The attacks of September 11, 2001, ushered in a multitude of legal transformations that restrict civil liberties in the name of national security. But discussion of one change that could have particularly devastating consequences has been strangely limited. It concerns the secret and mysterious Foreign Intelligence Surveillance Court (FISC), which exists in a legal twilight zone with virtually no connection to the Constitution or Bill of Rights.

Since its creation twenty-five years ago, the FISC has steadily amassed more power to intrude on people’s lives than any court in our history, and it has never denied a government application for a wiretap or search in more than 14,000 requests. Last year, the seven judges on the court granted almost as many warrants as the 600 or so trial judges in the entire federal judiciary.

The FISC is certainly a peculiar institution. It hears only one side of every case–the government’s. No defense attorney or member of the public has ever attended one of its sessions. Its judges (expanded to eleven under the Patriot Act), who are current federal trial and appellate judges, are handpicked by Chief Justice William Rehnquist for rotating terms. A FISC appointment is prestigious; jockeying for one is described as intense. FISC decisions cannot be appealed by a defendant–not even to the Supreme Court.

How did such a court come to exist? The original idea was seen as a good-government reform. Before the FISC, which was created with bipartisan backing under the Carter Administration, the President could order a wiretap or break-in without a warrant if he unilaterally determined it was necessary for national security reasons. Because the legal authority to do so was always suspect (and because President Nixon abused this privilege by allowing the FBI to monitor thousands of Americans, including members of the White House staff), the FISC was created to check executive power by imposing standards and judicial review on this process.

From its inception, getting a warrant from the FISC was far easier than from a regular court. Probable cause was needed, but rather than requiring suspected criminal activity (as in regular courts), such a warrant needed only to allege that the target was a “foreign power” or “agent” of one. This exception to the probable-cause requirement of the Fourth Amendment was considered acceptable because warrants were supposed to be limited to the gathering of foreign intelligence information, not for prosecution in a regular criminal court. Most intended targets were foreign embassies and their personnel. Only Americans believed to be engaged in espionage or in contact (even if innocuous) with an intelligence target could be monitored without Fourth Amendment protections.

This changed dramatically in the mid-1990s. Congress expanded the FISC to authorize not only electronic surveillance but also physical searches of people’s homes. Armed with an FISC warrant, FBI agents could now break into private homes and never tell the occupants they had been there, thus foreclosing any possible court challenge to the warrant (you can’t challenge an illegal break-in if you don’t know it happened). Evidence gathered with FISC warrants also was increasingly used to prosecute people in criminal court on charges that had little or nothing to do with national security; at least a few dozen such cases have come through the courts in recent years.

Then came Attorney General John Ashcroft, who a few months after September 11 decided to apply the FISC to domestic criminal investigations. Now, if a run-of-the-mill domestic criminal prosecution has even the remotest “foreign” association, the Justice Department can do an end-run around the Fourth Amendment and gather evidence under the FISC. Examples of cases that might qualify: an American citizen of Arab descent suspected of any illegality, from drug-dealing to cigarette-smuggling; a political supporter of organizations like the Palestinian Authority, Sinn Fein or Greenpeace; a donor to charities that are suspect, as defined by the Justice Department.

Unsurprisingly, in a case of the fox guarding the henhouse, the FISC itself approved expansion of its powers last November. Its three-judge appeals panel, whose ideological leader, Laurence Silberman, is arguably the most hard-right activist in the federal judiciary, tore down the already weakened “wall” that had blocked intelligence agents, unbound by Fourth Amendment constraints, from sharing information with prosecutors, who are required to abide by the Fourth Amendment. The decision cannot be appealed (the ACLU filed an unprecedented motion seeking Supreme Court review, which was denied).

The FISC’s newfound power may well enable the FBI–the agency that seeks the most FISC warrants–to extend the scope of its dubious practices of spying on political activists. As David Cole and James Dempsey document in their book Terrorism and the Constitution, the FBI has often interpreted “support for terrorism” to include peaceful humanitarian and political activities.

Congressional oversight, other than some recent low-intensity efforts by Senators Patrick Leahy and Arlen Specter to shed more light on the court’s doings, has been almost nonexistent. Public disclosure to Congress is limited to an annual one-paragraph letter specifying the number of approved FISC warrants. In 2002 that number was 1,228–roughly more than double a decade ago. Given the number of warrants approved since its inception, it is likely that tens of thousands of people have been spied on or had their homes broken into without their knowledge. Also, there is discussion in the intelligence community of creating branches of the FISC in several major cities.

The Fourth Amendment is the heart and soul of a free society–“the right to be let alone,” in the words of Supreme Court Justice Louis Brandeis. FISC operates in a parallel universe where the Fourth Amendment is essentially defunct and the right to be left alone is meaningless for those Americans targeted. Cleverly, the FISC statute uses legal nomenclature (“probable cause”) and real federal judges to convey the look and feel of constitutional legitimacy. In fact, a defendant might have a better chance of being acquitted in China than in a US court using FISC evidence. The precise role of the FISC in the new antiterror legal paradigm remains to be seen–or not seen, as the case may be–but there’s little question the power is there for the taking, should the Attorney General avail himself of it. Perhaps Ashcroft has done so; under the rules, we cannot know.