On December 10, 2009, the Senate Judiciary Committee voted to send the Free Flow of Information Act for consideration before the full Senate.

For the journalism advocacy groups pressing for a federal shield law to give reporters greater protection from being forced to identify their confidential sources—or divulge information from them—in federal trials, it was a heady day. The House had already passed a version of the bill. The Obama administration had signaled its support. No previous attempt at crafting a federal shield had come so far, and never had victory seemed so close.

But as Congress heads home for its August recess, the clock is ticking. The administration’s major legislative efforts, met by staunch delaying and oppositional tactics from the Republicans, have used up much of the legislative calendar. And recent events have added a wrinkle.

“The WikiLeaks matter didn’t help us any,” says Kurt Wimmer, a media lawyer at Covington & Burling, and a main negotiator for media organizations supporting the bill.

Last week, Senator Charles Schumer of New York, one of the bill’s primary sponsors, put out a statement promising to amend the legislation before any floor vote to explicitly exempt sites like WikiLeaks from the shield’s protection.

Schumer’s statement emphasized that he thought the bill as written would not offer the people behind WikiLeaks any protection for two reasons: they wouldn’t meet the bill’s definition of a journalist, and the bill’s provisions weakening its protections in cases of national security would prevent WikiLeaks from gaining much protection in cases like the Afghanistan leaks.

But even though Schumer claimed that these provisions already “ensured that Wikileaks could never assert the privilege,” the statement added that he would work to insert language to exclude organizations “whose sole or primary purpose is to publish unauthorized disclosures of documents.”

Schumer’s statement, and the question of whether or not the bill would cover an outlet like WikiLeaks, provides a roadmap to the bill’s two main sections: one defines who is entitled to the protection, and the other describes how judges should go about applying the law’s protections on a case by case basis.

The definition of a journalist has been one of the drafting process’s stickiest questions, with many journalists favoring a function-based definition, one that judges a person seeking the shield’s protections by what they do (whether or not they act as a journalist) rather than a status-based definition, which would include some test of who the journalist is—simply put, whether or not they are a professional, however defined. Paul Boyle, the Newspaper Association of America’s chief lobbyist, says that further changes are likely to this portion of the bill, requiring that the claimant show that they regularly did journalism before they appeared in court seeking to foil a subpoena with the shield.

“There’s going to be a provision indicating a track record of journalism,” says Boyle, emphasizing that it wouldn’t be a professional standard. “It’s more about having a record of putting yourself out there as a journalist.”

This change may have been foreshadowed when Schumer promised to make further revisions to the bill’s definition of a journalist, in cooperation with Senator Dianne Feinstein of California, who chairs the Senate’s Intelligence Committee, and who voted for the bill in the Judiciary Committee only after expressing serious reservations. It’s also worth noting that there will inevitably be some differences requiring reconciliation between the version of the bill already passed by the House and whatever emerges from the Senate, a fact which further conceals any final law’s contours.

The bill’s other main portion lays out the limited circumstances under which the new law would allow a federal judge to decided that a subpoena request against a covered journalist would be allowed to proceed. In criminal prosecutions, a judge would have to determine that information held by the journalist would be essential to resolving the case, that there was no other potential source of the information, and that the journalist had been unable to offer adequate evidence that requiring testimony would be against the public interest.

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