Inspector General Glenn Fine said the FBI had no reason to expect that anyone of interest in a terrorism investigation would be present at the 2002 event sponsored by the Thomas Merton Center, a nonviolent anti-war and anti-discrimination group.
The surveillance was "an ill-conceived project on a slow work day," the IG stated in a study of several FBI domestic terrorism probes of people affiliated with organizations such as Greenpeace and the Catholic Worker.
Earlier, in statements to Congress and in a press release, the FBI had described the surveillance as related to a terrorism investigation.
In a letter to the IG, FBI Deputy Director Timothy Murphy said the FBI regrets that inaccurate information was provided to the FBI director and Congress regarding the basis for the agent's presence at the rally.
The IG said a domestic terrorism classification has far-reaching impact because people who are subjects of such investigations are normally placed on watchlists and their travels and interactions with law enforcement may be tracked.
The FBI has broad definitions that enable it to classify matters as domestic terrorism that actually are trespassing or vandalism, the inspector general said.
The Inspector General initiated its investigation of several FBI investigations, following revelations that the Bureau had watched several domestic advocacy groups engaged in non-violent protests that are protected by the First Amendment. It examined several cases between 1999 and 2007.
The report concludes the groups - which ranged from anti-war to animal rights and environmental organizations - were not specifically targeted by the FBI, but that agents used inaccurate or flimsy reasons to open investigations; and, even after no basis to investigate a group was found, the FBI kept its probe open for years afterwards.
In one instance, several activists from Greenpeace were placed on a terror watch list while their travel and protest activities were maintained in FBI files.
Among the cases examined by the IG:
The Thomas Merton Center in Pittsburgh: Members of an anti-war organization holding a rally against the Iraq War in November 2002 when, the IG report says, a rookie FBI agent went to investigate and photographed a woman "who appeared to be Middle Eastern."
In 2006, when controversy first erupted over whether the FBI had spied on protesters because of their anti-war views, the agency issued a news release saying the surveillance had been based on an ongoing investigation.
FBI Director Robert Mueller told a Senate hearing that the bureau had been trying to identify a particular individual believed to be in attendance.
The FBI's statements to Congress and the public were not true, said the IG, who found no evidence that the FBI had any information at the time of the event that any terrorism subject would be present.
According to the IG, the Office of the Chief Division Counsel in the FBI Pittsburgh Field Division created a document that said the surveillance was supposedly directed at an individual living in Pittsburgh who was of interest to the FBI based on evidence developed in a terrorism probe.
"We determined this version of events was not true," said the IG.
The inaccurate statements may have been inadvertent, but the IG said it is more likely that the document reflected an effort to state a stronger justification for the surveillance.
In its investigation, the IG writes that the FBI's excuse for monitoring the Merton Center rally was that it was a slow day after Thanksgiving and that the agent needed some "make-work," and so was asked to attend the rally to identify terrorism suspects. The agent said that he believed he needed to show his supervisor that he was "earning his pay."
PETA: The FBI office in Norfolk, Va., opened a terror investigation of the animal rights organization in May 2001, and kept the probe open for six years, even though there was no evidence of illegal activities to justify it; nor were there credible links found between PETA and other animals right groups that engaged in criminal activity (such as the Animal Liberation Front, which had been designated a domestic terrorist group).
The IG felt that the investigation into any possible ties between PETA members and the ALF should have been conducted as a preliminary inquiry rather than a full investigation, and stated that the probe's six-year length was "unreasonable and inconsistent with FBI policy."
Greenpeace: The FBI opened a series of investigations into the environmental group between 1992 and 2002, initially limited to Greenpeace members' plans to disrupt BP/Amoco energy projects in Alaska. (Several Greenpeace members were arrested in 2000 for trespassing while attempting to chain themselves to equipment at a pipeline project site, halt construction, and hang banners.)
These investigations were later broadened to include perceived threats against Strategic Missile Defense Initiative activities in Alaska and elsewhere.
The IG states that Greenpeace's tactics "could be considered forms of civil disobedience and would not normally be considered acts of terrorism," but adds that the FBI developed some credible information that individuals being investigated would promote goals that might include acts of violence, such as blowing up a pipeline.
In 2004 the FBI Dallas office opened an investigation of two Greenpeace members under the Acts of Terrorism classification, due to an alleged conspiracy with respect to protests against ExxonMobil and Kimberly-Clark. No evidence of any actions against either corporation (such as disruptions at shareholder meetings) was found, yet the investigation remained open for three years, and the expanded list of individuals being examined was placed in the Violent Gang and Terrorist Offender File (VGTOF) database.
When queried, the case agent said that, just because no criminal action had been taken at one shareholders meetings did not mean that criminal actions weren't being planned for the next.
The Catholic Worker: Beginning in 2003 domestic terrorism investigations were opened against members of the religious group following vandalism and trespass incidents at military recruiting offices in Milwaukee; Ithaca, N.Y.; Norfolk, Va.; and Offutt Air Force Base.
FBI agents also monitored rallies, or in advance of FBI-designated "special events" where protests or acts of civil disobedience might be expected; and recorded and retained data about Catholic Worker members obtained from other agencies.
The FBI classified "peaceful trespass on a military facility" and acts of vandalism, including the spilling of purported human blood, as potential acts of terrorism. The IG agreed that acts which went beyond simple trespass to destruction of government property could be classified acts of terrorism.
Seattle activist Glen Milner: A member of the anti-war group Ground Zero Center for Nonviolent Action, Milner was "under watch" for planning "some sort of demonstration" to mark the arrival of Navy ships at the 2003 Seafair Festival.
The IG noted that, according to the FBI's file, prior to the demonstration a Coast Guard Special Investigative Agent contacted Milner and, under the pretense of being a Ground Zero sympathizer, obtained information about the planned demonstration - a flotilla of boats flying anti-war flags, dubbed the "Peace Navy."
The IG found that the FBI acted properly, and there was no evidence of criminal activity. The FBI closed its investigation 2 days after Seafair ended.
CBS News' Stephanie Lambidakis and David Morgan contributed to this report.