"The extinction of privacy is a real possibility," said Barry Steinhardt, director of the ACLU's Technology and Liberty Project. "We believe that privacy is not yet dead — it is a patient on life support."

The online clock is patterned after the "Doomsday Clock," created by the Bulletin of the Atomic Scientists in 1947 to warn against a nuclear holocaust. Midnight symbolized a total "1984"-style "surveillance society."

"Every generation deserves its own clock," Mr. Steinhardt said in a teleconference yesterday announcing the project and a new report on mass surveillance by the government.

He said that an explosive increase in new technology and data mining is fueling the trend and creating a false sense of security — from satellites to national-identity systems, the National Security Agency's warrantless surveillance program, DNA data-banking and Web search engines that store every query, even satellites.

"The false security of a surveillance society threatens to turn our country into a place where individuals are constantly susceptible to being trapped by data errors or misinterpretations, illegal use of information by rogue government workers, abuses by political leaders — or perhaps most insidiously, expanded legal uses of information for all kinds of new purposes," the report says.

"We are far too close to the midnight of a genuine surveillance society, and the second hand has not stopped sweeping around the dial," the report says.

The "surveillance" clock, a digital display viewable from the ACLU's Web site, is now set at six minutes before midnight. The ACLU says it will be updated as events warrant moving the time closer or further away from a "surveillance society."

"This might have seemed like a crazy idea 20 years ago, but it is no longer a crazy idea and this is the direction in which we are moving," Mr. Steinhardt said. "September 11 has only accelerated the trend."

The report is an update from the organization's January 2003 report titled "Bigger Monster, Weaker Chains: The Growth of an American Surveillance Society" by Mr. Steinhardt and Jay Stanley.

The number of policy milestones enacted by the government in the current decade rivals that of the entire past century, the report finds. Since 2000, the USA Patriot Act, Real ID, the proliferation of identity checks, health privacy legislation and the NSA "terrorist surveillance program" have been approved by Congress.

The ACLU cites ten major policies regarding privacy in the 20th century, including the founding of the NSA, application of Social Security numbers and the FBI's creation of an electronic fingerprint database.

"With a flood of new technologies that expand the potential for centralized monitoring, a president who believes he can unilaterally sweep aside the laws that restrain government spying, a docile congress and courts, as well as a cadre of mega-corporations that are willing to become extensions of the surveillance state, we confront the possibility of a dark future where our every move, our every transaction, our every communication is recorded, compiled and stored away, ready for access by the authorities whenever they want," the report says.