Congressional negotiators are busy working out a compromise with the Bush administration over reforms to the Foreign Intelligence Surveillance Act (FISA). As a result, the specifics of any prospective legislation are currently unknown. But leading civil liberties and national security experts certainly know what they want the bill to contain -- and some, at least, are inclining favorably to a fix that Jay Rockefeller (D-WV), the chairman of the Senate intelligence committee, is proposing. Here's a guide to what to look for.

Carve-Outs vs. Safeguards. What the Bush administration wants -- and probably has done over the past six years -- is to remove FISA protections from a broad swath of people in the U.S. in order to look for terrorism connections. That has had, and will have, broad implications for what the U.S. intelligence community can collect in terms of domestic communications. "Everything that they've proposed to redefine the term 'electronic surveillance' under FISA, the effect is to put millions of communications outside the protection of FISA. It's a carve-out," says Kate Martin, director of the Center for National Security Studies. The person the administration wants to supervise that carve-out for U.S. persons able to be targeted is... the attorney-general.

Rockefeller's proposal, as it stands so far, doesn't change any existing term under FISA. Instead, pursuant to FISA as it stands, the National Security Agency can collect intelligence unimpeded on foreign-to-foreign communications. The administration would be required to go to the FISA Court for a blanket authorization targeting foreign suspected terrorists, in order to make a case that its methods are likely to net foreign communications primarily. All of what follows is a temporary fix -- set to expire after six months so the administration and Congress can work out a permanent solution -- but after 60 days of surveillance, the administration would have to inform Congress and the FISA Court exactly who has had their communications intercepted. And if the administration believes there's a "significant" pattern of communication between someone in the U.S. and a foreign-based surveillance target, it has to acquire a specific warrant from the FISA Court or end the surveillance.

"That preserves the basic framework of FISA," says Martin, "that to listen in to people in the U.S., you need a probable-cause warrant." No carve-out there, but a lot can change in deadline negotiation.

The Definition of "Significant." So far, the bill allows the Justice Department to issue guidelines defining what qualifies as a "significant" amount of communication between someone in the U.S. and a foreign surveillance target. After six months pass, according to Rockefeller's proposal, the administration -- presumably through the Justice Department, but it's not clear -- would submit a detailed report on how the authorization has worked, including on the definition of "significant," for congressional review, in time for the "sunset" provision ending the temporary fix. While any surveillance in the U.S. would still require a FISA warrant, some civil-liberties advocates think the reporting requirement is critical. "Think about the Justice Department inspector general's report into National Security Letters," says Marc Rotenberg, president of the Electronic Privacy Information Center. "What did it find? It found there were abuses of that authority." Look to see how much defense the bill provides against unilateral declarations by the administration that flimsy contact between a foreign target and someone in the U.S. is "significant" enough to merit further investigation.

Can the Government "Sit" on a Wire? "Sitting on a wire" is a shorthand way of referring to the NSA demanding, under FISA authority, all the available communications data from a telecom company relative to a given surveillance target, and then unilaterally determining what it needs. "That would be awful," says Martin. "They would just say, 'We're only taking what we're entitled to take, and Cheney's in charge of sorting it.'" Under FISA, the telephone companies or internet service providers would execute a FISA warrant by providing to the NSA that the warrant says the agency can collect. It's not clear yet whether, in whatever bill emerges, the NSA or the telecommunications companies will have the responsibility for sorting through the material relevant to the warrant.

Will Telecom Companies Have Immunity from Prosecution? According to the Wall Street Journal, the compromise under negotiation ducks the question. If so, it means that, at least so far, the telecoms don't have any legal immunity for improperly turning over more information about subscribers to the government than the government is entitled to. Rotenberg insists on the point. "Private companies have an obligation to protect confidentiality of their customer's information," he says. "We don't want that to sneak into the bill."

Disclosing Past Abuses. This has been a sticking point between Democrats and the administration since Alberto Gonzales proposed amending FISA in the spring. The proposal under consideration doesn't include notification of the extent of the surveillance that has occurred since "Program X" began in October 2001. "It's essential to know what's already happened -- that's neccesary to prevent it from happening again," says Martin. "Congress needs to get this important information, and that needs to be declassified and made public before the sunset on the bill." The current proposal under negotiation doesn't include any reporting requirement for NSA surveillance collection prior to the passage of any FISA fix. Expect the administration to fight such a requirement tooth and claw.

How Temporary Is Temporary? A matter of intermural Democratic dispute. Rockefeller thinks six months is sufficient to assess how the fix in question is working. Sen. Russell Feingold (D-WI), who also sits on the intelligence committee, wants to shorten the provision. If the White House has a position on how long a temporary fix should last, it's unclear.

Ultimately, there's a basic clash of imperatives going on. FISA was written not just as a civil-liberties measure but as a law enforcement one: something that would prevent spying cases from being thrown out of U.S. courts because the basis for the case was an illegal collection of information. The intelligence community isn't concerned about building cases: it's concerned with identifying threats, and that requires lots of data collection. "We've never wrestled with the question of constructing privacy safeguards for U.S. citizens that are subject to massive surveillance by a U.S. surveillance agency," says Rotenberg. "Sen. Frank Church's nightmare was that U.S. intelligence capabilities for surveillance would be turned on the American people. The thin black line on that issue turns out to be the FISA court -- the only form of intervention between power of the intelligence community and American citizens." We're about to learn how durable -- or brittle -- that black line is in the age of terrorism.

Update: This post initially misspelled Marc Rotenberg's name. I regret the error.