The intelligence reports reviewed by the subcommittee were produced by officials in the Homeland Security Department's Intelligence and Analysis division, which was created after the Sept. 11 attacks with the hope of connecting the dots to prevent the next terrorist strike. This division has never lived up to what Congress initially hoped for.
Lieberman and Collins were the driving forces behind the creation of the department. Fusion centers, the analytical centers intended to spot terrorism trends in every state, are held up by many as the crown jewel of the department's security efforts.
"I strongly disagree with the report's core assertion that fusion centers have been unable to meaningfully contribute to federal counterterrorism efforts," Lieberman said in a statement Wednesday, singling out six "shortcomings" in the report. Collins issued a separate statement that listed four shortcomings.
A Lieberman spokeswoman said the report came from the Permanent Subcommittee on Investigations, rather than the full committee.
"I know that seems odd, but this is strictly a PSI report," Lieberman spokeswoman Leslie Phillips wrote in an email.
The Homeland Security Department and several major law enforcement associations also strongly disagreed with the findings. Pulling back federal money for the program would force state and local governments to cover all of the costs.
The department said the report is outdated and inaccurate. It cited specific examples of how the centers have contributed to counterterrorism efforts in major cases, including the 2010 attempted car bombing in New York City's Times Square. That's an example the subcommittee challenges in its report.
The subcommittee reviewed more than 600 unclassified reports over a one-year period and concluded that most had nothing to do with terrorism. The subcommittee chairman is Democrat Carl Levin of Michigan, and the top Republican is Sen. Tom Coburn of Oklahoma.
One center cited in the investigation wrote a report about a Muslim community group's list of book recommendations. Others discussed American citizens speaking at mosques or talking to Muslim groups about parenting.
No evidence of criminal activity was contained in those reports. The government did not circulate them, but it kept them on government computers. The federal government is prohibited from storing information about First Amendment-protected activities not related to crimes.
States have had criminal analysis centers for years, but the fusion centers were set up after the 2001 attacks as officials realized that a terrorism tip was as likely to come from a local police officer as the CIA.
Though fusion centers receive money from the federal government, they are operated independently. A federal law co-sponsored by Lieberman and Collins authorized that centers cover criminal or terrorist activity.
Five years later, Senate investigators found, terrorism is often a secondary focus.
The report is as much an indictment of Congress as it is the Homeland Security Department.
"Congress and two administrations have urged DHS to continue or even expand its support of fusion centers, without providing sufficient oversight to ensure the intelligence from fusion centers is commensurate with the level of federal investment," the report said.
One of the report's recommendations is that the department needs to do a better job of tracking how its money is spent; that's a recommendation with which both Collins and Lieberman agree.
Despite that, Congress is unlikely to pull the plug because the program means politically important money for state and local governments, and Homeland Security officials are adamant that the money is well spent.
In 2010, after Faisal Shahzad was caught for trying to blow up a vehicle in New York's Times Square, fusion centers examined their own systems to see if there were any relationships with intelligence they had related to Shahzad, said John Cohen, a senior advisor to the Homeland Security secretary.
Cohen said centers in Florida and Virginia discovered individuals who had connections to Shahzad but who were unknown to the FBI. The centers shared the information with FBI investigators, Cohen said, and that produced additional leads that are still under investigation.
But the example is one the congressional investigators condemn. "The information does not appear to have played any key role in the Shahzad case," the report said.
Cohen also cited a 2011 case in Seattle in which two men approached someone in Seattle about purchasing weapons. The person they approached happened to be a police informant and reported the incident to his handler, Cohen said. The police handler was assigned to the local fusion center that was able to identify the two people who approached the informant, he said.
The fusion center did more analysis on the men, including digging into their criminal backgrounds, determined they might want to do more than just purchase firearms and handed the information over to the local FBI-led joint terrorism task force. The men were arrested and charged with plotting a terror attack on a military office in Seattle. While the subcommittee did not review this particular case, court records state that the men approached the police informant and were specific about their plans to attack a military office when they asked about obtaining weapons.
The recent Senate report is not the first time questions have been raised about civil liberties and privacy protections in fusion centers.
The centers have made headlines for circulating information about supporters of GOP presidential primary candidate Ron Paul, the ACLU, activists on both sides of the abortion debate, war protesters and advocates of gun rights.
The Obama administration has put policies in place and required that fusion centers have privacy and civil liberty policies in order to receive federal funding. But the ACLU and other civil liberties organizations continue to call for better privacy protections.