How to Spot a Terrorist

A young man walks into a Home Depot and buys a large quantity of acetone. Later, a young man walks into a beauty supply store and buys hydrogen peroxide. Still later, a young man is observed parked outside a nondescript federal building in a rented van, taking photographs.

No crime has been committed. But should any of these activities (acetone and hydrogen peroxide can be components for explosives) be reported to and evaluated by law enforcement officials? If they are reported, the government may infringe on privacy and civil liberties. If they are not, we might not know until it’s too late whether it was the same young man in each instance. We might miss the next Timothy McVeigh.

This dilemma was at the heart of hearings before the Senate Homeland Security Committee last week, in which several federal officials warned that “homegrown terrorists” represent the nation’s greatest emerging threat. According to the F.B.I. director, Robert Mueller, Al Qaeda “has looked to recruit Americans or Westerners who are able to remain undetected by heightened security measures.” This reality has led Janet Napolitano, the secretary of Homeland Security, to conclude that “homeland security begins with hometown security.” And hometown security begins with locally based observations of “suspicious” activity. So, can we encourage such observation without also encouraging a disregard for privacy and constitutional rights?

We may get our answer from a project now being undertaken by the Justice Department called the Nationwide Suspicious Activity Reporting Initiative. Federal, state and local law enforcement officials have set up “fusion centers” for the program in about a dozen cities, including Boston, Chicago and Houston, where reports of suspicious activities made by citizens and the local police are collected and analyzed for disturbing patterns.

Suspicious Activity Reporting begins at the troubling intersection where law enforcement meets intelligence. Its premise is that if potential attacks are to be prevented, and not merely responded to, law enforcement must focus on precursor conduct — surveillance or “casing” of bridges or train stations, for instance — that may not itself be criminal, but may signal a coming attack.

One need only look to the events of the past year — the shootings at Fort Hood, Tex.; the attempted bombing of a jetliner on Christmas Day; the Times Square bombing attempt; the New York subway plot — to see the point. Each of these attacks and attempted attacks was preceded by “precursor conduct,” legally protected actions like chatting on the Internet or purchasing legal chemicals or applying for a visa, that combined with other information might have tipped off law enforcement agents to the intended act of terrorism.

The Suspicious Activity Reporting program recognizes both the necessity for a focus on precursor conduct and the potential for abuse. It strikes a balance by establishing a uniform process for gathering and sharing information. It seeks to avoid racial profiling and other law enforcement excesses by requiring that the reports be based on the evidence of suspicious conduct, not on what the person looks like or where he comes from.

The government consulted with civil liberties groups as it devised the initiative, and they secured changes in the program to assure that the threshold for criminal conduct would not be lowered and that individual privacy would not be violated by the willy-nilly entry of innuendo into a government record. As Michael German, the security policy counsel of the American Civil Liberties Union and a former F.B.I. special agent, put it last year, “The revised guidelines for suspicious activity reporting establish that a reasonable connection to terrorism or other criminal activity is required before law enforcement may collect Americans’ personal information and share it.”

Nonetheless, the A.C.L.U. is now taking issue with the program, saying that it “increases the probability that innocent people will be stopped by police and have their personal information collected.” Mr. German worries that an effort like this “moves the police officer away from his core function, to enforce the law, into being an intelligence officer gathering information about people.”

At bottom, whether the civil liberties risks posed by the reporting program are justified turns on whether the administration’s claims about the evolving threat are true. The attacks of the last year suggest that they are. As for the idea that it will bring police departments into new territory, surely police officers have always been on the lookout for precursor conduct — burglars casing a home or bank, for instance. The difference here is one of degree.

Paradoxically, perhaps the biggest hurdle the initiative faces is not civil liberties worries but the age-old barrier between federal law enforcement and its state and local counterparts. The F.B.I. has raised concerns about sharing intelligence with state law enforcement because some states’ open public records laws might result in the bureau having to make public some of its data. And, in a time of shrinking budgets, turf battles between the fusion centers and federal law enforcement are a certainty.

Civil liberties and bureaucratic concerns are legitimate. But this initiative represents the administration’s first thoughtful steps in fulfilling President Obama’s commitment to defining a lasting rule of law for this brave new world. We must make it work.

John Farmer Jr., a former senior counsel for the 9/11 commission, the dean of the Rutgers School of Law-Newark and the author of The Ground Truth.