citizens for Responsibility and Ethics in Washington (CREW), which tirelessly litigated for broad access to the records via the Freedom of Information Act.

In response to the White House’s pledge to routinely release electronic visitor records once they are three to four months old, CREW has decided to drop its outstanding cases pursuing information related to the visits of evangelical leaders under the Bush administration, as well as visits by coal and health care executives.

The agreement leaves the question of the visitor records’ status under the Freedom of Information Act somewhat unsettled. While three district court rulings have found that the records are accessible under FOIA, no higher court has decided the question.

The White House stresses that the new release program is voluntary, meaning that no court forced the action. Any president—including this one—could suspend or modify it at any time, at the risk of public outcry.

And until the first release—slated for late December 2009—we won’t know how forthcoming the White House plans to be.

Indeed, there are three categories of visits that will continue to be withheld under the policy: Information that could threaten national security, records describing the visits of personal guests of the Obama and Biden families, and records related to a small group of “particularly sensitive meetings.”

There’s obvious room for leeway in those categories. Will, say, all ambassadorial visits be exempt, on supposed national security grounds? While the administration says that only personal events, or “visits that do not involve any official or political business” will go undisclosed, in clubby Washington, what’s business and what’s pleasure? (Remember the phrase “Friend of Bill”?)

While the administration has promised to disclose each month how many times it’s using the “sensitive meetings” exemption, which should help curb abuse of that particular category, there’s no promise to publicly track the number of visits withheld under the personal or national security categories.

On that sensitive meetings category, the White House promises only to stand in the way of a small group of records—the example is given of records describing the visits of potential Supreme Court nominees—and to release those records once they are “no longer sensitive.” It’s hard to know what either phrase would mean in practice.

Let’s take the White House’s Supreme Court example. For the sake of argument, grant that Sonia Sotomayor’s pre-nomination visits to the White House were particularly sensitive—though I can’t see why they are more sensitive than a president’s meetings with any other potential major appointee.

When would it no longer be “sensitive” to admit that Sonia Sotomayor visited with Obama? Presumably, once her name was announced. But if Obama met with other potential nominees who never got the nod, when is it no longer “sensitive” to release their visit records? Once they were crossed off the short list? Once Sotomayor was announced? Once she was confirmed? Once they retire from public life? Once they are dead?

The Obama administration has done something laudable, and this is a landmark day for the public’s right to know who is coming to the White House and meeting and influencing the president and his staff.

But as long as the disclosures are done at the president’s discretion, and not with the force of law, the public may never know what they are missing.

Clint Hendler is the managing editor of Mother Jones, and a former deputy editor of CJR.